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300GD Cabriolet/G500
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I just noticed the radiator fan pulley in our 98 ML320 is slightly loose/wobbly. When engine running, I can see it causes the belt to deviate slightly back and forth along with movement of the pulley. When stopped, I can move the pulley by hand up to 1/4 inch. Anyone seen this before? Any thoughts on how to remove the radiator fan to check this problem? Thanks in advance for any help.
 

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99ML320 (retired) C230 530xi 911-C4
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slackerguy - 3/28/2005 12:29 PM

I just noticed the radiator fan pulley in our 98 ML320 is slightly loose/wobbly. When engine running, I can see it causes the belt to deviate slightly back and forth along with movement of the pulley. When stopped, I can move the pulley by hand up to 1/4 inch. Anyone seen this before? Any thoughts on how to remove the radiator fan to check this problem? Thanks in advance for any help.
Do a search on harmonic balancer. You might be talking about that....If it is harmonic balancer it is imminent failure and the results are VERY messy. I would stop driving it immediately
 

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Discussion Starter #3
Definitely not the harmonic ballancer--had that replaced 2-3 years ago. Do you know whether the radiator fan pulley should be slightly loose?
 

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1998 ML320
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Here it is 8 years after your post and I am trying to diagnose the same symptoms. Do you recall what the problem was?

Last week my fan belt shredded I suspect because of age. I replaced it and everything looked and sounded fine. 2 days later the new belt started to shred and the fan pulley has a lot of play in it. I put in new belt #2 and the fan now makes a lot of noise and I can see the belt us not tracking straight on the fan pulley, like the fan pulley is wobbling.

I have ruled out the fan clutch.
 

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2004 CLK 240 Coupe
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2 days later the new belt started to shred and the fan pulley has a lot of play in it. I put in new belt #2 and the fan now makes a lot of noise and I can see the belt us not tracking straight on the fan pulley, like the fan pulley is wobbling.
It sounds like the fan pulley bearing has gone. From the WIS drawing, I think that this is a part of the water pump, which would have to be replaced. That takes the fix to another level, unfortunately...
 

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1998 ML320
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Thanks. I kept poking around the site and I also decided it was the water pump. Now the issues of new vs. rebuilt, if rebuilt whose, need special tool to get the fan off, new thermostat, ... At least the temperature is warmer than it has been.
 

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2004 CLK 240 Coupe
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Andy - I don't know if you are a DIY guy. If you are, you should first read through the WIS document below and study all the steps required. I cannot see it in the forum 'stickies'.

The procedure covers several models/engines, so some steps will not be relevant for your W163 with engine 112.942. As you can see, some steps require other drawings, which have not been included here.

Information on torques is shown, and this is important to prevent damaging the threads in the alloy castings.
 

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1998 ML320
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Yes that is it. I took off the pump today (in 30 degree weather). Now I'm waiting for a new pump and thermostat. I am torn but I think I'll change the fan clutch while I'm in there. Its about 150k and has not been changed before. It provides very little resistance as described elsewhere here.
 

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1998 ML320
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1998 ML320
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Pump and thermostat showed up 2 days ago. Got the Graf from Autohausaz. As I read on another post, two of the holes should have been pre-threaded 6 -1.0 but were not. Bought metric tap and die from Harbor Freight and done. I was hoping to get through this without my usual collateral damage drama but no dice. When tightening the bolts I used a ft/lb torque wrench which had a paper conversion chart to nm (newton metre). 2 mistakes - I read the untapped numbers from the MB specs and forgot to convert the number for the 6mm bolts. Doh! I broke off at least one, probably two. finished anyway. No leaks so far. If it does I suspect there may be some stud showing with the pump off so it should be minor drama to get them out.

This vehicle has had a jet turbine like whine, in step with engine RPMs, for years and I thought it was the water pump going. The whine is still there and the idler pulley has a light purr when the belt is off so I'll probably do that next.

Thanks for all the help this site provides. I hadn't considered MB owners to be DIYers. I was wrong.
 
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