Bad Rings?
06-03-2007, 05:22 PM
#1
TECH Fanatic
Thread Starter
Bad Rings? I know this might not be the best section for this (non-LS1) but it is not engine specific and I already tried this over in the general maintenance and repairs section and have not gotten any bites...
I want to know something before I scrap this (P.O.S.) car…
A buddy gave me a car to fix and resell. The car is an 80’s Pontiac, that belonged to his father. About three years ago, the car over heated and warped a head, so they replaced the heads and installed a new (hydraulic)camshaft. After they put the motor back together the car ran for a few hundred miles before eating the new cam (they did not nitrate the cam or use E.O.S. on initial start up). After this the parked the car with the intake manifold off for about two years. Fast forward to the present,
He told me it needed a cam replacement and that’s it… so I replaced the cam (pushrod motor put the cam and crank at 6 and 12) and spun the motor over by hand with no interference. I cranked the motor and nothing. (Checked the compression and made about between 70-90psi) As it turns out the cam was 180o out, so I tore the motor back down and aligned the cam with the timing tabs (again spun the motor over and over and over to check, check and recheck the cam alignment). Again I reassembled the motor and it would not start. (Re-checked compression and made about the same compression) So I after my first disappointments, I started checking all the regular stuff. I checked the injectors, spark, cleaned fuel system, etc. etc.
The car still won’t start. As a last ditch effort I pulled the plugs out and put oil in the plugs and poured some oil in the cylinders, low and behold, I rechecked the compression and it made 125-155psi…
So I assume that means the rings are bad. Is there any way that a valve is bent, or I have some other compression problem, or does the oil pretty much confirm that the rings are bad?
Cliffs Notes: put oil in cylinders and the compression jumped up 50 psi, does this mean my rings are bad, or could there be another problem?
I want to know something before I scrap this (P.O.S.) car…
A buddy gave me a car to fix and resell. The car is an 80’s Pontiac, that belonged to his father. About three years ago, the car over heated and warped a head, so they replaced the heads and installed a new (hydraulic)camshaft. After they put the motor back together the car ran for a few hundred miles before eating the new cam (they did not nitrate the cam or use E.O.S. on initial start up). After this the parked the car with the intake manifold off for about two years. Fast forward to the present,
He told me it needed a cam replacement and that’s it… so I replaced the cam (pushrod motor put the cam and crank at 6 and 12) and spun the motor over by hand with no interference. I cranked the motor and nothing. (Checked the compression and made about between 70-90psi) As it turns out the cam was 180o out, so I tore the motor back down and aligned the cam with the timing tabs (again spun the motor over and over and over to check, check and recheck the cam alignment). Again I reassembled the motor and it would not start. (Re-checked compression and made about the same compression) So I after my first disappointments, I started checking all the regular stuff. I checked the injectors, spark, cleaned fuel system, etc. etc.
The car still won’t start. As a last ditch effort I pulled the plugs out and put oil in the plugs and poured some oil in the cylinders, low and behold, I rechecked the compression and it made 125-155psi…
So I assume that means the rings are bad. Is there any way that a valve is bent, or I have some other compression problem, or does the oil pretty much confirm that the rings are bad?
Cliffs Notes: put oil in cylinders and the compression jumped up 50 psi, does this mean my rings are bad, or could there be another problem?
06-03-2007, 07:20 PM
#2
Often times when an engine gets really not, hot enough to warp a head, the rings will seize on the pistons. If a compression check shows low compression, and the wet compression test after jumps up 50psi like you stated on ALL cylinders, rings would be the only cause.
