91 Legend Engine Smoking

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Rick - 06 Mar 2006 06:08 GMT

My 91 Legend has 174,000 miles and is smoking and I suspect it is worn
valve guides (it only smokes on starting and while sitting at a stop
light). Several mechanics have said when repairing the valve guides,
you also need to repair the bottom end of the engine (or just get a
newer engine). The reason given is that when the top part is repaired,
it will give more power and then the weakened bottom end might fail
also.

I tend to disagree with this but would like some expert opinions. I
recently did several full acceleration runs of 0 to 60 and clocked
about 8.2 seconds - slightly slower than the original 8.0 seconds. If
the bottom end was weak then it would have failed under this full load.

So the main question is: Is it reasonable to just repair the valve
guides and leave the rest of the engine alone - is the Legend engine
strong enough to just have to repair the top part? I would of course do
a leak down test and compression test to validate my theory. Of course,
if a complete engine overhaul cost just a few $100s more than just the
valve guides, I would do that.

2nd question:
Can the valve guide repair be done without removing the heads? On some
engines, you can use compressed air to help do the job. My mechanic
says he would not know until he removed all the equipment above the
heads. Any advice on this would be appreciated.
Thanks, RIck

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James S - 06 Mar 2006 09:03 GMT

there are 2 possible reasons for the smoke;
1. guides, as you suspect
2. piston rings.

Doing a leak down/compression check will help determine if its the rings, or
the valve stem guides/seals. If the cylinders are at good relatively similar
compression, its likely the stem seals/guides; cause there's no oil getting
past the piston rings. The symptom for the valve guides, is that it smokes
only when you start the car, but not idling at the red light...at least
according to what I read online. This would make sense if the exhaust
valve(s) is the culprit, leaking oil has no chance of burn as it gets blown
out to the muffler.

I had smoke with my 88 L coupe.(idle, stomp throttle=poof) Had a compression
test done, one of the cylinders was 10% lower than the others.

I read in Honda Tuning magazine an article doing valve stem guide/seal
replacing on an Integra, that it was done w/o removing the heads...only the
valve covers and up were removed.

Even though trusted mechanics are tricky to come by, I would try to find a
tech that HAS done the job w/o removing the heads. If thats not possible,
compare the math with a complete eingine swap.

good luck, hth.
J

> My 91 Legend has 174,000 miles and is smoking and I suspect it is worn
> valve guides (it only smokes on starting and while sitting at a stop
[quoted text clipped - 22 lines]
> heads. Any advice on this would be appreciated.
> Thanks, RIck

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duckbill - 06 Mar 2006 14:05 GMT

Rick, I had the same dilema when rebuilding my son's 87 Toyota Supera (non
turbo). He was going through some oil and the head gasket was starting
to fail. Had smoke on start up until the cat. converter warmed up. Valve
guide seals were brittle and the oil rings (only) were frozen on 4 of 6
pistons. Compression rings were doing their job wonderfully. That would
also be a good time to replace the connecting rod bearings. Have you tried
Castrol GTX high milage oil? It's working great in my 95 Civic EX with
192K.
Good luck.

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Acura God - 08 Mar 2006 01:08 GMT

I recently put valve seals and headgaskets on my 91 Leg LS. The engine was
smoking before I did the work but now it does not smoke at all. I only had
about 225 bucks in parts invested to get the job done. You will not hurt the
bottom end replacing seals/guides. By the way my car has 218k miles on it
and the cylinder still has cross hatching visible in them.

David Short
Acura God

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