Alternator clutch pulley warning

javert · **Posted:** Mon Jan 19, 2009 9:13 am

Folks,

Many people don't know this but you can buy just the decoupler pulley in the aftermarket. There are several companies that sell it, you don't need to go the the dealer and pay big bucks. You can get the decoupler for the CRD from www.iat-usa.com. Call them and order the 39505 part number. They are a company that supplies alternator parts to the rebuilders. The part that they sell is exactly the same as the original equipment. If anyone has any questions about the decoupler don't hesitate to ask them in this forum or PM me. The main difference between a one way clutch pulley and a decoupler is that the decoupler has a torsion spring inside that absorbs vibration within the belt drive system. Another difference is that the decoupler uses a wrap spring type clutch instead of a sprag or roller type like the Ina (as well as others) overrunning pulley. Also, the newest generation of decouplers are grease filled instead of dry clutch type. This means that the protective cap must be installed to prevent grease from flying out of the part. For the record, I am not sure if the CRD has the grease filled type of decouplers yet. The one way clutch type of pulley has only the overrunning function, the Litens decoupler pulley has the overun function as well as the isolation function of the tuned internal spring. If anyone is interested in reading up on this part, there is more information in the "tech tips" section of www.tendeco.com complete with videos as well.

Hope this helps,

Javert

Ranger1 · **Joined:** Mon Oct 17, 2005 7:40 pm **Posts:** 1137

Does anyone build them with a real world, useful life of 100,000 miles? Real world useful life in the context of no noise, no chirping, near silent running? Mine went out at ~40K. This just seems too short an interval with today's materials and precise manufacturing available.

javert · **Posted:** Mon Jan 19, 2009 11:57 am

Ranger1 wrote:

Does anyone build them with a real world, useful like of 100,000 miles? Real world useful in the context of no noise, no chirping, near silent running? Mine went out at ~40K. This just seems too short an interval with today's materials and precise manufacturing available.

The newer ones are grease filled and will last 100,000Kms or more. I don't think the grease filled ones are available for the CRD as of yet, however this may change in the future. The reason why the decoupler wears out so early on the CRD is becasuse of the inherent torsional vibrations (from engine firing pulses) that come from a 4cyl Diesel. In fact this is why the decoupler is needed on the CRD. Without the deocoupler (solid alt pulley installed) you will see the tensioner bounce all over the place and the serpentine belt may even fall off or the tensioner will break. Several other components (idler, waterpump, A/C compressor etc) actually have increased service life because the decoupler is taking all of the abuseive vibration and shock loads out of the belt drive system.

Javert.

gmctd · **Posted:** Mon Jan 19, 2009 12:05 pm

The problem lies not in the sheave, and I've mentioned this several times, previously: a 4cyl has only two violent power-strokes per 360* crank revolution, one per each 180* - 6cyl has 3 per @ 120*, 8cyl has 4 per @ 90* - crank accel\decel torque in each of those is more evenly distributed over the 360* rotation, thus way smoother than the li'l 4cyl shaker - that is why a deteriorated sheave rattles at idle, smoothing out as rpms increase: the averaged forces/time begin to smooth-out as more occur per unit of time - 2thrusts per rotation at 750 revolutions per minute vs 2thrusts per rotation at 1100 revolutions per minute = smooth(er)

'Nuther words, it's idle-time that kills the decoupler mechanism - and if anyone thinks the stinky little 4-banger doesn't need the decoupler (and, you know who you are, eh!), just think how many KJ CRD's are out there, rattling in desperation - including mine!

Not sure if larger sizes are available, but that would be the only solution to try - other than constantly running at fast-idle

Word up, dudes...................

p.s.

