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Discussion Starter · #1 ·
Hello all!
I need some help tracking down an engine tick on my 98 Jeep Grand Cherokee. I just got done cleaning the engine bay, replacing the plugs, wires, and distributor cap & rotor. The engine turns over great but I'm noticing a pretty substantial engine tick. I linked a video below so you can hear it. Before the parts replacements, the tick was there, however it seems louder now. This may be due to the fact that I was sticking my head in the bay after starting to look at the work.

 

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Man thats a loud tick.
How many miles on the engine?
Does the tick subside when the engine is hot?

From the video to me it doesn't sound like a rod knock.
Might want to pinpoint the tick area with an auto stethoscope or similar.

Some things off the top of my head:
One or more of the flex plate bolts came loose
An exhaust manifold leak which is common which can be caused by bad engine mounts.
Broken off piston skirt or piston slap if the engine has high mileage
Lifter gone bad or rocker arm came loose
 

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Discussion Starter · #3 ·
Man thats a loud tick.
How many miles on the engine?
Does the tick subside when the engine is hot?

From the video to me it doesn't sound like a rod knock.
Might want to pinpoint the tick area with an auto stethoscope or similar.

Some things off the top of my head:
One or more of the flex plate bolts came loose
An exhaust manifold leak which is common which can be caused by bad engine mounts.
Broken off piston skirt or piston slap if the engine has high mileage
Lifter gone bad or rocker arm came loose
185,XXX miles on it. The tick seems to be coming more from the top end than anywhere else, and subsides when the engine heats up and on revving. Someone else mentioned the exhaust manifold too, I'll be checking that soon. Here in the next few days I'll be pulling the valve cover off and checking/replacing pushrods and rocker assemblies for good measure.
 

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Good plan!
Yeah i forgot to mention a bent push rod, check those rockers carefully for any looseness.

Keep in mind though that ticking with a cold engine that will eventually quiet down when the engine reaches operating temperatures could be piston slap.
Typically piston slap has a deeper type tone almost approaching a rod knock which per your video i don't see it but its a video with who knows what kind of frequency response.

My old '94 XJ's 4.0 had piston slap that sounded like a diesel idling.
But that was at some 350K miles.

Good luck and keep us updated.
 

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Discussion Starter · #5 ·
Good plan!
Yeah i forgot to mention a bent push rod, check those rockers carefully for any looseness.

Keep in mind though that ticking with a cold engine that will eventually quiet down when the engine reaches operating temperatures could be piston slap.
Typically piston slap has a deeper type tone almost approaching a rod knock which per your video i don't see it but its a video with who knows what kind of frequency response.

My old '94 XJ's 4.0 had piston slap that sounded like a diesel idling.
But that was at some 350K miles.

Good luck and keep us updated.
If one of the rockers is loose is there any harm in just re-torquing it back down? Or would it necessitate replacing? I'm having trouble locating rockers locally and would like to just get it done.
 

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The concern is if a bent push rod is causing the rocker looseness. Could also be a bad or sludged up lifter or worse but highly unlikely a worn down cam lobe.
Is there a lot of sludge build up in the valve cover and the cylinder head?

If one of the rocker's is loose and tightnig it per spec. doesn't work, the rocker and the push rod need to be removed to see if the push rod is bent. Not a big deal replacing a bent push rod.
If the push rod is not bent then you could try tightning the rocker per spec. and see what happens.
If you pull more than one rocker completely off from different cylinders they should go back on the same cylinders they come off of.
 

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Discussion Starter · #7 ·
The concern is if a bent push rod is causing the rocker looseness. Could also be a bad or sludged up lifter or worse but highly unlikely a worn down cam lobe.
Is there a lot of sludge build up in the valve cover and the cylinder head?

If one of the rocker's is loose and tightnig it per spec. doesn't work, the rocker and the push rod need to be removed to see if the push rod is bent. Not a big deal replacing a bent push rod.
If the push rod is not bent then you could try tightning the rocker per spec. and see what happens.
If you pull more than one rocker completely off from different cylinders they should go back on the same cylinders they come off of.
I'll definitely be checking the rods to ensure they're straight. So if I'm understanding correctly, provided nothing is bent I should be able to just re-tighten a loose rocker? If a pushrod needs replaced do I need to replace the rocker as well?
 

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The rockers have no adjustment. They're either tight or they're not. If they're not tight, tighten them - damage might be done though. I would also suggest running the engine without the valve cover to see if you can isolate the noise as being from the top end.
 

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I'll definitely be checking the rods to ensure they're straight. So if I'm understanding correctly, provided nothing is bent I should be able to just re-tighten a loose rocker? If a pushrod needs replaced do I need to replace the rocker as well?
Ideally the rocker should be replaced with a new push rod but likely you likely could get away with using the original rocker.
Rockers and push rods over long mileages wear in together.

Keep in mind if the tick is localized with a good push rod and doesn't go away after tightening the rocker per spec. you're probably looking at a bad or sludged up lifter.
If thats the case might try an oil sludge type remover but be careful and follow directions exactly.

Like IAmTodd and i said earlier try to localize the tick as much as possible ideally using an auto stethoscope if the tick area is not readily apparent.
However like IAmTodd said, once removing the valve cover with engine running the culprit cylinder could be very obvious.
 
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Something else to add, some 4Ls were known to blow off the piston skirts. I'm not familiar with how difficult it is to remove the oil pan on a ZJ but it might be worth dropping to inspect if the valvetrain turns up ok.
 
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