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Old 12-01-2012, 08:13 AM   #1
Mlewisjr1035
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lost compression on cyl 2 time for a rebuild.. any suggestions

well fellas it finally happened sitting in the bank parking lot depositing money my 2006 IBM m6 started to run rough. what i originally thought was a bad plug or coil turned out to be a loss of compression in cyl 2 all others read 190-200 and cyl 2 was at 115...DAMN.... gonna pull it out later this week and check the extent of trhe damages. if the car gods are smiling hopefully i can get away with honeing, re-ring and bearings.... well i have about 2000-2500 to put into rebuild. car already has kooks longtubes, spintek exhaust, fast 92mm intake, underdrive pulley, 160 thermostat.
so i guess my question is for about 2500 including machine work,what would mods yall recommend?
im planning on a cam, not sure which one, ive heard good things about england green cams.
was thinking of getting the heads worked, or possibly ls3 top end.


any input would be greatly appreciated, and if anyone has any parts that would be useful in my rebuild PM me thanks in advance yall
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Old 12-01-2012, 08:16 AM   #2
Mlewisjr1035
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forgot to mention car has 66000 miles on it ... ive owned it for a year and put about 8000 hard miles on it.... never any other problems that werent user error... car had nitrous on it by the previous owner, guessing thats why the compression ring gave out so early
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Old 12-01-2012, 08:18 AM   #3
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Have you tried a wet compression test? If you are lucky you may have had a injector fail and wash down the cylinder. Kinda seems like you are going to a drastic remedy, before performing proper diagnostics.
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Old 12-01-2012, 08:25 AM   #4
Mlewisjr1035
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bobbygoat1

not sure what u mean by a wet compression test
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Old 12-01-2012, 08:57 AM   #5
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It could also be a valve not sealing too. Might be something as simple as a flake of carbon stuck on the valve seat. I would not assume it's rings until the heads are off and you've done a good inspection.

A wet compression check is when you squirt oil into the plug hole and run a compression check. If it increases the compression, then it's probably the rings. This is not a completely accurate indication because of the cylinder angle on V8 engines. You should jack up the side of the car on the bank you are working on. A leak down test might be better.
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Old 12-01-2012, 09:04 AM   #6
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Quote:
Originally Posted by Mlewisjr1035...View Post
bobbygoat1

not sure what u mean by a wet compression test

A wet compression test is the same as a regular one, except you add a few teaspoons of oil to the cylinder you are testing to check the rings.. Here is a link to compression testing, and how to interpret the results. http://www.team-integra.net/forum/bl...1-faq-how.html Its not a GTO, but it is still a good explanation. Hope this helps you out.
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Old 12-01-2012, 09:09 AM   #7
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To do a dry compression test you need to have the engine at operating temp. Disable the fuel relay and disable the ignition spark, and have the throttle body blade held open and crank the engine about 4-5 revolutions and get your compression reading

For a wet test remove the spark plug and add about a teaspoon of motor oil in the cylinder and repeat the above procedure.

If your compression readings stay the same you more than likely have a problem in your valve train, if the compression reading goes up by about 25% or more you have a piston or piston ring or cylinder issue.
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Old 12-01-2012, 09:18 AM   #8
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what if the leak in the rings is at the high spot in the cylinder and all the oil runs to the low spot? Then a wet test tells you nothing under those circumstances.
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Old 12-01-2012, 09:28 AM   #9
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Quote:
Originally Posted by batboy...View Post
what if the leak in the rings is at the high spot in the cylinder and all the oil runs to the low spot? Then a wet test tells you nothing under those circumstances.

Then you do a leak down test.

If you put a teaspoon of oil in the cylinder and spin the motor 4-5 revolutions as I said the compression will definitely stay the same or rise a significant amount, any other questions?

What is your suggestion? Batboy? Remove the engine and completely disassemble it and maybe find, yes it needs a rebuild or possibly find it was something that could have been fixed easily without removing the engine.

That's what proper diagnostics are for and the difference between a mechanic and a parts changer!
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Old 12-01-2012, 09:33 AM   #10
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I am just saying a wet test may or may not be valid. I offered some suggestions back in post #5. I gave a tip to improve the wet compression test results and I said a leak down test would probably be better. If after doing both the dry and wet compression tests and then even leak down test, you will probably still need to pull the head off. The man has low compression in cylinder #2. There is a problem. Just saying.
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Old 12-02-2012, 12:13 PM   #11
Mlewisjr1035
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culprit is a broken valve spring on intake of cyl 2
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Old 12-02-2012, 12:16 PM   #12
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Originally Posted by batboy...View Post
It could also be a valve not sealing too.

Post #5
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Old 12-02-2012, 03:11 PM   #13
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Quote:
Originally Posted by Mlewisjr1035...View Post
culprit is a broken valve spring on intake of cyl 2

Stock valve springs? At least it's an easy fix.
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Old 12-03-2012, 03:01 AM   #14
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Hope intake valve didn't meet piston crown.

Replace all the valve springs.
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