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89 4.0 developed a knock...

P

Paul R

NAXJA Forum User
Location
So Cal
On my drive out to Apple Valley my 89 XJ developed a knock. WHen your not under a loac it sounds find, but under acceloration, it knocks. Oil is full and clean. It has had low pressure reading sence I bought it.

Any ideas?? Things to check??

HELP!!!


Thanks,
Paul
 
Thats wat I was thinking. Any way to find out for sure??

Looks like I will have to have it towed home.....

TIme for a rebuild or another jeep! Only had this onefor 2 months... :dunno:
 
Drain the oil out of it. Then run it back home...(how far is that from Apple Valley?) If it makes it, you should rebuild the engine. If it doesn't make it, you should rebuild the engine.
:D

I'm kidding.....but you knew that, didn't you? ;)
Rather than a rebuild, how much would it cost you for a junk yard pull?

:dunno:
 
If you rev it in neutral and you get a knock it's usually rod bearings. If you get a knock under a slight load it's usually the mains. Either way, it's time for a rebuild.

Sorry.

Maybe it's stroker time. :D
 
I agree with what Richard had to say. When you drain the oil, and pull the filter off you might want to cut the filter open to see whats inside. It may not resolve the problem, but it's another way to analyze.
Good Luck, Russ
 
I dont know that it would be that easy to put an HO(91) in where his Renix(89) is.

Stroker time!

I have 200K on my 88 and Im just waiting to have that happen to mine.

KH
 
Hey paul, check the torque converter bolts, my brother's old 91 started to knock under a load, and the converter bolts were loose...after that the thing never made another noise.
 
I started it this morning and it knocked on start up and then stopped. I took it for a short drive and no knock.. It does knock when I start it after letting it set for a while, it does this for about 1 sec then stops.

This does not make any since at all. I am planning to drive it home tomorrow early and hope not to have any problems.

Anything I can look at?? I did have the rear main seal replaced a few weeks ago.

I am totally puzzled that it stopped this morning.

Thanks for the ideas.

Paul
 
That is typical of a bad low end, rods or mains, mostly mains. It knocks until the oil circulates and the pressure builds up. When I check out an old car, I really hope to start it when it's cold to see if it knocks. They won't always knock once they warm up, until they are pushed hard after they are good and warmed up when the oil thins out.

Sorta sounds like what yours is doing. BTW, how many miles on it?
 
267K miles on it...

I'll have to pay attention to it tomorrow on my way home tomorrow.

Hope I make it!!!.

Thanks,
Paul
 
Paul R said:
267K miles on it...

I'll have to pay attention to it tomorrow on my way home tomorrow.

Hope I make it!!!.

Thanks,
Paul
Click to expand...

Throw a can of STP in it to raise the oil viscosity. It will knock a few seconds more when you first start it up, but it will keep the oil thicker after it heats up and might help to get you home.

Good luck, :wave:
 
Jump This said:
We can make...um.....accomedations for that!!
Click to expand...
x2
:firedevil
Kyung
 
Goatman said:
Throw a can of STP in it to raise the oil viscosity. It will knock a few seconds more when you first start it up, but it will keep the oil thicker after it heats up and might help to get you home.

Good luck, :wave:
Click to expand...

NO NO NO... I did that a few years ago with 302 Ford I was driving across country. My wise dad said to try that but after I did, it barely made it 5 more miles. Upon teardown, theory = STP got behind the damaged bearings and helped them spin in the journals. No more STP for me.

If I were this guy, I wouldn't be too quick to jump to bad bearings. Flywheel and any number of things can cause knocking noises that might be described as similar to loose bearings. It could be, but might also be a lot of worry for nothing.
 
XJXJ said:
NO NO NO... I did that a few years ago with 302 Ford I was driving across country. My wise dad said to try that but after I did, it barely made it 5 more miles. Upon teardown, theory = STP got behind the damaged bearings and helped them spin in the journals. No more STP for me.

If I were this guy, I wouldn't be too quick to jump to bad bearings. Flywheel and any number of things can cause knocking noises that might be described as similar to loose bearings. It could be, but might also be a lot of worry for nothing.
Click to expand...

Sounds more like sticking hydraulic lifters if it stopped shortly after start up. Have you chaged the oil and filter since you bought it?

What brand and spec oil and filter is on it right now?

Could be a problem with the oil filter, and or oil.

What are the hot, cold, idle and cruising speed oil pressure(s).

These older engines are well know for dangerous sounding valve system hydraulic lifter noises that sound like a knock. Many here have run them for years after they started making that noise. Hard to tell from the sound which one it is.
 
I added some Lucas oil stabelizer and drive it home. When I got it home I was able to check it out a little further, I also have a neighbor that is handy. He came over and after looking and listening and him driving it around the block, it sounds like the noise is coming from the vave train.

When I pull the valve cover off and check things out, can the lifters be removed through the valve cover??

Thanks for the ideas. I will be pulling it apart sometime this week after work.

Thanks again,
Paul
 
Paul R said:
I added some Lucas oil stabelizer and drive it home. When I got it home I was able to check it out a little further, I also have a neighbor that is handy. He came over and after looking and listening and him driving it around the block, it sounds like the noise is coming from the vave train.

When I pull the valve cover off and check things out, can the lifters be removed through the valve cover??

Thanks for the ideas. I will be pulling it apart sometime this week after work.

Thanks again,
Paul
Click to expand...

I think you can check for loose bolts holding the tapets on the rocker with just the valve cover off. Beyond that requires pulling the head and manifolds I think(?).

I would just add some Marvel Mystery (MM) oil to it periodically to help clean and loosen the lifters (like a half quart to start and 1 pint every 1000 miles for a while). Change the oil filter regularly and let it go. These 4.0 Jeep engines run forever with that valve train noise. Seems to be noisiest in cold weather start up. MM oil helps with that.

Also make sure you have a quality oil filter that has a working antidrain back valve. NAPA gold, Mobil 1, K&N and a few others seem to be the best, but stay away from private labeled Fram and Fram filters.

By the way, you did not answer my questions about the oil filter, oil and oil pressure that asked earlier? They relate to the condition of the engine and its bearings.......
 
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