Alternator Decoupler Clutch Malfunction

WWDiesel · **Posted:** Mon Jan 26, 2015 10:12 pm

Heads up to all! Made a shocking discovery concerning my alternator decoupler clutch yesterday! :shock:

After reading some of the many posts lately on this forum concerning rattling noises at idle and serpentine belt tensioner pulley jumping or twitching excessively at idle. I decided to test my pulley since the tensioner pulley always seemed to jump around a lot at idle and made a little to much noise especially if the AC compressor clutch was engaged.

I had already replaced the serpentine belt tensioner and pulley with a new one from IDParts last year; it helped lower some of the noise, but did not completely stop it nor the tensioner pulley jumping around at idle...

What I discovered was quite surprising; I removed the serpentine belt and then the plastic cover from the end of the coupler and then inserted a bolt with a 17mm head into the hex opening clamped by a large pair of Vice Grip pliers. I then grabbed the pulley with a very large pair of channel lock pliers and tried to turn the coupler in either direction to no avail, it was completely froze up! There was NO red dust or any telltale signs to indicate a problem and it was a new alternator that was installed just prior to my purchase of the vehicle 2 1/2 years ago.

Removed the alternator today and took it to a local alternator shop and they sold me a new decoupler and installed it for free, 45 bucks... Made in the USA too. He also showed my how if you spin the pulley by hand and stop it, the stator in the alternator will keep spinning for a second.

What huge difference it made!!!! Smooth as silk at idle now and no noise or jumping or rattling from the serpentine belt tensioner even with the AC compressor engaged...

Wish I had caught this last year!!!!
Looks can be deceiving... :banghead:

pictures:
Removed pulley:

New pulley:

user113 · **Posted:** Mon Jan 26, 2015 11:54 pm

That's good info. Is there a manufacturer and part number to go along with this replacement clutch?

CATCRD · **Posted:** Tue Jan 27, 2015 12:15 am

Red dust does not indicate failure. Part of normal wear and tear. Functional test like you described is the only real test.

gumbygoose · **Posted:** Tue Jan 27, 2015 2:17 am

I'm pretty sure I'm having this same issue. After my fan fiasco, everything is new. And also have a slight sqeak at idle and a noise when the a/c is engaged. My tensioner also bounces a bit. I'll look into changing this.

WWDiesel · **Posted:** Tue Jan 27, 2015 6:56 am

user113 wrote:

That's good info. Is there a manufacturer and part number to go along with this replacement clutch?

I will call and get the info today from the alternator shop. He did tell me it was the best decoupler on the market, better than OEM. He further stated that it had three bearing instead of the usual one.... I questioned him to make sure it was not some made in China piece of junk especially since the price was so low I was sceptical... :mrgreen:

more later...

papaindigo · **Posted:** Tue Jan 27, 2015 9:00 am

I'd be a bit concerned about the replacement pulley at a price of $45. As I understand it there are 3, not interchangeable pulley types, solid, Overrunning Alternator Pulleys (OAP - also called one way clutch pulley) and Overrunning Alternator Decoupler Pulleys (OAD - also have a one way clutch but also have some internal vibration dampening capacity via a spring). The OEM pulley is a OAD one.

My parts notes say "alternator decoupler pulley 53013554AE or 53013554AF - alternative or Litens 920720 (920834 is a grease filled updated version that is recommeded by Litens, viewtopic.php?f=5&t=78875 , which should fit although it's 2.5mm smaller in diameter) - NOTE some LOST members have reported issues resulting from the installation of inexpensive decoupler pulleys by shops that are not up on the demands of the CRD engine."

Not saying what you got is "bad" just want to get a heads up out there that a solid or OAP pulley is not suitable. FYI the Litens pulley runs ca. $78 at like AutoZone so maybe a shop could have it for less.

Bottom line is a check of your serp belt tensioner from time to time is a good thing to do. Just idle the engine in park, grab a flashlight, shine the light down between the air filter box/fan shroud/engine cover to the tensioner. Essentially no motion is good. This much motion (https://www.youtube.com/watch?v=21zxJMr ... e=youtu.be) or more not good. While the alternator clutch is the most likely source of the vibration/noise problem keep in mind that both the viscous heater and AC compressor have clutched pulleys that might cause a similar problem. Easy to check as you can pull the viscous heater relay to turn it off and setting the dash vent control to "O" turns off the AC compressor (not the AC button as the compressor runs in several vent modes when only heat is on).

dirtmover · **Posted:** Tue Jan 27, 2015 9:24 am

papaindigo wrote:

I'd be a bit concerned about the replacement pulley at a price of $45. As I understand it there are 3, not interchangeable pulley types, solid, Overrunning Alternator Pulleys (OAP - also called one way clutch pulley) and Overrunning Alternator Decoupler Pulleys (OAD - also have a one way clutch but also have some internal vibration dampening capacity via a spring). The OEM pulley is a OAD one.

Sounds like OP went to a shop that specializes in repairing alternators and it sounds like he knows his stuff.

We have an alternator shop in town here and it's surprising how cheaply he sells parts for and also has parts that you can't get elsewhere. His bread and butter is refurbs but he's happy to sell parts with a fair markup to individuals. He's got access to these parts at a much better price than a general parts store, usually in stock and he's probably also marking them up less. They're usually happy to throw in a few minutes of labour with the part as a goodwill gesture.

I wouldn't be too concerned about the $45 price tag. It sounds about right given the source. It's often worth your while seeking out these types of specialized businesses.

papaindigo · **Posted:** Tue Jan 27, 2015 9:48 am

dirtmover - I don't disagree just wanted to get a heads up out there as some have been burned in the somewhat distant past.

WWDiesel · **Posted:** Tue Jan 27, 2015 1:02 pm

I did call and talk to the owner of the alternator repair shop this morning and he assured me the part he sold me is for a Jeep Liberty Diesel. He also stated it fits one other foreign car application. He assured me that it is of the best quality and further told me that only certified alternator rebuilders can purchase this particular brand. Not a Parts Store part!

He showed me yesterday how to test the decoupler functionally by spinning the alternator stator and then stop it by hand very quickly and watch the stator continue to spin for a very, very brief moment.

Higher price does not always mean better. Time will tell if the quality is not there and I will report any problems encountered if they happen… :roll:

I do agree with PAP, Buyer should always beware and question! :wink:

Alternator Decoupler Clutch Malfunction

Who is online