90 renix dead cylinder
Thread Starter
CF Veteran
Joined: Dec 2011
Posts: 1,050
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From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
See what others think. Hydro-Lock was mentioned besides pre-ignition. I might just change out the bent push-rods. (you role them on a flat surface to check). Agreed with Cruiser Btw, just pre-ignition was mentioned googleing, and that's what the knock sensor is there for. A stretch though. If I had sucked in water and had bent pushrods, I'd just install straight push-rods. (yes, likely the reason for low compression).
Oh, AND install a knock sensor.

Oh, AND install a knock sensor.
Thread Starter
CF Veteran
Joined: Dec 2011
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From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
Ok. By pushrods we are referring to valve/lifter rods correct? Stupid question but just want to verify.
And the proper method should be Tdc on compression stroke for each cylinder, torquing the rockers to 21-25 ft b right?
And the proper method should be Tdc on compression stroke for each cylinder, torquing the rockers to 21-25 ft b right?
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
CF Veteran
Joined: Aug 2011
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Now it's my turn to ask questions. Can't the lifters get pumped up so much you need to loosen rockers, then gently pull them back down?
A bent push-rod brings up an uncommon situation as it had the opportunity to run and pump it up (the lifter), too high.
Sounds goofy I know, but at least one poster years ago ran into that. I'm not sure the lifrers are desinged to give up ground they made that easily.
A bent push-rod brings up an uncommon situation as it had the opportunity to run and pump it up (the lifter), too high.
Sounds goofy I know, but at least one poster years ago ran into that. I'm not sure the lifrers are desinged to give up ground they made that easily.
Thread Starter
CF Veteran
Joined: Dec 2011
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From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
Lifter rods were replaced, fired it again, running rough as all get out but saw that the body ground got caught under the valve cover, I'll sort that out tomorrow and try again. Also, still need to 're test compression to see if the new rods have improved the compression
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Lifter rods were replaced, fired it again, running rough as all get out but saw that the body ground got caught under the valve cover, I'll sort that out tomorrow and try again. Also, still need to 're test compression to see if the new rods have improved the compression
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Thread Starter
CF Veteran
Joined: Dec 2011
Posts: 1,050
Likes: 2
From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
I want to say 3 for sure, possibly 4. I didn't roll them on glass or a flat surface but just by naked eye you could see at least 2, the ones on cylinder 4 were bent enough to be rubbing the head through their range of motion, the rear rod on cyl 3 looked a little iffy, and possibly the one on the front of cyl 5. I'm thinking when I "hydrolocked" the motor when we were mudding is probably what caused them to bend, however the failure happening at least 2 months later is what gets me.
Anyways, as I said all rods were replaced, still haven't got over to it to check compression with new rods, work has me a bit caught up until wendsday, I'll try to sneak a look at her tomorrow afternoon, in the meantime, what's your speculations cruiser?
Anyways, as I said all rods were replaced, still haven't got over to it to check compression with new rods, work has me a bit caught up until wendsday, I'll try to sneak a look at her tomorrow afternoon, in the meantime, what's your speculations cruiser?
Thread Starter
CF Veteran
Joined: Dec 2011
Posts: 1,050
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From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
All cylinders are still at the same pressure they were at, with 4 still only pushing about 20-30 psi. I'm noticing that this brand new plug has a good bit of oily residue on the tip. I'm going to assume it's a valve being cracked more then likely, but cruiser, I'm all ears to your suggestions, since you have been dead on so far


