I am looking at a 98 with a CTSC and during the PPI one cyclinder only had 120 PSI compression. Car only has 36k. Owner is hoping valves need adjusting and is having it done. Anybody have any thoughts on this.
Low compression on one cylinder
- Thread starter sippy2
- Start date
I guess not likely a valve adjustment issue.
That's too bad...not for my sake but the owner.
What could it be?
That's too bad...not for my sake but the owner.
What could it be?
- Joined
- 31 December 2010
- Messages
- 309
Why didn't the inspector issue a leak down test? It would have taken another 10 minutes of his/her time and would be able to tell you the most probable cause. Heck, I would have done it just from curiosity.
It could be something as simple as carbon deposit not allowing a valve to close fully, or it could be something much worse.
It could be something as simple as carbon deposit not allowing a valve to close fully, or it could be something much worse.
He did a leak down and it was at 15%. I should have included that.
I thought when I posted...the horror stories would come flying...guess this has not been an issue with anyone else.
BTW he mentioned possible carbon deposit...how is that addressed?
I thought when I posted...the horror stories would come flying...guess this has not been an issue with anyone else.
BTW he mentioned possible carbon deposit...how is that addressed?
For general knowkedge on the board...we did a valve adjustment and that brought the compression up.
Brought it up how much? Is it inline with the others?
Yes...the others were between 145-155 and this one is now 145.
I just bought a 1991 NSX and it ran fine when I picked it up. After driving it the way it should be the next day it was running rougher. I did a compression check and one cylinder was at 160 while the others floated around 185 to 200. Looking inside the spark plug hole it showed carbon build up so my brother blew compressed air back through the compression checker and then when re-tested it went to 180 psi. My car has 85000 kms (Canadian car) and I believe by driving spiritedly it had dislodged some carbon. The previous owner never drove the car very much and I doubt he ever did a top speed run or come close to redline.
I would think the combustion process would be much more powerful than the compressed air to blow out the carbon....
I am not an expert but one of the valves may not have been sealing properly because of the chunk of carbon. Whatever the air did it worked. Misunderstanding I know compressed air will not clean off carbon buildup that is why we used combustion chamber conditioner in the throttle body to help with the cleaning process after.
Last edited:
