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29-05-2014
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AJOR Gold
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Join Date: Aug 2008
Location: Country SA
Age: 66
Posts: 79 What Jeep do I drive?: WH
Likes: 5
Liked 12 Times in 11 Posts
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WH CRD Slow idle causing belt vibration
My serpentine belt vibrates making a rattling noise at idle with the engine cold. The belt, idlers, water pump, tensioner and glow plugs are all new.
The idle speed is about 640 rpm. The vibration goes away when the engine speed is increased to about 670 rpm. I read on a forum somewhere that the idle speed has closed loop control and is supposed to be 760 rpm. (I have not found any reference to this in the Service Manual.)
Does anyone have clues to help restore a smooth idle to my 130,000 km engine?
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29-05-2014
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Irok Bandit
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Join Date: Apr 2012
Location: Wang NSW
Age: 56
Posts: 4,431 What Jeep do I drive?: JT
Likes: 479
Liked 1,189 Times in 788 Posts
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Could be your Alternator pulley
www.youtube.com/watch?v=OR0WEK3JEO4 http://www.ebay.com.au/itm/111136891...84.m1423.l2649
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SOLD 06 Limited G/C QuadraDrive II Lovells 2"Lift +30 rims 265/70/17 Imported Saguaro Bar Stedi
Last edited by Clarky; 29-05-2014 at 09:13 PM.
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30-05-2014
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Lowranger Shocker
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Join Date: Jun 2009
Location: Karratha, WA (Ex Geelong)
Age: 45
Posts: 1,636 What Jeep do I drive?: XH
Likes: 641
Liked 184 Times in 136 Posts
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Yep - Clarky's onto it!
Had the same thing on my wife's KJ CRD and it was the alternator de-coupler pulley. Remove the alternator, soak the thread in WD40 and then use a rattle gun with an internal hex bit to remove. You may need to jam a large screwdriver in to stop the centre from rotating, but it will come. I changed it over and it has been fine ever since.
The violent nature of the diesel power stroke means that the clutch in the pulley wears out over time. To have no clutch pulley though, well you can see the results in Clarky's video.
Good luck!
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30-05-2014
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No Winching
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Join Date: Jun 2010
Posts: 3,145 What Jeep do I drive?: WJ
Likes: 83
Liked 301 Times in 244 Posts
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Another tell tale is a little chirp just as the alternator comes to a stop when you turn the car off.
You can get the proper tool for removing the pulley quite cheaply on eBay if you don't have access to a rattle gun. The drive for the bolt is actually a fine spline not a socket head (hex drive).
If this is the problem don't try buying locally it will cost you hundreds compared to about $80 o/s. I replaced mine in the 2.7, good time to do the internal bearings in the alternator as well. They are common and cheap.
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I got a sweater for Chrissy, nothing wrong with that except I was hoping for a moaner or a screamer.
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30-05-2014
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AJOR Gold
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Join Date: Aug 2008
Location: Country SA
Age: 66
Posts: 79 What Jeep do I drive?: WH
Likes: 5
Liked 12 Times in 11 Posts
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Thanks gents. You are right. I will get onto it. I observed that the inertia of the alternator causes the tension side of the belt to go slack when the crank slows down against compression. I thought it was just a low speed harmonic thing. I didn't know there was a sprag clutch in the pulley, which seemed solid when I changed the belt. It must be seized. Never too old to learn! I hope the sudden accelerations haven't started my armature disintegrating. It probably explains the failure of a friend's alternator at 120,000-odd km. Cheers.
Last edited by Redbaron57; 30-05-2014 at 04:44 PM.
Reason: Grammatical error
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16-06-2014
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AJOR Gold
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Join Date: Aug 2008
Location: Country SA
Age: 66
Posts: 79 What Jeep do I drive?: WH
Likes: 5
Liked 12 Times in 11 Posts
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Last word on this issue: New pulley from US via eBay $80. Set of universal tools for pulley removal $53 via eBay. The WH needed a 30 point spline tool to fit the pulley with a T50 Torx adapter through the middle to turn the alternator shaft. I did the job insitu after removing the engine cover and plastic shield underneath. After cracking the pulley thread, which is not easy as it was very tight, I used a 17mm socket on a strong bar held by a ratchet strap on the shed wall to hold the belt tensioner while I changed the pulley with the belt in place. It took about an hour including some stuffing about. The old pulley was seized solid. With the new pulley the belt rattle at low engine speed is gone and the tensioner no longer pulses violently. I will still remove the alternator to replace brushes and bearings as a precaution since a friends brushes wore-out and destroyed the slip rings. Thanks Clarky, Hanna and fester for your advice.
Last edited by Redbaron57; 16-06-2014 at 05:10 PM.
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16-06-2014
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No Winching
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Join Date: Jun 2010
Posts: 3,145 What Jeep do I drive?: WJ
Likes: 83
Liked 301 Times in 244 Posts
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Cool bananas
__________________
I got a sweater for Chrissy, nothing wrong with that except I was hoping for a moaner or a screamer.
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