BTW - post up the largest 4cyl Diesel engine(s) you've encountered or have heard about, incl VW, Mercedes, Isuzu, Fuso, Mitsu, Hyundai, English\ other Euro, tractors and industrial equipment, incl Cummins 3.9L

javert · **Posted:** Mon Jan 19, 2009 12:48 pm

gmctd wrote:

BTW - post up the largest 4cyl Diesel engine(s) you've encountered or have heard about, incl VW, Mercedes, Isuzu, Fuso, Mitsu, Hyundai, English\ other Euro, tractors and industrial equipment, incl Cummins 3.9L

I know that John Deere uses a 4.5L 4cyl diesel turbo in their big farm tractors.

Javert.

p.s. it also has a decoupler on the alternator to smooth things out for the belt drive.

gmctd · **Posted:** Mon Jan 19, 2009 5:26 pm

I've ridden in the Cummins 3.9L bread trucks and the Mercedes 190D taxis, either of which could be used to settle a bad meal at idle - had massive flywheels to cope with the intense idle-rpm forces - the bread trucks had the GM T400 or the Allison version, where Park was replaced by a granny gear ratio

warp2diesel · **Posted:** Mon Jan 19, 2009 5:31 pm

http://benzinsider.com/2008/03/mercedes ... edes-benz/

I bet this engine vibrated a little.

Google lied, it was a gasser that broke the 200kph speed in 1908.

gmctd · **Posted:** Mon Jan 19, 2009 6:24 pm

Man, I guess it would - I'm trying to illustrate that Diesel engines for passenger vehicles generally cut off at ~2200cc's, 2.2L, just over 120cuin - ours, at 2.8L\173cuin is a relatively huge Diesel requiring dual balance shafts and liquid-filled isolators to calm it down, even in this relatively heavy Jeep - we're up in the industrial\stationary\marine eschelon, but requiring all sorts of magic to reduce those stresses that eat into fuel economy in order to succeed in the emissions-restricted passenger-car category of internal combustion engines - losses to Diesel vibrational distortions are significant, increasing as displacement is increased

tonycrd · **Posted:** Mon Jan 19, 2009 7:01 pm

Dito on that one. Over here anything diesel above 2.5 is a straight 6 or a V6-V8-V10 engine.

JEEP has them but never bothered to fit them in the KJ.... :cry:

Would have been sweet to have the 2.7 or 3.0 of the Grand...wel maybe someday I'll try and see if it fits

Bob V · **Posted:** Tue Jan 20, 2009 12:47 am

I cant get the iat-usa link to work.

honey_don't · **Posted:** Tue Jan 20, 2009 1:10 am

Bob V wrote:

I cant get the iat-usa link to work.

Put "iat-usa" in google and click the first link.

IAT #: 39505
Part: DENSO 6-G LITENS ISOLATOR DECOUPLER PULLEY - JEEP
Category: Pulleys
View picture
Replaces: 021040-1450; Chrysler: 53013554AD, 53013554AE.
Servicing: Denso 117 / 136 Amp. ER/IF Alternators.
Applications: Jeep Liberty 2.8L Diesel.
Alternator #'s: 121000-3850, -3851, -4240, -4520.

Lester #'s: 11114, 13960, 13961.

Dimensions: 43.1 mm L x 17.0 mm Bore x 60.1 mm OD, 6-Groove.

Voltage: 12V

liberty2.8 · **Posted:** Tue Feb 17, 2009 7:56 pm

Any idea on the price of IAT's decoupler?

liberty2.8 · **Posted:** Wed Feb 18, 2009 2:37 pm

Quote:

Any idea on the price of IAT's decoupler?

I called IAT and got a price of 55.85 but I ended up ordering from moparpartsamerica for 56.46 plus got the dust cap for 1.47. Total with shipping was 66.88. I hope I can do this job without the miller special tool because it costs 59.00. Will try the vice method and let you know how it turns out.

ChesterCRD · **Posted:** Wed Feb 18, 2009 2:58 pm

Liberty, If you have an electric impact wrench try that. It worked great for me. I switched directions a couple times and it came right off. The hardest part of the whole job was getting the belt on and off...kind of tight around that fan.

liberty2.8 · **Posted:** Wed Feb 18, 2009 3:27 pm

Quote:

Liberty, If you have an electric impact wrench try that. It worked great for me. I switched directions a couple times and it came right off. The hardest part of the whole job was getting the belt on and off...kind of tight around that fan.

