93 new of 184 responses total.
Re #90: Brakes use ethylene glycol rather than petroleum-based hydraulic fluids. (The reason is that glycol absorbs water, preventing it from freezing or corroding the brake parts. This isn't necessary for power steering and transmission systems which are kept dry by the heat of their operation.) Glycol is biodegradable, so you wouldn't notice an ecological problem even if fair amounts of it leaked.
Glycol is also less destructive of the hoses necessary for brake lines. However glycol is very bad if heated to high temperatures, and it is an inferior lubricant. It should also be added that glycol is quite toxic, although initially inebriating. The green fluorescent dye (uricine) is added to it to suggest that it isn't healthy.
Re #91: Most probably do, but you're *supposed* to change it every so often.
Okey dokey... so I have this 99 Alero that's not been giving me any trouble at'all, til today. It's got power steering and on the way in to work this morning (luckily I was almost all the way there) it got a bit harder to steer, then in pulling into the office parking lot it was almost impossible to turn the wheel. Haven't really had a chance to look yet, or call a mechanic, but does this sound like, to anyone, it just needs more power steering fluid?
It sounds to me like you need an older car. Jim has a 1968 Volvo without power steering that you can have if you come get it. It will start if you push it downhill.
Actually, Anne, it could be either. First thing I'd check is to see
if the (I'm presuming it has one, most cars these days do) serpentine belt
is broken.
re #96- great... now I have to find a hill. Or can I pick up one of those too? re#97- Thanks John. It's me lunch time now, so I have time to go check. Will report my findings shortly. (an hour or so...) (and I even know what a serpentine belt is! My last Olds had one that had to be replaced, though it didn't break just was about to.)
Look for a fluid leak under the front, too. If the battery light came on then I'd buy the belt theory, but otherwise you may have a leak. Ha! Possible vindication for my leaky-future-hydraulics theory! ;)
Glad to be of service, Scott. ;) And no, the battery light didn't come on. Didn't see any leaks (then again I parked next to a melting snow pile...) but the serpentine belt was fine, and the power steering fluid is empty. Not sure how this happened, but for now my wonderful roommate is going to pick up some fluid for me and as soon as I can I will take the car in to get looked at.
Sorry, Jim got rid of his three old Jeeps and would never own a Volvo as they are very fuel inefficient and won't carry refrigerators easily.
<grumps> Wasn't the power steering fluid. Car no drive, I'm at work still waiting to be picked up by my wonderful, helpful roommate. <sighs and wanders upstairs to wait>
Sounds to me like there was probably a reason there wasn't any power steering fluid in the reservoir. Must be a leak somewhere...
Maybe some catastrophic leak out in the street, so there wasn't much left to make a visible puddle in the parking lot? :(
I'm reminded of the time the main seal on my Crown Victoria's transmission blew out on the freeway. All the transmission fluid wound up on US-27 somewhere. By the time I realized something was amiss, it was already far too late. (Why is there no 'transmission fluid pressure' warning light?)
I figure the first leak was something that happened on the road so it wasn't immediately noticeable. Before my last post I added power steering fluid and when that didn't help I just parked the car and went to call my roomie and a couple car places. Later, I actually checked the fluid level and it was empty again, this time I saw a puddle under my car and could see little drips from testing it in the parking lot and re-parking. Nice thing is (I think...) when I bought it I was talked into an extended warranty- so it's at a dealership now and shouldn't (hopefully) cost me anything to fix. If it does cost me, I may have to yell at some people.
re 96: rotfl. :)
;-)
Re #101: So I'm guessing you and jim know nothing of Volvos built after 1970? If you did you'd know you can damn near fit two refrigerators in the wagons. There's even a local harpist who uses one for local gigs. Oh yeah, you're also wrong about the mileage, unless your talking turbos.
Re #109 -- you'll have to complain to Mr. Joseph M. Saul about that, not Sindi & Jim.
Wrong. Go back and look.
Do they get 40 mpg and let you open the hatchback to carry tall things?
!sed -n 1205,1206p /bbs/cars/_121 Looks pretty clear to me.
(That's resp 96 - #109 referred to #101.)
Oh bother... the problem turned out to be the 'power steering fluid return line' okie fine. Next problem- AFTER they completed the work they contacted the warranty people for payment- only to find that my 'bumper to bumper' doesn't happen to carry hoses. The return line is a metal pipe- they don't care, still won't cover it. Heh, according to a co-worker- bumper to bumper means either bumper, but nothing between them. I have to go yell at more people over the phone.
Hey, it's better than when the dealership that'd sold me my Dodge
refused to pay for the work that was necessitated by something that they
screwed up. That left me out $1200.
Yah well, this is only $222, but it's still real annoying.
I take it hoses are considered a 'regular maintenance item' and that's why they're excluded?
