ML 320 2002 Km 186 000
I REPLACED THE WATER PUMP AT Km 136 000

Part of the waterpump replacement - serpentine belt - automatic tensioner

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Thanks Supradupe for your reply... I start the job tomorrow: ML 320 2002
With a lot of negative ... attitude Why? the " automatic tensioner pulley " or " automatic adjusting tensioner " huge problems - I replaced a new belt last water pump as it shreaded but did I battle!!!!!!

1)These posts help! thanks! but I am a bit slow ..

To remove the belt you need to release the tensioner, to do this attach a torx e10 socket and ratchet to the pully on the tensioner and pull just as if you were loosening up a bolt. There is a hole on the tensioner to hold it in place with a metal rod, I never saw it so I simply slipped the belt off at this point and let the tensioner back out. then slip the belt off toss it and put on the new belt. The tensioner is self tensioning so just let it go and its ready to run. Check to make sure the belt is seated on all the pullys correctly

Question:
A
1) Is this torx bolt on the back of the tensioner pulley (ML 320 2002)? or on the back of the tensioner housing?

2) Can one use a 12" ratchet or a longer breaker bar (or either) with the torx e10 socket?

3) Which direction must one turn or pull the ratchet or breaker bar to release the - Left, Right (while facing the motor)?

4) What degree is the maximum one can turn or pull the ratchet or breaker bar to release ?

5) I think there are casting ***** on the back of the tensioner housing - How does one HOLD the tensioner in place? - long bar, short bar, would the bar run between these ***** and rest against what? or would one shove the bar perpendicular to the *****?

6) Maybe even a pic of the torx e10 socket in place where it goes on the pulley would be nice?

B
Is there another way of loosening the "viscous fan or clutch fan" if one does NOT have the special tool to hold the fan still or steady while undoing the large nut with a flat wrench or spanner?

Thank you

 

Smith007, it's payback time, info for info.
Your pump shaft spring loaded seal is leaking.
The torx screw is on the front in the middle of the tensioning pulley, not much tension there, regular size 3/8 ratchet wrench will do with no problem. Move it counterclockwise (with your right hand) to release the tension from the old belt, take it off at the iddler pulley above water pump (with your left hand) and slowly release the tensioner's spring action. By rotating the tensioner counterclockwise, in certain spot there would be matching hole drilled through pulley arm that you are moving and tensioner base. You could insert steel pin (drill or even allen wrench) through these holes to keep the tensioner arm in "opened" position. But there is no need to do this, ones you done with water pump replacement, place your belt around all pulleys accept upper iddler and now by rotating tensioner counterclockwise, you will gain enough slack to the belt to slip it over the iddler pulley. Side lip of this pulley is small, so minimal tensioner movement is required to move the belt on and off of it.
I have made my own wrenches to do the fan clutch nut (left hand threaded!) I've cut big 3mm flat washer little over half way through, predrilled it with screw patern to fit fan pulley screws and welded to the end of 1/8 thick by 1" wide by 18" long flat stock. Same think I did to make up the wrench but at this time, I just cut the inside of the old wrench in mill to the size of the clutch nut. Good luck!
Bernard

 

Thank you Mbenz80!! The first time - the tensioner %#$@ you don't know the hazzles i went through to get a new belt on. NOW that I know where the 17mm tensioner bolt is - a walk in the park!!!!
I did the job will post pics

PS the ML 320 i have (clutch fan viscous fan) is right handed thread - while facing motor turn nut right (clockwise) to tighten opposite to loosen. There are exceptions according to the specs on some models where they are left hand thread

Thanks Mbenz80

 

One pic so long battling with the rest

If I may suggest one should see if there is play on the water pump pulley every now and again you do not want to damage the aluminium on the block = big bucks!!!!!
Tips: on MY ML320 2002
WARNING (there are exceptions in the wis manual for certain models) on my ML320 2002 Viscous fan or clutch fan while facing the engine turn the nut (with the 36mm wrench) LEFT too loosen

purchase a new water temp sensor as when you go to turn it to the right as there is a little lip on the very top of the water pump that has to clear the sensor when you remove and replace the new water pump

purchase new water pump pulley bolts in the event you damage them when one uses the flat bar tool to hold the pulley in place while loosening the viscousfan nut

On the idler pulley you need a small screw driver to remove the dust cover to get to the internal torx nut thereby allowing you access to the external torx bolt directly to the right of the said pulley

There are 17 bolts to the water pump itself IT IS IMPERATIVE that you take a box like i did map out the NEW water pump like i did and ONE by ONE insert them as you remove

Purchase an idler pulley especially if there is no restocking fee because when the serpentine belt is off and the pulley is spun free ***** it may be pretty noisy especially when you take a 12” piece of wood to your ear and on the centre of the bearing and spin it – change may be apparent
You may have to remove the top radiator hose off the rad side and the bottom rad hose on the rad side so as to easily remove the viscous fan bulky black safety housing which incases the fan

ML320 2002 model:
1) Remove the 2 bolts at the bottom and sides of the viscous fan bulky black safety housing and you may want to slide the housing up as there is a sliding tab on either side of the housing halfway up it
2) Remove the viscous fan

Click on pics