Hi everyone
I need help putting on the rib belt on 1987 300D. What do you
have to loosen or take off to do this? Thanks to all of you I'm a
wiser MB owner.

1987 300D 252K

There is tension put on the belt with the timing belt tension pulley. There is a allen head bolt that runs through this pulley to hold it in place. You have to first loosen this bolt, then loosen the tension-adjusting bolt that is sticking up next to the power steerring pump. Once this is all loose, then the belt can be replaced. Each car has a distinct way to tighten the belt (based on marks on the tensioner), so you really should look up your specific car in a manual.

GregS

I suppose you can change the belt with the visco clutch on, but it will be a huge PITA. I plan to remove the clutch (as we did on my brother's car -- changed the belt and the belt shock, the shock was bad and the belt worse when we got in there).

To loosen the tensioner, get a long 3/8" extension and put it in the hold in the side of the plastic part the tensioner and belt shock attach too. Loosen the nut on the retainer bolt (top of the head), then push down the the extension (or other prybar) to relieve the tenstion on the spring and push the bolt back. allow the prybar to rise, releasing the spring. Unhook the spring and lay aside, it gets in the way.

The belt goes around the pulleys on the outside, with a loop going up between the crank pulley and the alternator to the tensioner pulley. Only the tensioner pulley runs on the flat side.

You will have to push the tensioner pulley all the way down to get the belt off the other pulleys, then all the way back up to get clearance to get the belt between the crank and alternator pulleys.

If you decide you do need to remove the visco clutch and fan, you will need a shop make tool to get the center bolt out. We used an 8mm allen inserted into a piece of conduit that was hammered down to hold it in place. There is NOT enough room to use a standard 3/8" allen driver, you will damage the radiator. You also need a 3mm allen or a piece of heavy wire to run through the hole in the bearing bracket into the visco clutch to counterhold it. Easy, but fiddly. You will have to use the index finger of both hands to turn the bolt out, you hand won't fit well enough to use one hand.

Installation is the reverse -- install belt, use the bar to re-tension the spring, install bolt, bolt visco clutch and fan back into place.

If the rubber bushing at the bottom of the shock is mushy, replace the shock too.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Huh? Sounds like the belt tensioner for an M103. On an OM603, remove the nut at the top hooking point of the tensioning spring, stick the lug wrench in the tensioner pivot and twist clockwise just enough to relieve tension enough to pull back on the bolt the nut was attached to. Then twist counterclockwise and unhook the spring.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD