1 dead cylinder

F

Feral

New Member
Joined
Apr 29, 2021
Messages
7
Location
Earth
My Jeep is a 93 YJ with the 4.0 6 cylinder multiport fuel injected.

It has been lacking power.

I just checked the compression and #1 was dead.

1 - 0 psi dry/wet
2 - 130 psi dry
3 - 115 psi dry
4 - 130 psi dry
5 - 135 psi dry
6 - 130 psi dry

I am not losing coolant, my oil does not have water in it.

I think it is either a stuck or burned out valve.

I could see the valves moving, but not how they were seated in #1.

I am going to try a really good fuel additive and see what happens, but I think I am going to need to replace the valves, I will probably do the entire head.
 
Sounds like a burnt valve like you indicate. 0 is odd as you typically get something be it worthlessly low. Wonder if you had/have a leaking intake on #1 causing a massive lean condition. About the only thing to do is yank the head, inspect the piston top and have the head done. Guess if you were really motivated you could see if the valves are closing 100% on #1. If not it could be a bent valve stem. My experiance the burn and look like a pie with a slice missing which may also deformed it enough to hold it from closing all the way and leak out the missing slice hole.
 
Top Bottom