Something like that, yeah.
$222 is $222. No getting around it.
I took the Grand Am to a radiator guy nearby who pronounced the problem
to be a cracked cylinderhead. There was an extension of coverage by GM to
7 years or 100,000 miles to cover this, as a lot of these cars were having
this problem. The car has 96000 miles, but is a '93 and well outside the
time limit.
The guy who looked at it says he can fix it for $1300 including a new
water pump, oil, coolant, and timing belt (??? I was pretty sure that the
diagrams for that engine in the Chilton manual showed chain timing. That's
the first thing I looked for when I got the car.)
A second place I called quotes anywhere from $900 to $1300 depending on
whether it *is* a cracked head or just a blown gasket. (He thinks it might
just be the gasket.) But his price doesn't include a water pump.
As the car has 96K on it, there doesn't seem to be enough probable
life in it to justify the cost. A few things are new on it, and I'd be
getting a couple other things new with the repair. But a few other things
I don't trust.
Exploring one of my other options, I'm asking if anyone has knowledge
of Ford diesel-powered Escorts from the late '80s. Someone I know (and a
few other people on Grex also know him) will happen to have one for sale
for a rather cheap price (he *paid* a rather cheap price for it). It most
likely has a God-awful number of miles on it, but this may be mitigated
by the reputation of diesel engines for robustness, simplicity, et al.
And the cheaper a car is, the less distance it has to travel to "pay for
itself".
Anyone know if these cars are any good, or if there are problems with
them, particularly after that much time, and|or why Ford stopped making
them? Or did they?
The first generation of american diesels ended up with a bad reputation. The GM V8 diesel of ca. 1980 was basically a gasoline V8 turned into a diesel, and it turned out to be under-engineered for what it was supposed to do. A properly designed diesel engine really has to be designed from the ground up to be more robust, because due to the higher compression ratio it's under quite a bit more stress. Diesel engines also have a narrower power band; which means they really need more speeds than the equivalent gasoline car. That's one of the reasons trucks typically have 18 speeds or more. That's overkill for a car, but a 6 speed gearbox would not be out of line. The reasons diesels have gone out of favour in cars is more than that. Firstly, diesel fuel used to be much cheaper than gasoline. That changed a few years after diesel cars came out. Secondly, diesel fuel is more dirty when it burns than gasoline. This produces problems with pollution requirements, and is also an aesthetic issue as drivers contend with nasty black sooty deposits on their cars. I think these are the main reasons why diesels went out of favour. Diesels traditionally are harder to start in cold weather than gasoline -- supposedly the newer automotive units have fixed this, but I wonder how well they age. Diesel fuel is also harder to get -- it's easy to get along expressways, but it's not necessarily at the corner gas pump in town.
Hard winter starting on modern diesels is mostly a matter of glow plug maintenance. If you have a bad plug, you'll never get that cylinder to fire on a cold day. Leaky injectors will burn out glow plugs in no time -- the constant drip of fuel kills them off somehow. Diesel cars are popular in Europe, where fuel is expensive. They aren't so popular here. Partly this is because Americans are fixated on cars that are powerful and quiet, and diesels aren't really either. I have no idea what the diesel Escort's reputation is; I didn't even know they made one. In general I'd be suspicious of a small diesel made by a U.S. car company because I don't feel they have the experience to really do it well. Volkswagen has made some really excellent small diesels, though.
Also, if you run a diesel out of fuel, it is a major deal to get it going again. You can't just pour in more fuel like you can with a gas engine. At least, that's the way it used to be...
Re #123: Ford did not build the engine for the Escort diesel. I believe it was Japanese. Re #122: The Buick diesel was a prechamber design, not direct injection; this speeds ignition and combustion at the cost of greater heat loss. This qualified it as a high-speed diesel. Such engines do not need the huge number of speeds required of semi tractors and their medium-speed, direct-injected engines. (Typical power band on a semi is 1600 to 2500 RPM; that goes all the way from maximum torque to redline. When your usable range is about 1.5:1, you're going to need lots of gears to keep the engine running there over road speed.) One of the biggest problems with the Buick diesel was lack of fuel conditioning. A little bit of water or paraffin in the fuel, and the engine would quit when the temperature dropped. The engine was introduced on the verge of a winter when fuel supplies were running short and refiners and distributors were pumping the sludge out of the bottom of their tanks; without water traps and fuel heaters, the Buick was doomed. Modern common-rail diesel fuel systems have beaten the diesel clatter problem as well as the smoke. I've driven a turbodiesel Focus; it's a lively, torquey little beast, and quiet too.
