I have a 01 jeep Cherokee with a 4.0 in it. there is no compression in any of the cylinders. the rocker arms are all moving I have replaced the cam and crank sensor along with the computer. I have checked the timing gears and the chain they are fine. this use to be my daily driver and ran well until the motor just shut off going to work one day. Help me please

 

Blown head gasket? How's the coolant and oil look?

 

fine... no oil in the coolant, no coolant in the oil

 

What are the compression readings? Did it just quietly shut off one day, or was there any odd noise? Getting spark, fuel?

 

the compression is 0 on all cylinders .. I know it sounds crazy and thought my tester was bad so I put it on my other car to make sure it wasn't broke. the day it broke down it wouldn't go faster than 50 than quietly shut off. even now when I attempt to start it the engine isn't making any funny sounds

 

Dang. This is out of my pay grade. Warped head? Cracked block? Both highly unlikely, but so is having 0 psi on all 6 chambers.
I'm sure someone that's more knowledgable will be along shortly to give some input.

 

Usually having no compression at all happens when timing is off, but if yours is still right then I'd say the head or the engine itself is done. Did it overheat when it died?

Try doing a leakdown test instead of a compression test, takes the starter and other factors out of the equation. Parts stores should rent them

 

Why?

 

Bizarre. Assuming your measurements are correct, there's no way to really know without pulling the head, much less fix it.
Last time I saw zero across the board was a broken timing belt and bent intake valves..but neither apply to the 4.0

 

Deleted post - stupid question after re-reading your first post (rockers are all moving).

 

Valve timing is off.

There is NO other way to have 0 compression on all 6.

 

Exactly. NONE of those things have anything to do with compression.

Stop throwing parts at it.

Diagnose it. Test it. Have a REASON for what you are doing. You can't afford to spend hundreds of dollars doing things that can't possibly do any good.





I have to agree. Even if the engine had overheated badly and collapsed every ring in every cylinder, you'd still get SOME compression.




How did you check them? What did you check? If the chain slipped it might look fine, but you'd still be badly out of time.

What have you done to check the valve timing?