AC / pulleys/ serp-belt noise?

kccrd · **Joined:** Thu Mar 08, 2007 10:35 pm **Posts:** 267

When you say you greased all the pulleys what do you mean? Did you take them all off and clean them and then put grease in the center of the pulley then put the center piece back in then bolt it back to the engine. Please explain. Since you are in nevada and the desert you have very little humidity don't you think that could effect your belt somewhat?

KeighJeigh · **Posted:** Mon Sep 01, 2008 2:47 am

I replaced my viscous fan clutch this evening - which went fine - but since it was dark when I finished I was checking out the belt behavior using a flashlight which can sometimes be informative since it focuses everything on the subject. What I found was my belt bouncing around more than I thought. I then started up my wife's 06 and watched them side by side. Even with the AC cycling, her belt was perfectly stable and smooth while mine looked like it was about to jump off the tracks every time the AC kicked in. I then looked at the tensioner: Hers just slightly vibrated while mine looked like it was shaking violently. I noted this the last time I tried to diagnose this problem but then became convinced it was due to the alternator pulley.....I'm now wondering if I might have 2 problems happening simultaneously: A bad tensioner and a bad alternator pulley. And perhaps one caused the other.

The problem I'm having with the idea that it might be a bad tensioner is the same problem I had with the viscous fan clutch: There isn't much to go wrong with it. Unless the spring breaks in which case it would have no tension, what the hell can go wrong with it? Especially installed in a car that only has 37K on it and has been babied!

Whatever the problem is, I'm sure the solution will cost me at least $400 and a week of my time by the time it's over.

mrkake · **Posted:** Mon Sep 01, 2008 4:12 am

kccrd wrote:

When you say you greased all the pulleys what do you mean? Did you take them all off and clean them and then put grease in the center of the pulley then put the center piece back in then bolt it back to the engine. Please explain. Since you are in nevada and the desert you have very little humidity don't you think that could effect your belt somewhat?

Sure: let me elaborate. I removed all the pulleys & blew out the dust with a compressor. Then I pried out the rubber seal from each one and put a small amount of high temp grease on the bearings and I also place a thin coat inside the center ring. Then I pressed the seals back in and replaced them. All the pulleys have the same part numbers stamped on them. So I just put them back without regard to their original location.

The dry air and dusty conditions do cause rubber and plastic to deteriorate faster, but not appreciably so. That's why I replaced the belt first. The old one looked fine (no signs of glazing, cracking or splitting) and it was perfectly pliable in every way that I could see.

mrkake · **Posted:** Mon Sep 01, 2008 4:35 am

Quote:

I'm now wondering if I might have 2 problems happening simultaneously: A bad tensioner and a bad alternator pulley. And perhaps one caused the other.

I am wondering exactly the same thing. I have noticed that my belt does vibrate quite a bit. I may just replace both and hope for the best.

dgeist · **Posted:** Tue Sep 02, 2008 9:18 am

mrkake wrote:

Quote:

I'm now wondering if I might have 2 problems happening simultaneously: A bad tensioner and a bad alternator pulley. And perhaps one caused the other.

I am wondering exactly the same thing. I have noticed that my belt does vibrate quite a bit. I may just replace both and hope for the best.

Excess tension or drag on the belt (like from a dying alternator pulley) will cause the jumping. That's why the spring tension arm (and not just an adjustable pivot) is there, so the belt doesn't get shredded in two hours.
I think that's why my dealer ordered both. Tensioner pulley squeaks all the time, probably since it's been over taxed and worn out by all the jumping. Fixing the problem might stop the noise for now, but that pulley is probably on its way out shortly thereafter. I can appreciate the dealer working things like that. It only costs a few dollars more for them and saves me a trip later, which I call GOOD service. The alternator replacement better fix the root cause, though, because as of yesterday I have an ABS problem and I don't want to have to deal with both at the same time...

Dan

KeighJeigh · **Posted:** Wed Sep 03, 2008 4:00 am

FYI: Hall Auto will sell the tensioner pulley for $50. This is a hundred dollars less than the local dealer quoted me!

Quote:

05 Liberty Diesel, Tensioner pulley p/n 5072441AA - $49.00 + 8.00 Shipping.

Turbo Tim · **Posted:** Wed Sep 03, 2008 10:04 am

Well I decided to check my alternator pulley last night. Very easy to do.
I just stuck a screwdriver (very carefully) into the side, near the very back, and pushed on the air vanes. They are made of metal and if you don’t try to turn the engine over, they won’t break off.
Anyway it rotates very easily in one direction and will not go the other way.
So mine does only go one direction and made no noise. I’ll assume that it’s good for now.

dgeist · **Posted:** Wed Sep 03, 2008 10:58 am

Turbo Tim wrote:

Well I decided to check my alternator pulley last night. Very easy to do.
I just stuck a screwdriver (very carefully) into the side, near the very back, and pushed on the air vanes. They are made of metal and if you don’t try to turn the engine over, they won’t break off.
Anyway it rotates very easily in one direction and will not go the other way.
So mine does only go one direction and made no noise. I’ll assume that it’s good for now.

How fast did you spin it? Doesn't it go like 3x crank speed under power? I'm not thinking pushing it with a screwdriver would make it stand up and bark if it's going out. Mine did give a definite cyclic (few times a second) grinding noise with the stethoscope/screwdriver test. :wink:

Turbo Tim · **Posted:** Wed Sep 03, 2008 3:57 pm

What I did only checks the functionality of the one-way clutch action of the pulley.
The real test would be to remove the alternator and take it to a real alternator shop and have it tested. By testing I mean a “Full Load,” max load output test.
To check the pulley, remove the electrical load and stop the machine. The inertia of the alternator’s rotor should keep on spinning with the pulley stopped. Note if it makes noise when this happens also.

dgeist · **Posted:** Wed Sep 03, 2008 4:10 pm

Turbo Tim wrote:

What I did only checks the functionality of the one-way clutch action of the pulley.
The real test would be to remove the alternator and take it to a real alternator shop and have it tested. By testing I mean a “Full Load,” max load output test.
To check the pulley, remove the electrical load and stop the machine. The inertia of the alternator’s rotor should keep on spinning with the pulley stopped. Note if it makes noise when this happens also.

That sounds more like it. I was beginning to wonder about you, tim...

As an aside, the dealer just called and has replaced my alternator and tensioner pulley. I'm not complaining since it's free. They did tell me that they'll need to open up the diff to replace the wheel speed sensor, so I just faxed the page in the shop manual that tells them how to do it (one bolt). I hope they're not insulted.

KeighJeigh · **Posted:** Fri Sep 05, 2008 2:59 am

A hundred bucks from Hall auto online for both the alternator pulley and the tensioner pulley. That's a d@mn good deal & less than 1/2 the price of the stealer.
- C

dgeist · **Posted:** Fri Sep 05, 2008 8:58 am

I picked up the CRD last night and the dealer did not disappoint. They replaced the tensioner due to worn bearings the alternator pulley and shaft (I think that's just the whole thing) due to "out of round rotation causing uneven belt path and excess vibration", replaced the rear wheel speed sensor (malfunction killed the ABS and my odo), opened up the diff to inspect the sprocket thingy that the sensor senses (which was more than I expected them to do) and re-hung my rear diff vent line (which was hanging down). The engine sounds great and so far I've been able to observe a mpg or 2 better, I suspect due to a lot less vibration up-front.

It was one of the sloppiest RTV seals I've ever seen, but for free, I'm simply glad that it was replaced, as it was due anyway, and that it was free

Hooray for my new favorite dealer. They may still do things a little slowly, but at least they're honest and thorough. I now have 3k miles to break everything else that'll need warranty replacement.

cerich · **Posted:** Fri Sep 05, 2008 10:20 am

dgeist wrote:

I picked up the CRD last night and the dealer did not disappoint. They replaced the tensioner due to worn bearings the alternator pulley and shaft (I think that's just the whole thing) due to "out of round rotation causing uneven belt path and excess vibration", replaced the rear wheel speed sensor (malfunction killed the ABS and my odo), opened up the diff to inspect the sprocket thingy that the sensor senses (which was more than I expected them to do) and re-hung my rear diff vent line (which was hanging down). The engine sounds great and so far I've been able to observe a mpg or 2 better, I suspect due to a lot less vibration up-front.

It was one of the sloppiest RTV seals I've ever seen, but for free, I'm simply glad that it was replaced, as it was due anyway, and that it was free

Hooray for my new favorite dealer. They may still do things a little slowly, but at least they're honest and thorough. I now have 3k miles to break everything else that'll need warranty replacement.