Re #124: That isn't quite the big deal it used to be. Even on my friend's 1980 VW Dasher Diesel it wasn't a catastrophe, it just took a lot of cranking. The only fuel pump was a vane pump in the injector pump, and you had to crank until it pulled fuel all the way from the tank. That car had acceptable performance with just a four-speed, incidentally. It wasn't exactly peppy, but it did okay. This was before VW started turbocharging their diesels; the turbo makes a huge difference in power. Without the turbo the little diesel (I think it was 1.6L) only cranked out 49 horsepower. Re #125: The newest VW turbodiesels are surprisingly quiet, too. There's a bit of clatter, more than a gas engine, but it's not objectionable. The most obvious sign a new Jetta TDI is a diesel, other than the exhaust odor, is the turbo whine.
resp:122 (First sentence) No, not according to a mechanic friend of mine.. and he drives a particular car that proves it. Your next sentence seems about right-- GM shot themselves in the foot by producing diesel engines that were shoddy. The car he drives was a diesel produced in 1985, and it is excellent for gas mileage. Because GM produced some really crappy diesel engines in the 1980's save a few, including the one just mentioned, diesel was disfavored in the US. I am going to have to talk to him specifically, because although many of you are quite well-informed, I'm not convinced you know completely what you're talking about. The way he explained it to me was this (and I'm sure I will forget a LOT): Basically, a diesel is a long- stroke engine. Any engine that is long-stroke, and you can make unleaded long-stroke engines, has better fuel economy. It is adequate for most typical driving. -However- the world of racing has a STRONG influence on the world of cars, and so there has been strong emphasis on performance, particularly quick acceleration, etc. I asked him about diesel prices vs. unleaded-- he said something about that diesel was cheaper than unleaded, and would remain cheaper if the price wasn't set artifically higher by.. the government, I believe. hold your offenses until I talk to him.. I've listened to him a lot concerning car mechanics and history of such, and rarely can I remember it all to any good effect.
Last I heard, in Michigan anyway, gas taxes are higher than diesel taxes. This has been a sore point for a while: Diesel is primarily purchased by commercial ventures, who (seem to) have more clout in the legislature. So they avoided the road-improvement increases the rest of us have had to swallow. A few months back, I bought gas from a place that had an interesting sticker on its pumps: "Price includes $0.33 in taxes." At a time when gas was selling for $1.20 or so. (87 octane unleaded.)
Gas taxes are equal to diesel taxes, unless you're a semi truck driver. Then you get the "three axle discount" and save about 15(?) cents a gallon. Note that the price advertised by truck stops is usually the three-axle discount price. As far as #127, you're probably right about the influence of racing on cars. I'm not sure about the efficiency of a long-stroke vs. a short- stroke engine, but I can think of some reasons why that might be true. A big reason diesels are more efficient, though, is that they're unthrottled engines. A gasoline engine, unless it's at full throttle, is always having to work to pull air past a partly-closed throttle plate, and that robs some efficiency. Diesels have no throttle plate, so the intake is much less restricted. Why not have your friend look over the Escort you're thinking of buying? He sounds knowledgable about these things.
"Long-stroke" seems to be another name for "under-square", which is just a fancy way of saying the stroke is larger than the bore. The other extreme is "over-square" or "short stroke" which means the bore is larger than the stroke. Neither of these has any direct relationship to either economy or performance. Mostly it has to do with materials and stress. The more under-square it is, the more stress the piston is under, and hence, the harder it is to make one that's strong enough. The more long-stroke it is, the larger the crank case has to be, and the higher the piston speeds goes, which affects lubrication and longevity. Diesels tend to be longer stroke due to higher compression ratios which result in more piston stress. Gasoline engines tend to be generally slightly under-square, because they put less stress on the piston, and it's more important to conserve on engine size. All things being equal, an under-square engine can rev higher, which means gasoline engines generally enjoy a distinct HP/weight advantage over diesel. This gives gasoline powered vehicles a potential mpg advantage in start-stop traffic over diesel. On the other hand, diesel fuel contains about 8% more energy per gallon than gasoline, giving them an inherent "mpg" advantage, especially in highway driving where weight doesn't matter nearly as much as wind resistance. A lot of people make a big deal over "torque" instead of "HP". Torque x rpm = HP. Tranmissions have gearing in them, which means they can adjust rpm, and hence also torque. If you have a high reving engine that produces lower torque, you can compensate by putting a larger gear ratio in. What you really care about is the "HP", the shape of the power band, and the ratio between its lower & upper edge. Large motorcycle engines produces about as much if not more power than small truck engines. You'd need more gearing, because truck engines don't usually go > 2000 rpm, and many motorcycle engines go to 8K-10K+. You could get by with fewer gears, because the truck has a 1:2 useful ratio in its power band, and the motorcycle has a 1:5 useful ratio. On the other hand, the motorcycle engine will be less economical to operate, and will wear out long before the truck engine does. You can read more about bore & stroke here: http://www.g-speed.com/pbh/bore-vs-stroke.html http://www.howstuffworks.com/ and fuels here: http://www.osc.edu/research/pcrm/emissions/petrol.shtml
Re #129:
The person with the mechanic friend (Captain Lumen) and the person
considering the diesel Escort (myself) are two different people. Though I
would love to have him look at the car.
it would be fun, and a hell of an adventure. Ben is closer in Moscow, ID, but alas, is far, far busier than even I.
I have a friend who lives in Moscow, ID.
Re #131: Ah, sorry. I lost track. It'd be good to have a knowledgable diesel mechanic look it over. Among other things, a compression test would be nice. (The tool to do it is much more expensive than the one for gasoline engines.) Low compression on a diesel results in very sooty exhaust, hard starting, and poor fuel economy.
I'll see what I can do about it. Still, how good *are* the diesels in Escorts specifically?
Re #130: Under-square engines can generate more power for several reasons:
1.) They have a larger cylinder head, which means more area for
valves. Larger valves means freer breathing; more air charge
gets into the cylinder, and exhaust back pressure is smaller.
2.) The smaller stroke means lower piston speeds and accelerations,
allowing higher RPMs.
This has relatively little to do with efficiency at cruise, which
is almost always done well below redline RPM except for such vehicles
as semi trucks where that pesky 1.5:1 power band must be respected.
One of the influential factors for efficiency is, believe it or not,
length of the connecting rod. The longer the con rod is, the smaller
the angle it makes with respect to the line between the crankshaft
center and the bore center. This decreases the side forces on the
piston, which in turn reduces frictional losses from the piston
riding against the side of the cylinder. Every bit of power that
is reclaimed from friction goes straight to the output shaft.
I had a diesel tempo. It ran great. it ran awesomely. but, for some odd reason we couldn't get it to start. figured out what it was, but I can't remember now. otherwise, it was a most excellent engine. the car was rusted out and the interior was rotting away, but it was great under the hood. minus that it stopped starting. but, once you got it started it purred like a kitten and sipped fuel.
A car that runs great but can't be started is known as "disposable".
I'd suspect the glow plugs. They do eventually wear out, and a diesel with one or two bad ones is hell to start, especially in cold weather.
Re 138 - A lot of people with lots of disposable income think that way. Other people fix things that are not working perfectly and get a lot more use out of them.
Sure, but you wouldn't be able to do that if the first kind of people didn't throw them away for you to salvage.
You *can* fix your own stuff, and not add it to the "disposable" collection.
That isn't what Sindi and Jim do, though. They pick up stuff other people have gotten rid of, which requires people willing to get rid of stuff. (I'm not criticizing what they do, by the way -- I respect that aspect of their lifestyle a lot, even though it isn't the way I want to live.)
Jim also fixes a washing machine which he purchased new (about 25 years back).
I respect what Jim and Sindi do with used electronics and such as well. I got a real nice stereo from them for not very much money, also a VCR. In #138 I was referring to a car which couldn't be fixed. I've had cars like that, and had them when I didn't have much money. It's a tough situation, but that doesn't change the basic fact. If the car can't be fixed, it's disposable and you have to get another.
Just because something does not start does not mean you cannot fix it. That is probably minor compared to the body being rusted out.
re #146 Well now, doesn't that depend on why it won't start? (I have no idea what the specific car malfuntion in question is) What if it's an engine problem that can't be fixed unless you get a new engine? What if the issue involves the use of tools you don't have, or parts of the car that you really cannot access (unless you have specialty **expensive** equipment that a repair facility would have)? What if the cost of the repair is more than the value of the car? Lots of what ifs. Overgeneralization can be a very silly thing (or at least make one look silly).
Jim replaced the engine on one of his Jeeps for a total cost of $0. His housemate was borrowing the Jeep when the engine blew, found him a used car with a similar engine which he bought for $25 and sold for $25 to someone who wanted the windshield. He used the garage door and a chain to hoist the old engine out. He finally sold the Jeep when the floor rusted out, for parts. Starting problems can sometimes be cured by cleaning spark plugs.
The problem with fixing cars yourself, is you have to have the interest, knowledge, tools, space, and time to do it. I sure wouldn't trust my flimsy garage door to hold *any* sort of automobile engine, and I have limited patience with 15 year screws that have gotten rusted into place.
And as for "people with disposable income", well, if you're not competent to fix things yourself (or, sometimes, if you are), sometimes having something fixed costs a respectable fraction of the cost of replacing. (Or *more* than replacing, for some items.) If there are other expensive repairs waiting to happen, this becomes a very bad deal - in terms of your disposable income.
There's always a point of diminishing returns.
I really wanted to tell that to a group of deep greens that I saw in
an ancient and battered small truck - I think it was a Ford Ranger. There's
a point of diminishing returns, and your truck's emissions are worst than the
biggest Excurvation SUV monstrosity.
