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Old 04-19-2011, 05:14 PM   #1 (permalink)
JA.
BenzWorld Junior Member
 
Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
ML 320 Fan Clutch Repair

Hello All,

I hope everyone is happy and well. I thought I'd share my experiences of repairing the Fan Clutch on both my ML320 trucks: one 1998 build and the other 2000.

In traffic I had started to notice temperatures creeping up and around the 95C mark and thought this was a little too high. On inspection I discovered a couple of issues:
  1. The Fan clutch
  2. The coolant expansion tank (for another thread)

The fan clutch was not operating correctly, one could tell by any number of markers:
  1. The fan would spin for several/many seconds after the engine stopped
  2. The fan could be spun with very little resistance by hand
  3. The fan could be stopped with a rolled up newspaper with the car at operating temperature

A replacement fan clutch assembly form the dealer was several hundred dollars, but there were replacement clutch assmblies on ebay which one could buy quite well around $60-100. Anyway it was a weekend and I wanted to do something about the fan clutch now.

I read the few fan clutch repair threads and webpages that dealt with refilling the fan clutch with new oil. As it turns out (or so the story goes) Toyota had sold some vehicles whose fan clutch had no oil inside them due to a manufacturing fault and so was forced to repair these vehicles, by refilling them with oil at their dealerships. This meant that they had to maintain inventory of the oil. It was a Toyota part 08816-10001 and was a 10,000 CSt oil- silicone oil I believe. So off to the dealership on Saturday I went and paid my $10 for 18 ml of oil.

All the repair threads I've seen deal with removing the copper coloured bimetallic strip on the fan clutch to get access to the tiny actuating piston, which once removed gives you access to a tiny 3mm diameter filling hole.

I attempted this, but found it was difficult to cleanly remove the clips holding on the bimetallic strip and also to heat and cool and also spin the fan in order to drip feed oil in the tiny hole to attempt to fill the fan. I did remove the clips and eventually attempt this method, but is was very slow and to my mind ineffective.

I decided to try something completely different by modifying the fan clutch to provide a filling hole for the oil to make the process FAR simpler and serviceable in the future.

The following posts show this in photos.

Best
JA

Last edited by asianml; 09-28-2012 at 12:48 PM.
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Old 04-19-2011, 05:30 PM   #2 (permalink)
JA.
BenzWorld Junior Member
 
Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
1. Remove the Fan clutch assembly from the car using a 36mm wrench (thanks Dennis for my custom 36mm wrench and lending a hand for this repair) and a long/strong screwdriver. Looking at the engine from the front, turn the fan clutch nut ANTIclockwise whilst using the long screwdriver to stop the water pump pulley from rotating.
Attached Thumbnails
ML 320 Fan Clutch Repair-055.jpg  

Last edited by JA.; 04-19-2011 at 07:01 PM.
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Old 04-19-2011, 05:39 PM   #3 (permalink)
JA.
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Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
2. With the fan clutch asssembly on a flat work surface and held or supported so that it doesn't rock, drill an approx. 4mm hole in fan clutch housing in the position shown. We don't want a ton of swarf inside the fan clutch so drill a little and then blow/vac out the hole as often as possible. For the last part of the hole you could hold the fan upside down with one hand a drill with the other so that any swarf falls out. The wall thickness is probably about 1.5mm in the area. Drilling in this location accesses the main reservoir in the fan clutch. Later we will fit a fine thread metal screw with nylon sealing washer to seal this hole.

The pictures that follow show the bimetallic (copper coloured) strip, clips, actuating piston and sealing grommet removed. THIS IS NOT NECCESSARY. The only reason they are shown removed is that I attempted the repair procedure described earlier - forget it.

