The W126 was offered with at least 5 engine families with distinct accessory drive configurations. The least intuitive configuration is in the M103 family -
PeachPartsWiki: 190E 2.6 Belt Replacement . Here's the main course:
Quote:
To loosen the 19mm nut on the belt tensioner, I used a standard 3/4" (I didn't have the 19mm) socket on a very short extension. I loosened it about 3 turns. Then I loosened up the belt tensioning nut with a 13mm socket. Note - When I was trying to find this nut originally, I couldn't get a good feel for where it was based on the information I found. The good news is that it is a long hollow nut located right above the belt tensioner assembly. It's directed almost straight up. In other words, if you could get your head down into that area, it would probably poke you in the eye! There is a wedge shape cast into the top of the belt tensioner housing in my car. The thickest part of the wedge is on the left and it decreases to the right. The plastic 'pointer' on my car was aiming at the middle of this wedge. I understand that the pointer should move toward the right when loosening tension, but mine didn't move very much. If you pull up on the belt while loosening the tension you can feel the tension ease up (and see the pointer move). Before removing the belt, note the routing of the belt.
My owner's manual included the belt routing diagram:
image
Remove the old belt.
Install the new belt. Back to the tensioner! Manually push the pointer all the way to the right. It may click a few times. Now tighten the 13mm tensioning nut. The pointer should start to work it's way toward the thick part of the wedge. When the pointer gets there, you're done. Now tighten the 19mm nut to lock everything in place. You've finished the belt installation.
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I'll add that if the pointer gets to the thick part of the wedge and the belt is still loose, it's time for a new tensioner. Replacing it is a PITA to describe in words. If you're thinking of a new water pump, do it while the tensioner is out. Man, the M103 is an engine I don't miss working on.
The M103 vies for most ill-conceived but the OM603 takes that honor. I don't know what idiot engineer came up with a tensioner mechanism that can fail and take out the radiator.
Sixto
87 300D
12-24-2013, 10:51 AM
Linear Mode
