Volvo v70 2.5t low compression in One cylinder

Eliotlm · Post by **Eliotlm** » 20 Dec 2020, 07:17

This is now my third thread on this topic but i think it deserves a new thread as it now concerns another issue. Before, 2 cylinders didnt fire, i have now fixed One of Them by replacing plugs and a coil. Then i did a compression test and concluded that cylinder 3 had really low compression, the other ones had 125psi whilst number 3 had 25psi. I heard that a burnt Valve is Common, is that a really Hard fix and even worth fixing? Do i have to pull the engine? What should i do? How do i (hopefully) Rule out Piston springs?

I should add that i only did the compression test with the engine Cold and without any oil added.

Post by **FLXC90** » 21 Dec 2020, 20:37

Next step is a "wet" compression test of the affected cylinder. Pour a spoon of oil into the cylinder, so that it can potentially seal worn rings, and re-test. If the compression comes up, rings are bad, if not, suspect valve. To repair burnt Valve, it is just a head gasket job, r&R of the bad valve, and suggested all new valve seals, lap and reinstall. Then you will be good for another hundred thousand, right?!