What dealer? it is always good to know which dealer does a good job in the neighborhood!

dgeist · **Posted:** Fri Sep 05, 2008 11:11 am

cerich wrote:

What dealer? it is always good to know which dealer does a good job in the neighborhood!

Nalley Jeep(in Roswell, north metro ATL). I purchased from Jasper Jeep originally (about 1 hr north of ATL). They're great folks and I love to give them business, but when there's a good dealer 15 minutes away...

KeighJeigh · **Posted:** Sun Sep 07, 2008 12:44 pm

Both the tensioner pulley and the alt clutch pulley will be here mid-week......I should know by the end of the week if this problem is solved....

CATCRD · **Posted:** Sun Jan 18, 2009 12:42 pm

Turbo Tim wrote:

Well I decided to check my alternator pulley last night. Very easy to do.
I just stuck a screwdriver (very carefully) into the side, near the very back, and pushed on the air vanes. They are made of metal and if you don’t try to turn the engine over, they won’t break off.
Anyway it rotates very easily in one direction and will not go the other way.
So mine does only go one direction and made no noise. I’ll assume that it’s good for now.

I tried this test on my two CRDs. My wife's, which has a squeaking from the front of the engine, will not turn in either direction. Mine, which sounds quiet, will turn in one direction. I take it this means her alternator pulley is bad.

It's pretty easy to see the difference in the two jeeps at idle. Just watch the belt tensioner with a flashlight. Mine is almost still - just a little twitch every second or two. The tensioner on hers is moving so fast it's blurry.

I also noticed a little runout in the alternator pulley when I had the belt off of the squeaking jeep. I didn't check mine for runout. Both jeeps have about 37k miles.

P.S. To get the belt off I used the trick suggested here of vice grips on the end of a box end wrench to get enough leverage on the tensioner. I couldn't get the tensioner out of the engine bay without removing the power steering pulley. I oiled the spring in the tensioner, and the noise is reduced about 50%. Looks like some warranty work is on the way.

javert · **Posted:** Mon Jan 19, 2009 11:50 am

Ok folks,

There seems to be some interest in learning how to properly check an alternator decoupler pulley. Here's how to do it. Do it both with the engine running and also with the engine off.

Engine running:
1) Note how much movement there is in the belt tensioner. Do this with the A/C on and full alt load. If the tensioner shows excessive movement then the spring inside the decoupler pulley is either broken into pieces or the pulley is locked up.
2) Rev the engine up and then shut it off. Note that the rotor inside the alternator will continue to spin or "Coast" to a stop. Listen for a buzz noise. If you hear a buzz then the bearing inside the alt pulley is worn out and a new alternator decoupler will have to be installed.

Engine Off:
Remove the plastic cap on the front of the decoupler. With a 17mm allen key or a 17x20 spline tool rotate the decoupler shaft while the belt holds the pulley. If should rotate freely in one direction and in the other direction it should have a cushion or spring feel. If it does not feel like this, then you need to replace the pulley. Note: This spring feel is only for the Litens decoupler and not the INA one way clutch pulley. The simple one way clutch pulley will not have a spring feel at all, it will immediatly lock in the drive direction. Note: CRD's came with both the INA one way clutch and the Litens decoupler pulley. These decoupler pulleys are available in the aftermarket at www.iat-usa.com.

Hope this helps,

Javert.

p.s. Maybe the moderator should put this Alternator decoupler trouble shoot procedure in the tech section or make it a sticky. It is good info (that may not even be in the FSM) and there seems to be many people starting to ask about it.

tonycrd · **Posted:** Mon Jan 19, 2009 6:20 pm

I would if your info was a 100% correct, there are CRD's that have the 'splined' version of the decoupler.

So if you add that to your post I would be gratefull if you placed it in the Tech section.

Maybe it's an idea to add the pics we had in the other post of the miller tool etc?

falcn · **Posted:** Tue Jul 02, 2013 11:38 pm

I love the web and this site. Just turned 80k and just developed the seized alternator clutch. I originally thought it was the AC clutch like a lot of people... Then I came on here and found these threads. New 15147 Auto zone alternator later and she is quiet again. No tensioner pulley bounce.

Thanks everyone that contribute to these forums.

AC / pulleys/ serp-belt noise?

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