That and the time value of money. Sure you can do some of these things yourself- but when factoring cost you should also factor in how much money your time is worth. Plus, if you don't know how to fix something and attempt it- and only end up making it worse where it gets to the point where you have to bring someone in (or repair much more than was originally broken) you end up spending a lot more time and money on a project than if you just called a professional in the first place. -although, I do think that people shouldn't get too dependent on other people fixing things for them. If you have a car you should know how to change a tire, know where the fluids are and how to check them (and fill if needed). I guess my basic point is that if you can do something yourself- bravo! But, doing something yourself is NOT always cheaper than hiring someone- it just may seem like it is.
Re 2nd paragraph of #152: that's what usually happens to me when I try to fix something, especially something plumbing-related. Usually, the point at which it becomes obvious that I can't turn the house's water back on until someone competent comes in occurs about 11 PM on a Saturday.
Re #146: We once had to dispose of a car because the frame rusted out and it was no longer safe. (Well, technically we didn't junk it. We sold it to someone for almost nothing with the warning that it was only to be driven around town at low speeds.) Re #151: You have a point, but it takes a lot of driving before you make up for all the pollution created by the manufacturing process, too.
Slightly different behavior that I'd like opinion on:
I decided after all to get the Grand Am fixed, which may have been a
mistake, but it would by necessity have to include a lot of other things
done. A new thermostat was included in the deal.
The car now runs fine, and the cooling system hasn't leaked a drop.
However, the temperature (as measured by the guage) now behaves as follows:
On first startup, the temperature slowly climbs to 220 degrees, plus
or minus 10 degrees depending on the engine load, then immediately drops
to 150 degrees. On the second cycle it peaks at around 180, then drops
to 160. Thereafter if sits more or less at 170 degrees if parked and
idling, otherwise it cycles between 160 and 180, sometimes going as low
as 150 and as high as 190.
I went back to the guy who did the work and asked him about it, and he
said that was *normal* - that I should only worry if the guage reads well
above the 220 mark.
Could he be right? (It *is* a smaller engine, with less thermal mass.)
Should I make him change the 'stat? Or should I just let it go for now and
keep an eye on the engine temperature?
Also, what is a good way to determine whether the radiator fan is
working? I have never seen it turning. (This *shouldn't* have effect on
above, since most of the time (particularly the time when it's cycling)
the car is moving. But I could be wrong on that point I guess.)
You could apply power to the fan relay and see if the fan turns, but that will only tell you if the fan and relay are good, not the thermostatic switch. (On some cars turning on the A/C will also do this, but not if yours has a seperate fan for the A/C condensor.) Sometimes the switches fail completely, and sometimes they fail by letting the engine get hotter than it should before switching on. It's almost certainly working to some extent -- most cars will overheat pretty quickly at low speeds if the fan isn't turning. If you're really concerned, park the car after warming it up and let it idle. The fan will probably come on within 10 minutes if it's warm out (or the temperature gauge will climb towards the expensive side of the scale.) To this day I've never seen the fan on my car run, and it's quiet enough compared to everything else that I don't hear it either. The only way I know it's cycling is the voltmeter drops a few volts as it comes up to speed.
Is this temperature fluctuation at a standstill and idle or at speed on the freeway? If it's at idle and the drops correspond to the radiator fan turning on, you're probably just fine. If this is happening at speed on the freeway (where ram air should eliminate any need for the fan), you have a problem with air bubbles, a sticking thermostat, or a flaky temperature sensor.
Good point. You might want to try bleeding the cooling system if your car requires it. (Some don't. It depends on whether the highest point in the system is at the radiator cap or somewhere in the engine block.) If it needs bleeding, there's usually a bleed screw at the high point of the system you can open to let air escape. On my Honda it's on the thermostat housing, but it depends on the car's design.
