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  #1  
Old 04-05-2002, 01:00 AM
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Location: nevada
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Angry low compression

just bought an 85 190e w/ 135k on the odometer. Car wouldn't start. Checked out compression and it's about 120 psi all the way around. Could that stop me from running/starting or should I look for other source of problem?

thanks for any reply
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  #2  
Old 04-05-2002, 01:12 AM
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Location: Beech Island, S.C.
Posts: 468
The compression it on the low side but that's not the cause of not starting. I would check the fuel pressure and the ignition.
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  #3  
Old 04-05-2002, 02:00 PM
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Thanks for the reply!!

I have spark on the plugs so it's probably my fuel pressure. The plugs get a coat of fuel though and I can smell fuel when you try to start it. I guess I probably have not enough spark or not enough fuel pressure.

appreciate the help
thank you
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  #4  
Old 04-05-2002, 08:33 PM
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Join Date: Jul 2001
Location: San Antone
Posts: 408
Cold compression of 120 psi is really low, 130 psi at sea level is about the minimum for the engine to start and run, as you gain altitude the compression psi goes down (take the engine's compression ratio X atmospheric pressure at the altitude where you're located - say 9 to 1 compression ratio and sea level with about 14.5 psi atmospheric pressure: 9 x 14.5 = 130.5 psi for minimum compression for an engine to work - this is just a rule of thumb and not specific to any engine). 150 psi cold compression or higher is closer to what you should have and 175 + psi hot. If the plugs are wet then it could either be not enough compression, too much fuel, fuel timing to the nozzles is wrong, the ignition timing is off (there could be other problems like the timing chain has jumped a tooth, bent valves, bad head gasket, weak coil(s), distributor is not timed to the engine correctly, etc., etc.). I am throwing out some ideas as to why your engine won't start since I don't own your model, but past experience with many other vehicles suggests my list as some of the reasons why you're having problems.

Try this, squirt a little oil into the cylinder, connect your compression gauge to that cylinder, and spin the engine to see what the reading is. If the compression remains the same with oil then the valves are suspect and if the compression goes up then the rings are bad. If the valves are bad then you can pressurize the cylinder and then listen to see which valve leaks - use a stethoscope, a screw driver, a piece of wood (like a cut off broom handle), or perhaps just your ear to listen for where air is escaping - out the exhaust pipe is a bad exhaust valve and out the intake/air cleaner is a bad intake valve, and a bad head gasket can have bubbles/air escaping out the radiator.

Perhaps another member or a moderator has the "silver bullet" fix for your problem - like something in the electronic control system.

Good Luck!
Tom
__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.

Last edited by tcane; 04-05-2002 at 08:55 PM.
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  #5  
Old 04-06-2002, 12:10 AM
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Thanks Tom.

I tried the oil squirt on each cylinder and compression went up just a bit, 5 to 10 psi. Do you think I have bad rings or would this indicate either valve or head gasket problem. I wanted to do your sugestion on pressurizing the cylinder but I don't have an air compressor at hand.

thanks for the help!!
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  #6  
Old 04-06-2002, 01:17 PM
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Join Date: Jul 2001
Location: San Antone
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Dan:

A rise of 5-10 psi shows the rings are not sealing like they should, but really bad rings would show a 20 psi or more increase. It is going to be difficult to do more diagnostics on the cylinders without compressed air. There appears to be something wrong with the engine (a timing chain that has jumped a tooth and/or bent valves can also show low compression, in addition to a bad head gasket). Since you have even low compression in all cylinders I'm leaning toward valves and/or the timing chain has jumped a tooth - something along these lines anyway. A blown head gasket will usually show 1-2 bad cylinders and not all cylinders being equally low on compression.

It can be really hard to diagnosis a problem via email when you can't do more tests (I recall a person cussing me out when I could not ID the problem with his engine by listening to it over the telephone and he refused to bring it to the shop because he claimed we would rip him off repairing things that did not need to be fixed - true story!).

Is the starter turning fast enough to start the engine? It sounds like the car has not run for a while and a push start will get the engine turning fast enough to possibly start. However, if there is a mechanical problem with the engine push starting could do more damage (but, then again maybe not if the engine is already damaged - the rock and hard place position). If you try push starting, make sure you can get the car back home if the engine fails to start.

I suggest that you continue to inspect the things I listed. Do you have a shop manual to help with specs needed to inspect relationships/condition etc. to determine what the problem is? The Haynes manual for your model probably has a good trouble shooting section - the ones I've looked at do, but I have not looked at the Haynes manual for your model.

It may come to having to do a TDI (tear down and inspection) to find the problem. However, personally I would want to do more tests to see if something else is the problem since 120 psi compression is close to minimum needed for an engine to run and it sounds like this car has not run for a while.

Perhaps another member has had a similar problem and can help you.

Good Luck!
Tom
__________________
America: Land of the Free!

1977 300D: 300,000+ miles

American Honda: Factory Trained Technician & Honor Grad.
Formerly:
Shop Foreman;
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.
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