Thanks Chester. I do have a pneumatic impact wrench so maybe it won't be that bad after all.

liberty2.8 · **Posted:** Thu Mar 12, 2009 9:55 am

Ordered and received the new decoupler from Moparpartsamerica last week for $66.88. Used the vice method from an earlier post to get the old one off. New one installed and it's smooooth. Whole job took about an hour. Almost had a major malfunction though. Picking up all the tools after completing the job and getting ready to start her up, something made me take flashlight to make sure belt was all properly lined up. Low and behold, I had forgotten to take the box end wrench loose from the tensioner pulley.Whew, good thing I took a second look. Can you imagine the noise and damage that would have caused if I'd started it with wrench in place.

Just a tip when doing this job...if you're not replacing the belt, DO NOT remove the belt entirely, only take it loose from alternator and keep it tensioned so the rest of belt doesn't come un-snaked from rest of the pulleys. Sure saved a lot of time re-routing belt.

painemann · **Joined:** Sat Dec 20, 2008 7:02 pm **Posts:** 607

KeighJeigh wrote:

ChesterCRD wrote:

KeighJeigh,

Did you experience any symptoms other than noise? I've had a strange intermittent rattle that I haven't been able to localize. It seems to be related to engine speed and is loudest at low speed...like idle. I also noticed recently that occasionally at night when coasting, right before the transmission downshifts, my headlights dim. This is what made me start thinking about the alternator, and this thread got me thinking about whether the occasional noise might be related. Did you experience any of this?

I bet it is indeed the alternator pulley. (I guess the correct term is "decoupler"?)
Yes, I did have slight dimming of the headlights - as if the alternator was not quite as strong as it should be. In hindsight I now know it was because the clutch was starting to slip. Once it completely decoupled last night, it no longer spun the alternator and the lights dimmed dramatically until the engine stalled.
The rattle was most evident at idle and was worst when it was hot outside. Sometimes it seemed barely audible and at other times it was quite loud. The sound was nearly impossible for me to pinpoint even using a listening stick.
Another symptom was the idler pulley bouncing around rather violently. As a comparison, my wife's 06 idler pulley is perfectly steady.

I'd change it before you are stranded as I was.

- Chris

Same symptoms as mine, I ordered and replaced the decoupler and it seems fine so far. I will have to wait for a good hot day seeing as it was the worst with the high temp and AC on.

Thanks for pointing me in the right direction!

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

So I ordered my decoupler and I tracked down a 17mm hex socket for my impact gun now I just need to know how to remove the belt from the decoupler so i can remove the alternator. Can anyone tell me how to remove the belt without it falling off all the other pulleys? Thanks for the help, I need it.

ChesterCRD · **Posted:** Thu Jul 09, 2009 7:22 am

bbertram wrote:

So I ordered my decoupler and I tracked down a 17mm hex socket for my impact gun now I just need to know how to remove the belt from the decoupler so i can remove the alternator. Can anyone tell me how to remove the belt without it falling off all the other pulleys? Thanks for the help, I need it.

Pull back the tensioner and slide the belt off the idle pulley (no lip, smooth pulley). Then release the tensioner. This was plenty to provide the slack I needed to get the alternator out. I think my belt fell off some other pulleys while I was messing around. Make sure you visually verify that it is correctly on all pulleys before you start your engine. Even if it comes completely off, it's really not a big deal to reroute it. There should be a sticker with a picture of the routing in the front of your engine bay.

bbertram · **Joined:** Mon Dec 19, 2005 4:17 pm **Posts:** 144

Thank you, I thought my timing belt was the belt that goes around my pulleys up front so I was scared to remove it. Good to know.

Alternator clutch pulley warning

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