Alternator Clutch Pulley

G

GetMeMyStogie

Maple Leaf Marauder Member
Anyone have any part numbers for the alternator clutch pulley?

These things have a few different names:
One-way clutch (OWC)
Overrunning Alternator Pulley (OAP)

There's also the newer style of clutched pulley called:
Alternator Decoupling Pulley (ADP)
Overrunning Alternator Decoupler (OAD), which are like an OAP but with additional harmonics reduction.


So far I've found:

OAP
Dorman: 300-869
(Mitsubishi: A4TJ0181, A4TJ0181ZC)
(Ford: 6W7T-10300-AB)
INA: (F-237401), F-233591

OAD
Gates: 37004P
Goodyear/Continental: 49935
Litens/Tendeco/Atech: 920004
Lester: 11026




() - means I'm not sure

Linked some cross-references, which contains/confirms many of the numbers above.
 
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Replaced my old, seized OAP today, with an OAD.

The original, an INA f233591, fit like this:

1b38f9a27a54841e8ab9da8e7c76d3d5.jpg



ccdad3f5a25ef51b244a4cce1f2c1708.jpg


It's about 1mm away from the case.

The replacement, a Litens 920004 OAD (I ordered the Gates 37004P, and the Litens was in the box) fits like this:

39b34715e08a9635605b7fa3b307cd99.jpg


d399dee1adc4fd5bd2863fbe4ada42d9.jpg


It sits about 3mm-4mm from the case.

Started it up, seems to run fine.

Getting it snugged on with a cordless impact was tricky because letting go of the trigger engaged the electric brake, causing the pulley to spin off a few times due to the inertia of the stator. I ended up using the Auto mode of my Rigid impact, which slows automatically once rotations speed up. If you have an air or plug-in electric impact, that'd work better because then the stator could keep spinning.

Other differences:
- The new pulley is a smaller diameter than the old one.
- The new pulley is installed using a 17mm hex bit (aka H17).
 
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That is not the correct pulley. Yes it fits, but there are over 200 variations of overrunning decoupler pulleys.
 
blazen71 said:
That is not the correct pulley. Yes it fits, but there are over 200 variations of overrunning decoupler pulleys.
Click to expand...

Considering the "correct" part is an OAP, is there any OAD that can be considered correct? You wouldn't happen to have a part number, would you?
 
GetMeMyStogie said:
Considering the "correct" part is an OAP, is there any OAD that can be considered correct? You wouldn't happen to have a part number, would you?
Click to expand...
The Dorman you listed works. I just replaced mine with that one. Your chart lists the Ford P/N in the OAP category and you replaced it with a pulley from the OAD category. Why did you do the research and make that list, and then chose a pulley from the wrong category? Just saying.
 
blazen71 said:
The Dorman you listed works. I just replaced mine with that one. Your chart lists the Ford P/N in the OAP category and you replaced it with a pulley from the OAD category. Why did you do the research and make that list, and then chose a pulley from the wrong category? Just saying.
Click to expand...

Because the OAD was available and about 30% cheaper, and since it's newer tech I'm hoping it lasts longer. Every OAP I've ever used seized up in a year or so.
 
Belt manufacturers tolerance for pulley alignment is 1/2 of 1 rib, so approximately 1.75mm. Your new pulley is way out of alignment tolerance. I would be concerned with throwing a belt.
 
blazen71 said:
Belt manufacturers tolerance for pulley alignment is 1/2 of 1 rib, so approximately 1.75mm. Your new pulley is way out of alignment tolerance. I would be concerned with throwing a belt.
Click to expand...

Thanks! This is actually useful information.

Acording to this, it's 1/2 a rib for every 6 inches of pulley separation. Time to get out a ruler...
 
BTW the belt itself shows some cracking on the ribs. Is that normal/acceptable or an indicator that the belt is approaching the end of it life?
 
GetMeMyStogie said:
Thanks! This is actually useful information.

Acording to this, it's 1/2 a rib for every 6 inches of pulley separation. Time to get out a ruler...
Click to expand...

So I measure about 12 inches on either side between ribbed pulleys. 12 inches between the alternator and power steering pump pulleys. 12 inches from ribbed idler pulley to the alternator, around the smooth idler.

That gives me room for 1 full rib on the belt.

I measured one rib to be about 4 mm wide. And I measured the new pulley to be 5.5 mm from the alternator case. I didn't measure the distance of the old pulley from the case, but 1mm looks close. That makes for an offset of ~4.5 mm. Subtract the width of 1 rib for a difference of ~0.5 mm.

I wouldn't call that way out of tolerance. I'd call it close enough, especially since the "1/2 rib per 6 inches of pulley separation" isn't really a spec, but a rule-of-thumb.

After some spirited driving today, I can tell you there is no belt noise whatsoever. Indeed, there's no pulley noise at all. Where a new OAP would make a whining turbo-like noise when upshifting under WOT, this one is completely silent. While a touch disappointing, I'll keep running it. I have zero worry of the belt jumping.

Btw, this OAD is the part number for 2v 4.6L crown vics and grand marquis.
 
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blazen71 said:
The Dorman you listed works. I just replaced mine with that one. Your chart lists the Ford P/N in the OAP category and you replaced it with a pulley from the OAD category. Why did you do the research and make that list, and then chose a pulley from the wrong category? Just saying.
Click to expand...

The Dorman lists 1998-2005 CV, MGM and MM under applications.

The Litens lists 2003-up CV and MGM under applications.

The overlap tells me the Litens listing is incomplete. I'm not surprised the MM wasn't listed. The fact Dorman lists the same part for these years is good enough for me.
 
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