PeachParts Mercedes-Benz Forum - View Single Post

psfred · #3 03-12-2004, 11:22 PM

Warren:

Hear hear! Why didn't MB use the same tensioner on the M103 and on the OM603? ARgh!!!

Step by step:

1). Buy a new tensioner unless you KNOW the old one is less than four years old. You can test the old one during dissasembly, but if it's bad, you have to replace it and you won't have one.

2). Unclip fan shroud and lay back over fan. If you have a two peice one, just remove the back half and unclip the front and pull out.

3). Take an 8mm allen and a piece of pipe (can't use a ratchet here, dont' try) and insert into the fan bolt. Hold fan clutch by putting either a piece of 1/8" wire bent to about 80 degrees or a 4 mm allen into the "slot" formed by two ridges on the fan bearing and pusing forward to catch a hole in the back of the fan clutch. Loosen bolt, then remove by hand. Tight fit, watch that you don't damage the rad.

4). Note position of the pointer on the tensioner -- should be at the "top" of the ramp mark on the pivot.

5). Loosen the tensioner locking bolt (19mm, I think). You MUST loosen this bolt (goes through the pivot) FIRST, or you will break or twist the tightening screw.

6). Watch the pointer while unscrewing the tensioning screw by the water pump. If the tensioner rotates back to put the pointer at the bottom of the ramp or to the line in front of it, the it's OK. If it only goes part way or doesn't move, the tensioner is bad and you must remove it and replace it. If you attempt to tension a bad tensioner, you will break the swivel on the tightening screw.

7). With tensioner loose, remove belt and install new one. The tensioner shock may push the tensioner pulley all the way "tight" after a few minutes, so if the belt seems WAY too short, just pull on it while pushing the pulley to the "loose"position until you can fit it on. Easiest if you put it on everything but the AC compressor first.

8). Check to make sure the belt is sitting correctly on ALL grooved pulleys -- you may have to get underneath to check the crank pulley, although I didn't.

9). With tensioner bolt just loose, tighten tensioner screw to pull the tensioner up to where the pointer is JUST at the top of the "ramp". Further on a used tensioner, and the rubber tears and the tensioner is toast.

10). If the tensioner is bad (and this is probably why you have belt squeal), it's held on by three or four bolts plus the main bolt. Remove belt, then remove the tensioner retainer bolts, then the main one last. Take the whole assembly off including the tightening screw, making SURE you know how the tightening screw fits onto the flats on the back side of the tensioner -- if you get it wrong going back in, it will break off when you try to tighten. Watch how the pointer fits one, too. You will have to take the tensioner shock off, too.

11). Install in the reverse of removal. Set the pointer to the first line and leave the main bolt slightly loose before putting the belt on. Tension as above.

12). Tighten the tensioner locking bolt. 50 Nm if I remember -- fairly tight.

13). Reinstall fan and clutch (this is fun, the bolt is a pain). Hold clutch with the wire or allen and tighten bolt securely with the 8mm Allena nd pipe extension.

14). Reinstall fan shroud.

Peter