On the white '84 944 that I am swapping engines in, I did a compression test on the old engine before I started removal on it, so that I could see if I have something worth selling without fear of sending junk out. The engine was pretty cold, so I wasn't expecting really high readings, and was pleased to see that I had 150psi readings on cylinders 1, 3 and 4, which was exactly where I would expect a cold NA engine with some miles on it to be. Cylinder 2, however, was reading 170psi. I was able to repeat this reading testing it several times, including squirting oil into the chamber. Any guessed what would cause that? It would have to have a heck of a lot of carbon build up in the combustion chamber to effect a compression reading, right?

Comments?

Regards,

 

bump... anybody?

 

Scott, I'm no expert by any stretch but if you add oil to your compression test and the readings increase then that indicates a concern with the rings. Also, a cold test can be quite deceiving.

Can you perform a leakdown test as that will give you a much better indication of the status of the engine?

 

I did add oil and had no change. I pretty much figure a leakdown test is in order, altho it will be a cold one, as the engine is no longer able to run without having to hook everything back up.

Regards,

 

Mike B, whenever I see your avatar, I think you're Skip from Paragon...and I just read "I'm no expert..." and I'm like, "You're skip! you are an expert!, oh wait, that's not skip..."

Yeah...anyway

 

Oil leaking past the valve guide and bumping up the psi??? Did it run ok in the past?

Any indication that the head has been off?

Did you retest all the cylinders with an oil squirt and they were all the same,ie did the others stay at the same psi also?