If you have no compression at all on two cylinders and low compression on the one in between them. It can only be valves. Either stuck open, burnt or the cam is so worn it is not opening them at all. There is no way it can be losing that much pressure past slipped liners. It is highly unlikely that two pistons have broken up and one is starting to break up all at the same time.
dont go giving a conclusion until the heads off. Its never a done deal until you can have a proper look. Good luck as if your doing the work good on ya. Nothing to loose !
Running wise. The engine did not sound that bad. No knocking, a little lumping perhaps. Will start stripping it down when I get home from work today.
No compression on two cylinders and hardly any on another. Think your definition of lumpy maybe slightly differ from mine.![]()