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kewpie79 · Posted: Sat Sep 03, 2005 4:45 am Post subject: engine woes

Finally have spark. Will crank, backfire and turnover, but will not start completely. Took it to a mechanic (towed). Stated the engine is probably dead since two of the cylinders are extremely low on compression. Also said he added oil and it held its pressure for awhile, but then went down again. I'm clueless at this point. He said he is going to try to pull it and see if it will start in second gear and hopefully the rings will re-seat themselves. If this doesn't work, do I need an entirely new engine, or can it be rebuilt? Or are there any other tricks to consider?
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1980 Porsche 924
1984 Pontiac Grand Prix
2003 Kia Sorento

Jazzerpet · Joined: 07 Apr 2003 Posts: 186 Location: Omaha, NE.

How long has the car been sitting?

The reason I ask is I have found the top rings busted on two different engines that have not been started in 3 years. On the up side the cylinder walls were not scored and the rings for an NA are easy to find. The fuel distributors on both were gummed up and prevented starting as well.
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1980 931
1985 ½ 944
Member of the “Omaha Crew”

kewpie79 · Posted: Sat Sep 03, 2005 5:36 am Post subject:

it had been sitting for a couple of years.
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1980 Porsche 924
1984 Pontiac Grand Prix
2003 Kia Sorento

Ozzie · Posted: Sat Sep 03, 2005 7:27 am Post subject:

Low compression can also be valve timing not set correctly.
I'd check and double check valve and ign timing
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Lizard · Posted: Sat Sep 03, 2005 10:10 am Post subject:

ign timing would not affect compression,
however if the timing belt was off a tooth or two that would affect compression, but would do it to ALL cyl,

I would ask the mech what all the cyl compression #'s were first, and then I would do a leakdown test to see if it is a burnt valve, blown headgasket, or sticky rings.
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3 928s,

kewpie79 · Posted: Sun Sep 04, 2005 8:20 am Post subject:

thanks for the input and help.
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1980 Porsche 924
1984 Pontiac Grand Prix
2003 Kia Sorento

Ozzie · Posted: Sun Sep 04, 2005 9:17 am Post subject:

Joes924Racer · Posted: Sun Sep 04, 2005 9:31 am Post subject:

if its all timed right and still does it & fails a leakdown test it
should just need a rering job done on all pistons...easy thing to do
to the 924. You dont even need to take the engine out ... just the pistons
Im wonderen what thatll cost to have done in a N.M. shop verses doing it yourself. parts should only be about in the 250.00 to 300.00 range
youll need a head gasket pan gasket and maybe a intake gasket
the rings new oil and maybe some sealent. & the tools of course if you wanted to do it yourself. Youmight encounter some broken bolts along the way in the exhaust removal though I dont think you would
have to remove the manifold youd just need to undo the downpipe
from it. Youl also need someone strong enough to lift the head off
with the manifold in place. Myself Ive found it to much to lift off the head with the intake and exhaust in place so I remove the intake.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Joes924Racer · Posted: Sun Sep 04, 2005 9:32 am Post subject:

Incorrect timing would lead to a failed leakdown test though
or compression test. make sure its timed right.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

CBass · Joined: 03 Nov 2002 Posts: 2807 Location: Vancouver, Canada

The oil is added to verify whether the rings are bad or not. If the numbers go up for a while when oil is added during a compression test, it means the rings are toast.

The engine can be rebuilt by a chimpanzee, barring machine work.
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'81 931 in various states of assembly