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Grex > Cars > #121: The Winter '02 Car Care Item |  |
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| 10 new of 184 responses total. |
russ
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response 175 of 184:
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Apr 20 14:10 UTC 2002 |
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.
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gull
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response 176 of 184:
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Apr 21 02:49 UTC 2002 |
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?
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russ
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response 177 of 184:
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Apr 21 23:55 UTC 2002 |
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.
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rcurl
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response 178 of 184:
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Apr 22 05:31 UTC 2002 |
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)
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gull
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response 179 of 184:
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Apr 22 14:43 UTC 2002 |
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.
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rcurl
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response 180 of 184:
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Apr 22 19:29 UTC 2002 |
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?
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gull
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response 181 of 184:
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Apr 22 20:45 UTC 2002 |
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.
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russ
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response 182 of 184:
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Apr 22 23:37 UTC 2002 |
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.
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rcurl
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response 183 of 184:
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Apr 22 23:42 UTC 2002 |
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.
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gull
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response 184 of 184:
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Apr 23 14:34 UTC 2002 |
Forgot about the EGR...besides a vacuum leak, failure to idle is also a
symptom of an EGR valve that's stuck open.
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