AC squeal

dgeist · **Posted:** Thu Jul 24, 2014 4:18 pm

So, I was able to finally get some tools to troubleshoot the OAD on the alternator. It spins freely (well, with a little force to move the stator) in the clockwise direction and has the "springy feel" in the counterclockwise. There is some gray dust under the cap, but by no means a large amount. I'm starting the suspect the tensioner is the culprit for my noise. I hate to replace a perfectly good OAD for no reason... Has anyone else their tensioner go south and can you describe the noise? I'm at about 110k miles on the original tensioner (<1yr old belt, though) and it's supposedly a wear item, but I don't know the change interval.

Dan

crdblazr · **Posted:** Sun Jul 27, 2014 4:05 pm

After moving to Dallas, TX and running the AC nonstop in the summer of 2012, I started getting a noise when turning the AC on. For me it was a loud rattling noise, not a squeal. By November 2012, it had worsened to the point where I finally took the Jeep CRD into a local shop for repair. The mechanic's diagnosis at that time was a bad serpentine belt and tensioner, so I got those replaced.

Then four months later, in March 2013, the noise started to return and I had to replace the alternator. After reading the postings here, I realize that the failing alternator (specifically the decoupler pully) is most likely what caused the failed tensioner in the first place.

The problem has now returned. I remember now that earlier in the spring, I noticed a minor chirping noise when at idle but I didn't think too much of it at the time. However, last Thursday, I heard the same loud noise again with the AC on. My Jeep CRD is at the shop now and the mechanic once again says the tensioner needs to be replaced. With the fan assembly off, they showed me how the tensioner pulley was bouncing around unnaturally. It really was all over the place. They also showed me with a wrench, how little resistance the tensioner spring was providing.

I'd like to avoid going through this all over again... replace tensioner, then back to shop for another alternator or possibly replacement of a different component this time (compressor?).

Does this sound the symptoms of a failed tensioner? Is there any guidance I should give the mechanic to troubleshoot the root cause of the problem? This is a decent shop but mine is the only Jeep CRD they've worked on.

I'm also wondering if going forward, I need to just plan on replacing the tensioner every two years... the first one lasted a little over 6 years but this will be my second since 2012.

papaindigo · **Posted:** Sun Jul 27, 2014 4:29 pm

IMHO you have a bad alternator pulley and the tensioner is just fine. The spring tension on the tensioner is not particular high; modest resistance to be "untensioned" at most. Wish I could give you a torque figure but cannot. I'm assuming what they showed you with the fan assembly off was that with the engine running the tensioner was bouncing a lot not the normal barely twitching. That's a classic symptom of a failed alternator pulley which can if left unattended destroy a tensioner usually by breaking the spring which can cause the tensioner to lean into the power steering pulley.

I see you replaced your alternator. What brand was the replacement? It's critical that the replacement use a quality (Litens or OEM) pulley not cheap knockoff or worse yet a pulley that's not a decoupler one.

crdblazr · **Posted:** Sun Jul 27, 2014 5:04 pm

papaindigo - thanks for your reply. I'm not sure of the brand of the reman alternator installed in March 2013, but I will call the shop tomorrow to pursue replacement of the alternator decoupler pulley as a first step rather than replacing the tensioner. If the tensioner is too far gone, maybe I will need to do both. However, it did not appear to me that the tensioner spring was broken.

dgeist wrote:

This thread has been pretty informative:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=78875

I just reviewed the thread above and it is indeed very informative. If possible, I'd sure like to put the improved Litens OAD pulley (PN 920834) on there for longevity reasons. Hopefully the Litens part is available somewhere locally, as we don't have Advanced Auto in the Dallas area.

dgeist · **Posted:** Sun Jul 27, 2014 5:19 pm

crdblazr, I came to the same conclusions, but ordered a new tensioner and got some replacement bearings for the other guide pulleys as well. They're original, so they need replacing anyway. Hopefully, the Litens OAD I bought will not be needed right away...

Dan

striperman36 · **Posted:** Tue Jul 29, 2014 10:35 pm

what socket do you use in adding to the 17 mm hex driver?

Replacing mine tomorrow, I hope

crdblazr · **Posted:** Tue Jul 29, 2014 10:43 pm

I was able to find the upgraded Litens OAD (PN 920834) at a local Jeep dealer and my mechanic installed it on my alternator today. This fix has resolved the loud noise when turning on the AC and the horribly bouncing drive belt tensioner.

I posted additional details about Mopar part numbers in this other thread: viewtopic.php?f=5&t=78875

Auberon · **Posted:** Wed Jul 30, 2014 11:28 am

x 2 the last post by papaindigo.
It's good to read some of these issues are being sorted out.

I do just love the way those with a vested interest like the Gates Corp etc say replace the tensioner and the OAD and the belt and the idlers all at the same time. OK, in an ideal world....... but how many parts that are still totally serviceable are we throwing away if we follow that practice. Its like that becomes as big as a timing belt job. That adds up to a lot of dollars I'd rather have in my pocket. Sheesh!
My own policy is this:
OAD is the 1st culprit and I also do the accessory belt at the same time as you can pick up a Goodyear belt and a Goodyear OAD on close-outs for USD100. I also do the acc belt if I do the timing belt at any time.
With regular belt and OAD replacement the whole thing seems to keep on trucking reliably and smoothly.
Any belt bounce AT ALL and I start to look for the cause.
It should always be smooth and sweet running gear with no hint of bounce or jounce in any direction.

If it helps any - I'm a big fan of Gatorbacks for timing and accessory belts. These belts are the bees knees.
I like the Goodyear as they're either Canadian or US made.
My Timing belt was done at 50 000 km (6 1/2 year) with a Gatorback and was arrived even dated for month and year of manufacture so I new it hadn't sat on the shelf in a storeroom for eons. That is a mark of quality.
The bearings for the idlers I always have on my work shop shelves as they fit too many other things I run and just replace bearing only.

Many of our extraneous components are running so slowly compared to the petrol/gasser engines - Fuel pump is 1:1 drive with the crankshaft, alternator is not too fast either.
None of this is fast nor heavily loaded nor shock loaded by the diesel as long as the drive is kept free of shock loads by a smoothly running belt and OAD. If this is avoided then the tensioner should hardly ever fail.

In petrol engines I usually get 200 000 miles out of tensioners before replacing as a precaution and ours do a lot of idling in heavy stop-go traffic.

dgeist · **Posted:** Sun Aug 10, 2014 10:49 am

Wonder of wonders...all my accessory noises stopped (while I was assembling all the parts to fix the pulleys, tensioner, and OAD). Apparently, it either goes completely silent right before it's about to explode or I got something in there somewhere that made one of the pulleys chatter for a matter of weeks, but finally worked its way out. Regardless, I have all the parts to replace it if the accessory drive system decides to implode some day.

Anyone else just had problems in this area mysteriously stop?

Dan

diesel_guy86 · **Posted:** Sun Aug 10, 2014 1:15 pm

Does anyone know what bearings to get to replace the stock ones? I'd like to keep a small parts stash of stuff like this so when it happens to me I'll be ready.
If someone could condense all the part #s for things like:

The alternator decoupler,
The tool kit for the decoupler,
Bearings for idlers,

It'd be a nice lil cheat post for anyone having these problems, as they seem to be happening more frequently.

dgeist · **Posted:** Sun Aug 10, 2014 2:59 pm

diesel_guy86 wrote:

Does anyone know what bearings to get to replace the stock ones?

These are used in the idler and tensioner pulleys. Make sure you get the "FF" type or it'll only have grease seals on one side.

Dan

AC squeal

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