Yes I know that that the extra mass of the screw will create a tiny imbalance in the fan, but given the radius of gyration and typical manufacturing tolerances for the moulding and the fan centre I feel that this will not be insignificant.
Attached Thumbnails
ML 320 Fan Clutch Repair-045.jpg  

Last edited by JA.; 04-19-2011 at 06:00 PM.
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Old 04-19-2011, 05:48 PM   #4 (permalink)
JA.
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Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
3. Take a the front of a large syringe and fit it into the drilled hole. I used a 10 cc syringe whose nose fitted AND SEALED the edges the 4mm drilled hole perfectly.
Attached Thumbnails
ML 320 Fan Clutch Repair-046.jpg  
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Old 04-19-2011, 05:53 PM   #5 (permalink)
JA.
BenzWorld Junior Member
 
Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
4. Fill the syringe with the fan clutch oil. It is a 10,000 cSt silicone oil. It is similar in viscocity to honey. Refer to the Toyota part number for the oil in the first post.
Attached Thumbnails
ML 320 Fan Clutch Repair-047.jpg  
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Old 04-19-2011, 06:09 PM   #6 (permalink)
JA.
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Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
5. Fit the plunger to the syringe
Attached Thumbnails
ML 320 Fan Clutch Repair-048.jpg  
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Old 04-19-2011, 06:11 PM   #7 (permalink)
JA.
BenzWorld Junior Member
 
Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
6. Inject all the oil.

Because I removed the bimetallic strip/piston etc I had to cover the centre hole with my finger otherwise the oil would spew out the centre hole. This is not necessary - do not remove the bimetallic srtrip etc..

My fan clutch took all the oil. It may or may not be overfilled, but it seems to work well and is not always jammed ON. If you wanted to be perfect about things you could partly fill the fan clutch and then fit it to the car for trial and refill as necessary. It's up to you. The full 18 ml dose worked for me as the existing oil in the fan clutch was doing very little by way of providing any viscous resistance and the 18ml dose was that required by Toyota to fill their fan clutch.
Attached Thumbnails
ML 320 Fan Clutch Repair-050.jpg  
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Old 04-19-2011, 06:17 PM   #8 (permalink)
JA.
BenzWorld Junior Member
 
Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
7. Find a suitable SHORT fine thread metal screw and nylon sealing washer. You could also use a small flat washer to help press the nylon washer down further, but I used just a nylon washer with a nice broad screw head without any sign of a leak. If you didn't want the hassle of a screw and trying to fit it, you could also use a small piece of metal glued on with Silicone sealant carefully applied around the edges of, but not in the hole. Then wait several hours for curing. I wanted it now, so went for a screw which is also more serviceable.
Attached Thumbnails
ML 320 Fan Clutch Repair-051.jpg  

Last edited by JA.; 04-19-2011 at 06:29 PM.
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Old 04-19-2011, 06:38 PM   #9 (permalink)
JA.
BenzWorld Junior Member
 
Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
8. Fit the screw (the hard part in some ways). Whilst carefully aligning the screw so that it remains perpendicular to the hole screw in the screw using downward pressure allowing it to cut/form its own thread. My fingers are not shown guiding the screw for clarity of pic.
Before attempting this - try this on a piece of thin alumium with the same drill hole. You could of course tap the hole in the normal way if you have the appropriate tap for the screw thread. The fan clutch housing is very thin (some 1.5mm) and even tapping may prove difficult because of the limited clearance below the hole inside the fan clutch. It may not be possible to use an intermediate tap and you may have to use a bottoming tap. Anyway the message is practice first.
Attached Thumbnails
ML 320 Fan Clutch Repair-052.jpg  

Last edited by JA.; 04-19-2011 at 06:51 PM.
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Old 04-19-2011, 06:45 PM   #10 (permalink)
JA.
BenzWorld Junior Member
 
Date registered: May 2010
Vehicle: 98 ML320
Posts: 19
9. Refit the fan clutch to the car and enjoy your new fully serviceable fan clutch assembly. I have read, I think here, that the fan clutch on these vehicles has a life of some 60-65,000 miles/km. So here is a way to save some $ with some DIY and regular refils. The fan clutch no longer runs on for several seconds after the engine is stopped and it does not seems to be creating lots of noise as if it's hard on all the time. Also the temp is nice and cool at around 80C !!!!

Remember - do not remove the bimetallic strip, clips, piston etc. This is unnecessary work for this repair.

Good Luck.

Best
JA
Attached Thumbnails
ML 320 Fan Clutch Repair-054.jpg  

Last edited by JA.; 04-19-2011 at 06:53 PM.
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