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Concerned about valvetrain noise

E

Ecarlcl

NAXJA Forum User
Location
Huntington, NY
I just picked up a 91 XJ, 4.0, 5 Speed, 160k. It runs great but It makes a noise that I would consider to be a loud tick almost a clunk. It doesnt really become audiable until it gets close to operating temperature. I know these motors are prone to make some noise with piston slap and all but this is way louder. It's not exhaust I know that for certain. (I know what that sounds like from my old renix) I probed around with a long screwdriver and narrowed it down to the top end. Sounds like the rythm is at half engine speed so I think its a sticky lifter. I've been doing some reading about sticky lifters and it seems like everyone has their own method with oil types and additives to try and quiet them down. I was just planning on adding some sea foam to the crank case to see if that does anything and changing oil again in like 1000 miles. I was just wondering if anyone had any input before I did that. Should I switch it over to synthetic? Ive also read on the board about taking the valve cover off and starting it to try and get a better diagnosis. Can you run the motor with the valve cover off? Wouldnt oil spray everywhere? Just a little confused about all the additives and oil types on the market for high mileage motors.

Thanks
 
i also have this same problem and am curious what people wills ay.l I think I am going to pull the valve cover off and look under there
 
Ecarlcl said:
I just picked up a 91 XJ, 4.0, 5 Speed, 160k. It runs great but It makes a noise that I would consider to be a loud tick almost a clunk. It doesnt really become audiable until it gets close to operating temperature. I know these motors are prone to make some noise with piston slap and all but this is way louder. It's not exhaust I know that for certain. (I know what that sounds like from my old renix) I probed around with a long screwdriver and narrowed it down to the top end. Sounds like the rythm is at half engine speed so I think its a sticky lifter. I've been doing some reading about sticky lifters and it seems like everyone has their own method with oil types and additives to try and quiet them down. I was just planning on adding some sea foam to the crank case to see if that does anything and changing oil again in like 1000 miles. I was just wondering if anyone had any input before I did that. Should I switch it over to synthetic? Ive also read on the board about taking the valve cover off and starting it to try and get a better diagnosis. Can you run the motor with the valve cover off? Wouldnt oil spray everywhere? Just a little confused about all the additives and oil types on the market for high mileage motors.

Thanks
Click to expand...
Diagnosing noises over the 'net is tough, unless LOTS of detail is given, specifically WHERE in the engine the noise is coming from. Do a broomstick to the ear trick to isolate the region of the engine for the noise.

Running the engine without a valve cover can be done, but it will spray oil all over the place while doing so--very messy.
 
I wasnt really asking for a diagnosis I was just wanting some info on the remedies....
 
I understand now. I would start by trying to clean the valvetrain with some additive, or a mix of ATF and motor oil run in the engine for a while. That might loosen up a sticky lifter.

If that fails, the valve train on the 4.0 is pretty straightforward, with one caveat--to replace any lifters, the head must be removed, as there is insufficient clearance to drag a lifter out of the gallery through the pushrod holes.
 
it could but ive only seen it happen on engines with a true solid lifters ... the hydraulic lifters in your 4.0 are pretty much idiot proof but it doent mean they cant go bad and and pump up anymore causeing a noisy lifter/ ticking or your clunik sound is very possable with 160 k on it depending how weel it was taken care of... 4.0's dont like dirty oil and really dont like it when they dont have there oil changed... bad things do happen...

01, 00, and 94 xj limiteds
rollin in rugged style
 
I had a noise that I was 98% sure was cam and lifter related....turned out to be a very worn out mechanical fan clutch and pulley bearing....took it off and ran with out it and the noise went away

What I'm saying here is don't overlook the accessories as possible noises.
 
I'll try taking the serp belt off next time I get a chance. I dumped half a can of sea foam in the oil today. Could'nt hurt right?
 
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