Your cooling system probably has 3 sensors: the thermostat which opens to let more cooling water flow; the "fanstat" thermal switch which turns on the fan, & a readout for you in the cockpit. These are probably completely independent, and very likely, each measures the temperature at a different point. Assuming you run an anti-freeze mixture, a water temperature of 220 F is perfectly acceptable. The anti-freeze mixture elevates the boiling point, plus the cooling system is designed to be pressurized in operation which further increases the boiling point. These are both desirable for fuel economy reasons; it turns out you really want the cylinder wall temperatures to be somewhat warmer than the boiling point of water. (Air cooling actually has an advantage here.) In normal operation, the thermostat should be the primary means of regulating the temperature. If the car is moving at any significant speed (probably anything >30mph) the car's speed probably induces sufficient cooling air to pass without the need for any fan. The fan is mainly needed for operation on warm days with large amounts of idling and standing, and not very much moving. That's the main incentive to switching over to electric motors for the fan instead of driving it off the engine - because the need for a fan is generally not at all proportional to engine speed. On some cars, the fan continues to operate after the car is shut off. On these cars, it's quite obvious when the fan is working -- summer months at a shopping center should be a good place to spot these -- or a crowded tourist attraction. Otherwise, you might be able to catch the fan in action by letting the car sit and idle for a while (and get good & warm), then shutting the car off, then turning the ignition on without starting the car, getting out, and listening. So far as the initial huge temperature swing of your cooling system; that is not necessarily unreasonable. Until the system reaches equilibrium, it's likely to act differently. It's very likely to take longer than normal for the thermostat to open for the first time, and meanwhile, it may be possible for "hot" pockets to form that are warmer than they'll be when the thermostat is cycling at a faster rate. It's possible your engine even designed deliberately to facilitate this -- the engine will certainly warm up faster if parts of it get warmer than usual, or, if your car's heater is hooked up to a hot spot, it will deliver more heat sooner to the passenger compartment than it would otherwise. If you can get ahold of a copy of the service manual, all of these things can be tested. The thermorstat can be tested in a pan of hot water on the stove and a thermometer. The service manual will tell you at what temperature it should open and close. The fan can be tested by shorting the fanstat switch, or disconnecting it and just bypassing it with a jumper. The fanstat switch can be tested in a manner similar to the thermostat switch, although figuring out when the contacts open may be more of a challenge.
Actually, emissions requirements were one of the reasons VW got away from aircooled engines. While it's true that aircooled engines can run higher cylinder temperatures, it's harder to *regulate* the temperature accurately, which causes problems. Also, while high cylinder temps are good for economy, they're bad for certain types of emissions -- the whole purpose of an EGR system is to *cool* the combustion gases, for exactly that reason. Finally, aircooled engines are often deliberately tuned to run rich at high throttle settings, because it keeps them from overheating. The unburned fuel carries heat off with it. Imagine cooling an engine by spraying fuel onto the cylinder head, and you get the basic idea. That's part of the reason that aircraft engines are run with the mixture set full rich during takeoff, when full power is being demanded from the engine but the airspeed (and hence the cooling air flow) is low. (The other reason is that a gasoline engine gives the most power when it's running slightly rich.) Normal cylinder head temps for VW engines were in the 350 to 400 degree range, incidentally. Their larger engines had to use sodium-filled exhaust valves to keep the valves from stretching. (The sodium helped transfer heat from the valve head up the shaft to the valve guide, where it would dissipate into the cylinder head.) The displacement of aircooled engines tends to be low, partly because of the square-cube law. Surface area, which is needed for cooling, increases more slowly than volume as you increase the engine size.
I think I said "fuel economy" not "fuel emissions". I probably should have said "maximal efficiency", and perhaps even qualified that with "on a power/weight basis". There are some old and modern air cooled engines that use "oil cooling" - presumably this leads to more cooling capacity and better regulation. This includes both motorcycle engines (many of which have the same power range as automobiles), and aircraft engines (and some of the larger air cooled designs were much larger than anything people would reasonably put into an automobile (there are always unreasonable people, of course, including several attempts to stuff a liberty engine into a motorcycle.)
Propylene glycol coolant is used on some cars and allows a much higher coolant temperature (as well as a smaller radiator); the sea-level boiling point is over 350 F. If the thermostat was just changed, the most likely culprits are sticking and air bubbles. It is unlikely that a sensor would go flaky at the same time unless it had to be disturbed in the process of changing the thermostat (e.g. it is mounted on the thermostat housing). Further, 220 F. isn't far enough above the boiling point of glycol to prevent boiling at "hot spots", which decreases the heat transfer rate and lets them get even hotter. That's how metal gets warped and gaskets get blown. If the gasket has already failed, you should be able to determine this by removing the radiator cap (before it gets fully hot!) and smelling it. If you see a stream of bubbles or smell fuel, the gasket is a goner and you've found out what the problem is (gas bubbles coming from the cylinders).
Re #160: Actually, EGR systems are mostly for control of peak combustion temperatures, to which NOx formation is exquisitely sensitive. Being able to limit excess O2 is a double plus, but a lean enough mixture can cut NOx to very low levels even with a pure air/fuel intake charge and compression ignition. The biggest problem with air-cooled engines is that the relative temperature of the cylinder and piston is hard to control, so clearances have to be larger and there's more blow-by and more "quench" space between the piston and cylinder wall where unburned fuel gets stuck. That makes for some difficult HC control problems, IIRC. "Displacement of air-cooled engines tends to be low"? Uh, maybe you should talk to the 1940's and 1950's aircraft-engine designers about that. There are 720 CID flat-8 engines in use in light aircraft to this day (Cherokee 400), and radials went all the way up to 4360 CID. (I believe the R4360 was a four-row, 36-cylinder "corn cob".) About the smallest certified unit in common use is 200 CID; IIRC the smallest certified aircraft engine currently being built in the USA is 235 CID. I've owned cars with lots more power than the O-235 makes, but only one with more displacement. Re #161: Aircraft engines do not use oil cooling for anything except the pistons, and that's true regardless of what cools the cylinder walls and heads. "Oil cooling" is a misnomer.
