2000 Jeep 4.0 lifter help

ltrpilot9

ltrpilot9

Well-Known Member
Joined
Oct 15, 2012
My son brought home his 2000 Jeep Cherokee 4.0 making a horrendous knocking noise. The screw driver test says its in the front of the engine. I pulled the valve cover and from front to back, the first 3 rockers are loose. I can wiggle them so they rattle, the next two are tight, the next two are barely loose, and next 3 are tight, the back two will barely wiggle.
I know they should be tight. Can I re-torque them? If not what’s next?
 
That’s what I was thinking, so it’s not a good thing at all that 5 of them are loose, and 3 are really loose.
 
I’ve seen one or two lifters go bad, but never this many, which makes we wonder why? I’m thinking it’s an oil pressure problem? Oil pump? Cam bearings?
 
They probably ran crap oil and never changed it.

Most oils within last 10 years don’t have enough ZDDP for flat tappet camshafts.

Probably lost the lobes on the cam.

Run rotella oil. Has more zddp that others. Blue bottle has the most, followed by silver, then the white bottle.

Probably need a new cam and lifter set.
 
I’ve had this Jeep more than 10 years, it was mine before I gave it to him and I still do the scheduled maintenance. I’ve never run Rotella, but I run synthetic oil in all my vehicles and I have never had a problem. With that said, I’m looking for advice on what ya’ll think the problem might be, and help anyone else in the future that has a similar issue. For now I plan to pull the head and the pan and see what we find.
 
You probably have a busted piston skirt. If you pull the oil pan you can see.

You can do a leak down test that may help isolate. You can also pull an injector wire one at a time and see if the noise goes away when you is that cyl. While running.
 
Jeff B said:
You probably have a busted piston skirt. If you pull the oil pan you can see.

You can do a leak down test that may help isolate. You can also pull an injector wire one at a time and see if the noise goes away when you is that cyl. While running.
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number 5 esp. for the win.
 
How would a broken piston correlate to a bunch of loose rockers? I’m not saying that’s not the problem, it just seems to me that a lot of noise coming from the top end and loose rockers probably point to something else. But, I’m the one here asking for advice and I appreciate your time and advice.
 
ltrpilot9 said:
How would a broken piston correlate to a bunch of loose rockers? I’m not saying that’s not the problem, it just seems to me that a lot of noise coming from the top end and loose rockers probably point to something else. But, I’m the one here asking for advice and I appreciate your time and advice.
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Piston skirts break pretty easily and can go unnoticed. If you are having a bunch of bad lifter noise then I wouldn’t be shocked if a cracked or broken piston skirt is in there too. I had a collapsed lifter in my 2000 WJ for about a year then it went kaboom :D


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The torque spec on the rocker bolts is approx 24 ft/lbs. You can absolutely torque them regardless of cam/crank position. They're non-adjustable hydraulic.
The cam lobes love to wear prematurely on 2000s era 4.0 engines. If the rocker bolts are tight, but the rockers are loose, you have worn cam lobe(s).
Check those and report back. The skirts do break off as was mentioned
 
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ltrpilot9 said:
I’ve had this Jeep more than 10 years, it was mine before I gave it to him and I still do the scheduled maintenance. I’ve never run Rotella, but I run synthetic oil in all my vehicles and I have never had a problem. With that said, I’m looking for advice on what ya’ll think the problem might be, and help anyone else in the future that has a similar issue. For now I plan to pull the head and the pan and see what we find.
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Synthetic oil doesn’t equal zddp.

In the late 90s most oems went to roller lifters or overhead cams. This meant the oil didn’t need as much zddp.

Zddp is bad for catalytic converters.

With the epa focus on cleaning up emissions and less need for zddp bc of designs, most oils had the zddp reduced.

Have to get racing specific or diesel oil mostly to get zddp quantities high enough to protect flat tappet lifters and cam lobes.
 
ltrpilot9 said:
. For now I plan to pull the head and the pan and see what we find.
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Before you shotgun it, I'd check the rocker bolt torque so you can rule out cam lobe wear. If the lobes are worn, then the cam bearings are trashed. At that point, the cost to re-bearing it will be higehr than a reman unit.
Been down that road numerous times in the past.
 
Ok everyone, I really appreciate the help.
I re-torqued each rocker lobe to 24ft/lbs. That didn’t change anything on the rockers. To clarify, I can move them enough to rattle front to back not up and down. Shouldn’t they be be rock solid in any direction? Also, it appears all the rockers are working as they should.
Right now it’s got about 60PSI at the fitting near the filter. I ran it for a few seconds with the valve cover off to see if oil was coming up through the top. It wasn’t.
If you want to see a video of running, PM me your number or email and I will send it. Thanks everyone!!
 
If you have 60 psi, you're doing well for an old 4.0
Upload that video to youtube and post the link here.
 
Yup, broke piston. Classic.
 
ltrpilot9 said:
What’s the best way forward for a broken piston? Pull the pan and look for damage?
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if it was me and I wanted to keep this jeep running. I would pull the front grill and condenser/radiator, then pull engine and tranny out all together. Separate and either find a replacement or rebuild the existing engine.

you can get a fairly good rebuild kit for about 600$ and your looking at about 1K in machine work. The replacement may be easier then rebuilding for you, seems like I saw a 4.0 in the for sale section for about $350. Can't remember who had it for sale.
 
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