Leak Down Help

[Jerz]

I hove some funky leak down numbers. The 2-6 cylinders are all good – 3-5%, but number one is low at around 20%. But when I rotate the crank, the numbers go up to normal. They are about 5% up to about 30deg before the TDC, then drop to 20%, and go up to 5% from about 30deg after TDC. My uneducated guess is that rings and piston are good, but the cylinder is scored or worn out at the very top. Am I correct? Anybody seen something like that before? What should I do next?

[E Sully]

Try to listen for where the air is escaping to narrow it down. Do you here it leaking from the intake, exxhaust, crankcase? Type of engine, mileage, etc. will help diagnose also.

[Jerz]

It's leaking through the rings, but only around the TDC. Engine is 3.6 turbo , mileage unknown.

[Steve@Rennsport]

Originally Posted by Jerz

It's leaking through the rings, but only around the TDC. Engine is 3.6 turbo , mileage unknown.

You need to take it apart to inspect the cylinders as well as measure the top ring lands on the pistons.