response 147 of 184:

Mar 6 19:56 UTC 2002

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).

response 149 of 184:

Mar 7 04:22 UTC 2002

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.

response 151 of 184:

Mar 7 15:56 UTC 2002

        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.

response 153 of 184:

Mar 8 14:02 UTC 2002

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.

response 155 of 184:

Apr 9 19:23 UTC 2002

    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.)

response 157 of 184:

Apr 10 02:09 UTC 2002

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.

response 159 of 184:

Apr 10 22:03 UTC 2002

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.

response 161 of 184:

Apr 11 19:06 UTC 2002

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.)

response 163 of 184:

Apr 12 04:16 UTC 2002

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.

response 165 of 184:

Apr 13 02:25 UTC 2002

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?

response 167 of 184:

Apr 16 16:02 UTC 2002

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.

response 169 of 184:

Apr 18 20:05 UTC 2002

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?

response 171 of 184:

Apr 19 14:28 UTC 2002

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.