You should let HKS know that at once. They advertise an "oil cooled head" motor, the HKS-700E, for ultralights. Obviously they're guilty of false advertising. BMW and Suzuki make oil/air cooled engines; supposedly the design is inspired by WW2 aircraft design although I don't have any detailed references. The WW2 Nakajima Ki-43 Hayabusa seems to have had a fairly impressive oil cooling system. I suppose it's conceivable if unlikely that they only used this for cooling the pistons and ran a separate non-cooled supply for the camshaft and other bearings. The idea of oil cooling is certainly older than WW2; the 1923 Orbit motorcycle could apparently be had with a 350 cc "oil cooled" engine, perhaps made by a company called Bradshaw.
Re #164: This HKS engine, it's certified by the FAA for aircraft use? What type-certified aircraft ship with it, and/or what companies have been issued supplemental type certificates to install them on certified aircraft?
I don't see the oil cooling. (http://www.hpower-ltd.com/pages/features.htm) I see no oil coolers and they don't talk about oil cooling in their 'plug'. This thing reminds me of the boxer engine in my '69 BMW motorcycle. That has oil cooled heads too, as far as I can tell. Since oil flows everywhere in an engine, it's difficult not to have oil cooling! Suzuki claims air/oil cooling in their 1462 cc, 6-valve engine in their IntruderLC VL1500.
VW engines were effectively 'oil/air cooled', though they weren't advertised that way. The oil cooler design on the Beetles and early vans left something to be desired, but the later vans had a pretty good one. I forgot about the huge air-cooled aircraft engines when I wrote that post, for some reason. I don't know what I was thinking. They did tend to have very large oil coolers and pretty involved airflow designs, though, to help cool them down. In ground vehicles it seems to be a more difficult problem. The 2.0L aircooled engines VW put in their 1972 through 1980 vans were adequately cooled, but were close to the edge -- any loss of efficiency in the cooling system (like a rag caught in the blower, or missing spark plug seals), and they would overheat. People who have bored them out for more power have found that it takes a lot of effort to keep them from melting down. It's not like a watercooled engine where you can just slot in a bigger radiator. I imagine part of the difference is that aircraft don't sit still in traffic much. ;) One interesting thing about those VW engines was that, if properly maintained, they wouldn't overheat when run continuously at full throttle. Watercooled engines generally will. The difference is that in a watercooled engine, you can rely on the thermal mass of the water for short periods of time, and the cooling system is sized on the assumption that full throttle won't be used for very long. Aircooled engines have a lot less thermal mass and can't rely on that.
Re #167: Interestingly enough, I don't think I've flown an aircraft which has had a separate oil cooler. All of them have depended on the engine compartment airflow keeping the oil pan cool. This changes when you get to turbocharged engines, but I never flew behind any. Maybe the T-6 has a separate oil cooler, but as I only flew one once and didn't do the preflight I didn't get that familiar with it. If you think about it, this makes a lot of sense for a vehicle which can typically depend on a good supply of ram air for almost any power level. Even when climbing at max power, an aircraft is not going to be in the situation of a car going up a mountain pass; it will have quite a bit of airspeed, and thus ram air. The RPM range, and thus the amount of energy converted to heat from shear friction in the oil, doesn't change terribly much either. 1900-2500 RPM is typical. The point about thermal mass is a good one. Shock cooling of air-cooled engines is a worrisome issue, and large power reductions at speed are avoided for exactly that reason. If anything, aircraft have problems at the excessive-cooling end of the spectrum.
Re #168: VW attempted to get around the shock-cooling (and warmup) issues by having vanes in the airstream controlled by a thermostat under the engine. Good point about the RPM range -- most car engines have redlines of at least 5,000 RPM, and that's just about unheard of for an aircraft engine IIRC (except for 2-cycle engines driving props through gearboxes.) I'm pretty sure most of the large aircraft engines had oil coolers. I knew a guy who was a flight engineer on a radar picket aircraft and he mentioned opening all the oil cooler doors on one side as a practical joke on the pilot. (It would cause the plane to yaw towards that side.) Didn't some versions of the Piper Cub have an oil cooler, or am I thinking of something else?
Re #169: There is (or was) a Revmaster adaptaton of a VW bus engine which is supposed to turn something like 3200 RPM in flight, but it's for use with a propeller of much smaller diameter than is usual. It was pitched at small, fast aircraft like KR-2's and Dragonflies. Dunno about Piper Cubs, I've never flown one (or even looked at one closely). However, it wouldn't surprise me to find that versions of the Super Cub fitted for use as towplanes for banners or gliders would have oil coolers (as well as rather flat-pitched climb props). The biggest engine I've ever preflighted more than once was an O-370. I don't recall seeing an oil cooler on it, but I could have forgotten; that particular aircraft crashed in Lake St. Clair years ago [carburetor ice]. Bummer, both it and the owner were very nice (his wife survived).
3,200 RPM sounds about right, since that's the torque peak of the 2.0L VW bus engine. Yellow line is at about 4,700 RPM (that's when the valves start to float with standard valve springs), redline is 5,500 RPM. Beyond that, unless you have a counterweighted crankshaft, you start to get into trouble because the crank flexes too much The Volksplane kit airplane uses a VW Beetle engine. They mount it with the fan-pulley end forwards, using an adapter hub on the end of the crank to mount a prop. They state that's to make the engine mounts easier, but I also suspect it's better internally -- the propellor thrust acts in the same direction as the force from the clutch would in the car, which is the force the crankshaft thrust bearing is meant to resist.
Did I say O-370 above? I meant O-470.
The Piper Tri-Pacer has an engine which looks like an inverted Beetle engine in it...at least it looked that way to me.
Re #171: Yeah, thrust considerations are a big deal for direct-drive aircraft engines. One of the reasons I see for using gearboxes is to get rid of undesirable thrust loads on the crankshaft. The idea of driving one's accessories off of the flywheel end is a little strange, but it does make sense in that case.
Re #173: Inverted? I think the exhausts go downward on all such engines, and of course the oil pan is on the bottom. Are the pushrods reversed? They are on the top on aircraft engines that I've seen. The one element that would definitely look inverted is the carburetor and intake manifold.
Re #174: There weren't really any accessories to drive. It was a pretty simple airplane. I don't think it had an electrical system, probably not a vacuum pump either. Re #175: VW Beetle engines have the pushrods on the bottom, so an engine with them on top might look 'inverted' to someone used to VWs. Also, I think a lot of aircraft engines have the intake manifold on the bottom, don't they?
That's what I meant. The Beetle puts the crankshaft down low to mate with the transmission, so there's very little underneath; the carb and intake manifold go on top. The aircraft engine sets the crankshaft up high to get maximum propeller diameter, so the carb goes below. The one picture I could find of an aircraft-engine cylinder showed the ports on one side and the pushrod tubes on the other.
Getting back to trivial, mundane, car care for a moment: my 1986 Subaru GL has lost the flexible air intake hose from the air intake filter housing to the heat exchanger on the exhause pipe. Coincidentally the engine now will not idle. Is this connected? There is now a little (?) less vacuum on the air intake at the carburetor, so the mixture could be leaner. Should I expect that to have killed the idle, or is losing the hose just not important? (Actually, the hose had come off the heat exhanger a long time ago, but it was about two feet long, so still caused some vacuum at the carburetor)
All that hose does is provide preheated air for the carburator, during cold starts. I wouldn't expect it to kill the idle, but it would tend to cause rough running in cold weather and maybe stalling due to carburator icing. I'd replace it (you can get the hose at auto parts stores) but I don't think it will cure your idle problem. When I have a car that won't idle at all, the first thing I look for is a vacuum hose that's come loose from the base of the carb or the intake manifold. If it will idle when cold, but not once it's warmed up, make sure the choke is opening.
There is no longer a connection for the hose at the heat exchanger on the exhaust as it came off that by connection to the latter being lost to rust. So there hasn't been heated air for a long time, with no noticeable problems. So the only question was whether the hose mattered in terms of balancing the intake pressure at the carburetor. So....I'll look elsewhere for the idle problem. About time for a regular service anyway. Thanks for the information - I presume you know the Subaru engine systems?
No, I don't know Subarus specifically. I was speaking from general experience. Vacuum leaks are a common cause of idle problems. I once had the brake booster vacuum hose come loose on my VW and it caused such a bad vacuum leak that it would only run at full throttle.
Re #178: It sounds more like you may have lost your EGR valve; the resulting vacuum leak will make the engine fail to idle. I can't see how the snorkel to the exhaust manifold heater could cause that problem, as you don't get heat for some seconds after engine start so it wouldn't idle after cranking.
I wasn't thinking about the heat but about the effective "choke" action of the snorkel (thanks for term! 8^}). I would certainly agree that there are a lot of other things that could affect the idle, especially direct controls on the carburetor, such as vacuum-based controls.
Forgot about the EGR...besides a vacuum leak, failure to idle is also a symptom of an EGR valve that's stuck open.
You have several choices: