Hello Board,

Great stuff on here and very informative.

Can anyone advise me how to remove/refit the polybelt tensioner on my 1989 year 230TE? I want to replace the damper strut which fits behind and underneath the tensioner unit.

All help gratefully received.

I have not yet had to do one on the M102 but the procedure would be similar to that on an M103 and M104 which I have done.

Loosen the 17mm bolt in the centre of the tensioner and unwind the adjuster until the belt is loose and can be removed. The 17mm bolt can now be removed as well as any other smaller bolts that retain the tensioner. You may need to remove one or more pulleys (eg. steering pump or water pump) to allow access to remove tensioner.

Installation is the reverse procedure. Tension the belt such that the pointer for the indicator moves from one end of the scale to the other.

Since you are removing everything to get to the damper, it may be worth your while to also replace the tensioner itself. They are prone to failure after a period of time, especially when they have been disturbed.

Someone else who has done the job on an M102 may be able to offer more advice. At least yours being in a W124 should allow plenty of space to work.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.

Thanks for your helpful advice.

I'm slightly unclear as to whether the screw adjuster mechanism is an integral part of the belt tensioner, and whether it requires removal along with the body of the tensioner. I would imagine I only have to remove the steering pump pulley, rather than the pump itself, to get at the third retaining bolt.

There's practically nothing in the Haynes manual and the MB CD-Roms don't cover the 2.3 W124.

As I dimly remember when replacing ours, you need to remove the idler pulley, and that may be possible without removing the whole tensioner assembly. Be forewarned, though, that the tensioner function is due to torsion on the rubber cylinder of the the mounting bushing. If yours has never failed before, it is due, from the rubber deteriorating with age. Mine did, and the inconvenience of waiting for the new tensioner with the vehicle disabled convinces me you would be smart to do that now as well.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

Thanks for that.

I'll take advice and replace the whole tensioner mechanism. After 225,000 miles, it's probably prudent.