Thread: Tdi Compression figures what should they be?

Originally Posted by thrower78

Hi All,
I am getting a pre purchase inspection done on a 98 tdi Disco with 160,000 on the clock what should the compression figures be approx? If anyone knows what they should be close to that would be great, the only part I know is that they should be as even as possible?

Thanks Andrew

Hi Andrew, 450 to 500Psi is on the upper range, UN oiled. DO NOT OIL A DIESEL ENGINE FOR A COMPRESSION TEST. Some do, and good luck to them. I would only do it AFTER a dry test reveals low figure, and then I would only add a small amount of oil.(Read SMALL) to isolate a valve or ring problem.

around 350 Psi is quite low, and I would suspect poor valve clearances or compression ring issues.

BUT, a compression test on a 300Tdi won't give you the full picture, the easy first up method of testing these engines is to see how they start from cold. Any Tdi that will start readily without glowing and runs smoothly is in pretty good nick compression wise. Basically,If you have to glow it to get it going, then there is a problem.
You are welcome to Ph me at work on 0408 995 635 at the time of inspection to discuss further if you need to.

JC

Awesome, figured that the oilers usualy beetween 22-27/1 compression would be up there, then add forced induction, How cold would it have to be before glow was required.