Mike815

First time poster. I have been using these forums forever. helped so much on my 1992 cherokee and now has helped a ton on a 2000 I have.
im not a mechanic just mechanically inclined. i read stuff here, i watch some videos, i try it. if i get stuck i watch some more.

this is a 2000 jeep grand cherokee 4.0, automatic. 4wd. Think I posted in the wrong section but I don't see how to move it. sorry.

It all started with a cylinder 5 misfire and violent shaking while 50-60mph as well as bad idle. I chased down everything. injector, coil pack, both o2 sensors, im sure theres more that I can't recall. everything in that misfire thread thats around here somewhere.
Ended up doing a compression test. all cylinders 130+ psi except for cylinder 5. 20psi. put a little oil in the cylinder, still 20psi.

when I removed the cylinder head I found antifreeze in the cylinder along with the little bit of oil i put in there for the test. figured it was a cracked head (right? anything else other than head gasket that would cause that?) but i cant find the crack in the old head. whatever, i already bought the new head so on it goes....
replaced cylinder head with a TUPY. all new gaskets, etc.
almost had everything reassembled when I noticed the one rocker above cylinder 5 is loose after torquing. i can flick it and it sounds like a jingle bell.
lifter isnt stuck, i can feel the spring when i push up and down on the push rod. there are a couple more that are a little loose, I can compress the lifter with the pushrod. but not loose like the one above cyl. 5. when i turn the engine over a few of them tighten up. the really bad rocker tightens up a little bit but not tight like the others. at its worst its still tight enough where the rod wont come out from under the rocker.

compression test time.
25 psi on cylinder 5...

im going crazy now...
when this problem started i lost like half a gallon of coolant, but my oil wasn't over the safe limit so im wondering how bad the oil really got anyway. probably drove like 1 hour total after discovering this problem.
the overall engine temp never overheated on the gauge.

did I possibly ruin my camshaft? I want some extra input before i rip it all apart again. I think I know the answer since I ordered new gaskets already and am getting ready to do it all over again.

I did NOT start the jeep back up after all this because i figured it would just get worse. should I?
also I dont want to waste the new coolant just to drain it. and new oil just to drain it.. im a little lost right now. thought I was all done with the new head.
where do I go from here?

Turbo X_J

The camshaft could have had a wiped lobe to begin with, is the lift on both #5 I & E similar to the others? (rocker arms move up and down the same amount?)

Mike815

I’m not sure the difference on intake and exhaust for the rockers. The loosest rocker is the 3rd from the firewall. The 4th feels good.

Bugout4x4

Two other possibles... Is the pushrod straight? and does it look like the valve stem head is as tall as the rest when the valve is closed?

Mike815

Rod looked good. I switched it with a tight one just to check. Switched them back. Switched the rocker with a tight one, still nothing. Changed it back.
.
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Bugout4x4

If the pushrod is loose you can spin it with your fingers and it will be very obvious if it's bent. Yes the valve stem head would be above the spring where the rocker pushes. I have gotten rebuilt heads where the wrong valve was installed and either too short or too tall. This could throw off the valve timing so that it is not opening or closing when it should to build the proper compression.

Mike815

Yes the rod is loose. I can almost pull it out from under the rocker. Bent rod is out since I swapped 2 rods and the problem stayed in the same spot. (I put them back in the original spots after) .

5-Speed

Do a leakdown test before you go any further. That will tell a lot. If the leakdown comes out good, its probably just a lifter issue. If it comes out bad, well then you got to find out what is leaking and the leakdown test will point you in the right direction.

Jeepin'_Aint_EZ

This is the best advice to take right now. You need to see what's causing the low compression. I'm leaning towards a bad lifter but won't know anything until you perform a leak down test

Mike815

Thank you for the advice, everybody who has replied.

so after reading about leak down testing what you guys are getting at is that you want to see if the cylinder is either:
not able to pressurize itself by engine (possible lifter)
or not able to hold the pressure (something else?)

is that about right?
I'm trying to get my hands on a compressor, not much luck yet
and possibly buy one of those harbor freight testers..

Turbo X_J

Maybe you can rent an air compressor, beware the HF gauge tho...

Bugout4x4

I think your camshaft is fine, like others have mentioned it sounds like a collapsed lifter. The oil port in the side is probably plugged. A lifter properly filled with oil should be hard as a rock if you try to push by hand. There should be no give or spring to it at all by hand. But there is something you could try before you pull the head to access it. But it takes air pressure even if you just rent or borrow an aircan and a blow gun.

A collapsed lifter is not always a bad lifter... It's just stuck inside and needs to be unstuck and then will work and be fine after it's back up and full of oil. What you can do is mark the pushrod right at the head line where is goes through to use as a height guide and blow good air pressure down through the pushrod into the lifter a few times. If it unsticks it you will see the change at your mark.

It might take numerous tries but I have done it this way before. But this is real important... If you get it unstuck, it will need to be filled with oil before you bolt it back down with the rocker and pushrod. You will need to disable the ignition so it wont start and turn the engine over a few minutes with the starter to pump oil up into the lifter. Then take the pushrod and use it to "pump" the lifter spring up and down until it gets impossible to push the spring anymore and the lifter feels hard like it should.

Once it is back up and solid like it should be, you should be good to go and can bolt it back together.

5-Speed

Yes you are on the right track. When you do the leak down test, you will be able to hear the air coming out of 3 different places. The oil fill cap (bad rings or cracked piston), the throttle body (bad intake valve) or out the exhaust pipe (bad exhaust valve). If the test comes back good (less then 10%) then its most likely going to be the lifters.

Yes beware of the HF tester. I personally have a Matco leak down tester. Yes it was expensive but it is super accurate and a very valuable tool to have. I would not trust any of the cheap ones. Same goes with mostly all other tools that need to be dead nuts accurate. Mics, dial indicators, bore gauges, straight edges, TQ wrenches....

Mike815

Thanks again for the replies.

so the air compressor I got is awful. barely any pressure to blow into the pushrod. I didnt open the leakdown tester because I figure this compressor isnt able to provide enough air for a test even.

I tried blowing some air, a little carb cleaner. a little marvel mystery oil down towards the lifter. (though idk if those last two would be any help)
i can still pump the rod up and down by hand, feels like its on a spring. can hear oil squishing around in there too.
I have been cranking on the starter. the pushrod got tight one time but right away came loose again. I made these 2 videos to show what is going on.
anything else I can try?

when I hold down the pushrod it still kicks up and down, just not when there is no pressure on it.
lifter? still possibility of cam?

videos:

Thanks

Turbo X_J

In your first video, the fact that oil came through the push rod would mean the guts are still in the lifter. At this point it would be prudent to pull the head and actually see what's happening in there.