Hello!

My 2002 4.0 187k on the odometer had the slight rattle at cold startup and I replaced the tensioners with primed OEM Ford tensioners. A couple days later, it had the check engine light turn on for my last mile of my drive home. . P0300, P0301, P0302, P0303. The engine was running very rough and almost sounded like it was rattling. Entire bank is misfiring, making me think it jumped timing. I think something was off with the rattling initially, and the new tensioners progressed the damage. I'm fully aware of the death rattle and the timing system of this motor, which made me replace the tensioners thinking it may prevent the death rattle.

I garaged it and am ready to pull the engine and replace the chains and components. I do not want to compression test it, risking damaging the valves if they are not damaged already, if the engine did indeed jump timing. Is there any way to check if valves are good without having to crank it? I want to ensure I'm not wasting my time and money replacing the chains if the engine is toast. It starts up (I do not start it since the incident) but idles very rough. If it starts up, is it still good to replace the chains?

Did I wait too long to address the timing chain issue? Any input is appreciated.