M103 belt tensioner backwards???

[sixto]

I installed a new belt tensioner and I can't get it to tighten. Here's what I notice:

-- the belt is routed as the old one was and as shown in diagram P20-5140-57 in procedure 20.1133-3120, except that my belt loops around an air pump pulley as well.

-- from the same diagram, it appears that the tensioner idler pulley should tighten counterclockwise relative to the big center bolt.

-- the 'springiness' of the tensioner as I installed it clockwise.

-- When I push down on the tensioning idler, rotating it counterclockwise vs the big center bolt, the indicator moves from the zero position *away* from the tension position; rather, the tensioner moves relative to the indicator.

-- I did not take note of the tensioning bolt during disassembly, but as it stands, it looks just as it should based on the inset diagram P13-5063-13 in diagram P13-5059-57 in procedure 13.1123-3450. Diagram P13-5059-57 shows strut bolt #3 going through the joint in the tensioning bolt. The diagram is unsigned, but it looks to be the work of M.C. Escher.

-- the fact that there's any tension indicates to me that the tensioner is engaged in the tensioning bolt.

I obviously did something wrong, or less likely, have the wrong tensioner.

Can any of you gurus tell what I did wrong?

Thanks,
Sixto
78 450SEL
91 300SE

[jeffsr]

Wow!!! Well to start, the tensioner pully has nothing to do with setting the belt tension, other than applying the "tension" to the belt. There is no adjustment of the pulley bolt.

"When I push down on the tensioning idler, rotating it counterclockwise vs the big center bolt, the indicator moves from the zero position *away* from the tension position; rather, the tensioner moves relative to the indicator."

This sounds normal, as you are pushing the pulley against the tensioner force. The indicator is slaved to the inner sleeve not the outer.

Do this, loosen the big center bolt, back off the adjuster, reseat your belt. Set the pointer to the far right end of the scale. Start to wind down the adjuster, until you get to the far left end of the scale. Tighten the center bolt and button it up. If you can't reach the far end of the scale, the tensioner inner rubber component is either fully or partially detached and the assembly will have to be replaced.. Hope this helps...


------------------
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..

[sixto]

Thanks. Turns out I over analyzed the tensioning bolt; that is, I was turning it the wrong way <blush>. After sleeping on it, I redid the belt just to be sure and caugt my earlier mistake with the tensioning bolt. She's humming now.

I still think the manual diagram was drawn by Escher.

Thanks again,
Sixto
78 450SEL
91 300SE ... next up, motor mounts