engine noise - 2002 3.7

[jeeptorino68]

hey guys, i need some help with a strange engine noise
2002 3.7 limited (45RFE) approaching 200,000 miles

there is a strange growling, knocking, rubbing type sound when running noticeable at lower RPM but im sure its there at higher, i just cant hear it over the engine...
happens in all transmission gears.
it is coming from the front of the jeep (IE transmission area and forward)

the noise is hard to describe, it comes and it goes, i havent found anything associated with the coming and going of the noise.
it seemed quieter when the clutch fan engaged (i have the HD cooling package) but maybe that was just the noise of the fan muffling it...


any thoughts?

 

[ltd02]

That's a tough one without being able to hear it. I assume you checked all the belt drive bits? If not maybe remove the belt and run it for a few seconds to see if the sound is gone? Wiggle all the pulleys while the belt is off too. :shrug:

 

[jeeptorino68]

Yea this one is Wierd for sure. Removing the belt is easier said than done when you have the HD cooling fan. But I might try that
It is easier to hear from the top of the engine I think

 

[jeeptorino68]

It is a fairly inconsistent clunking rubbing scrubbing type of sound, doesn't seem to have a patter. Could happen 3 or 5 times in a row, or could happen once.

 

[ltd02]

I had a different vehicle that made that type noise when the belt tensioner was weak.

I hear you on the belt removal. I have the HD cooling too.

 

[jeeptorino68]

Was going to pull the belt tonight but need a bigger wremch, borrowed my dad's last time

 

[uss2defiant]

cut a notch at the bottom of the shroud and you'll be good.
best mod I ever did.

 

[jeeptorino68]

I want to say it's probably the belt tensioner or a bearing on the a.c. or the alternator because of the randomness of the noise. I would be more inclined to think it is the valve train if the noise was consistent.
What do you all think?

 

[ltd02]

I want to say it's probably the belt tensioner or a bearing on the a.c. or the alternator because of the randomness of the noise. I would be more inclined to think it is the valve train if the noise was consistent.
What do you all think?

I'd agree with that inclination. I've got a little chatter from my timing chains when cold but steady noise and completely disappears within a couple minutes. If you haven't done it, the notch trick that uss2defiant mentioned works great to pull the shroud.

 

[uss2defiant]

could use a mechanic stethoscope to listen to how those pulleys are doing so you dont have to pulley the shroud out.

 

[jeeptorino68]

I can't remember, is the clutch fan nut a 36mm?

 

[ltd02]

Yes. I just went and double checked on mine.

 

[jeeptorino68]

Thanks

 

[Conundrum2006]

Harmonic balancer?
Those can make all kinds of weird sounds when the rubber begins to fail

Belt tensioners also cause all
Kinds of noises


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[jeeptorino68]

picked up a real mechanics stethoscope today at lunch, hopefully that will give me more information tonight on the noise location.

the harmonic balancer appeared to be running straight and true. no wobbling

 

[teeje]

Money is on the tensioner. What I did was take phone and point it at the tensioner and hit record. Go in the jeep and turn the Ac on and off until I heard the noise. Watched the video and it was the tensioner making all the noise.


2002 Jeep Liberty 3.7L with brand new engine
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[jeeptorino68]

Looks like it's the tensioner. The ribbed pulley barely spins

 

[jeeptorino68]

Well that pulley was bad but the noise is still there. It is in the belt drive though because without the serp. Belt there is no noise

 

[jeeptorino68]

More endless information. Noise is there with or without the clutch fan. Noise is there after replacing the tensioner and both of its idler pulleys (gates brand) I can't seem to pinpoint it to any other pulley or device. Power steering, alternator, ac, balancer, water pump.
Any culprits more likely than another? The alternator I suspect has been replaced by the PO. The pulley has marks on it from being messed with. And it is denso which I don't think would be factory is that correct?

 

[teeje]

Do any of the pulleys have play?


2002 Jeep Liberty 3.7L with brand new engine
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