86IROC112

OK fellas, my car has become a lot like a woman. She is frustrating me so badly I had to take a break from her. However, I still love her and think about her non stop. And absolutely can't bear the thought of someone else driving her.


So in my endless quest to solve my poor idle I did a compression check. This caused the temporary break up. #1 cylinder came in at 150 PSI. All the rest ranged from 70-95. So during all that thinking about her it made me think, how the hell could all the valves (either exhaust and or intake) have a problem on all of those cylinders, Same with the rings considering this is a freshly built motor that has been run VERY little since it's assembly 1-1.5 years ago.


I got to thinking maybe the PO didn't torque the heads down properly or enough and that compression is leaking out between the heads and the block. I have no water in my oil but figure the water is under a lot less pressure that that air.


My plan after we get back together is to first squirt a little oil into each cylinder and re-check the compression, hopefully to rule out the rings. Then I will do a leak down test on each cylinder. My question is if the air is leaking out of the head gaskets and not the valves, how will I know?


Help love prevail. I'm open to suggestions...

novaderrik

check the valve adjustment... if they are too tight, the valves might not seal and you will have little to no compression.

sofakingdom

iTrader: (1)

No way to blame that on head gaskets.


If the gaskets were sufficiently poorly sealed to cause that much of a loss of compression, your most frustrating symptom, the thing you can't solve and are looking for help with, wouldn't be "poor idle".


I agree, valve adjustment would be one of the first things to look at, especially if you haven't adjusted them with the engine running. Do it that way, NOT any variant of "twist the push rod".


Tell us what the results were and we'll go from there.

86IROC112

Sorry, should have mentioned that in my OP. I did adjust the valves with the engine running and if anything they are on the loose side.

Low compression in 7 of 8 cylinders wouldn't cause a poor idle?

sofakingdom

iTrader: (1)

Yes it might.


No it's not head gaskets.


Yes you might be able to fix it by replacing the head gaskets; by revisiting whatever was screwed up during the initial build.


No it is not likely, even though also not impossible.


Valve train is the more likely suspect.


See my signature for a mental pointer that might keep you from jumping to erroneous conclusions via "maybe it's this maybe it's that but my worst fear is [fill in the blank] so that's what it's gotta be" syndrome.

86IROC112

So say the rings didn't seat properly, could that cause that big of a loss of compression or do you think it's more likely something wrong with the valves? I have run it quite a bit in the garage trying to work this out and haven't noticed a bit of smoke??


Valves not seating properly??

novaderrik

loose valve lash will also result in low compression readings, due to not being able to move air into and out of the cylinder..

get it running and set the valves with it at a hot idle- not warm, hot.. put a few miles of driving on it and then adjust them as soon as you can... back them off until it just starts to clatter, then tighten it up until it just stops... do this on all the rockers, then shut it off and turn them all in 1/2 turn..

Night rider327

iTrader: (13)

Have you done a wet compression test yet (where you squirt a little oil into the cylinder) then test the compression)??

Low compression can be from a long list of things... Valve adjustment, cam going flat, bad head gaskets, wrapped heads, bad rings, worn cylinder bores, rings installed wrong, etc, etc.

With only 1 cylinder having good compression, to me that kind of points to valve adjustment off

86IROC112

I did it exactly as you said except I had a mechanic tell me to turn them in 1/4 turn. Could that be too loose?

sofakingdom

iTrader: (1)

No; that's fine.

When you did this compression test that's got you all concerned, did you: have all other spark plugs besides the one in the cyl you were testing, removed; the throttle blocked wide open; and the battery fully completely totally all the way charged for every cyl?

86IROC112

Yes, yes, and yes. Brand new battery. Engine was warm too. When I do the wet compression check should I make sure the motor is warmed up like it was when I did the original test?