300TD idler pulley damper bolt disappeared

chilsta

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Joined
Jul 18, 2010
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103
Car
'94 S124 E300D
Yesterday I noticed a nasty rattle at idle.

Found that the bolt that holds the idler pulley damper to the tensioning lever had gone, so the shock was swinging loose and pulley was bouncing around.

Today I removed the shock & spring and have rotated the lever enough to get a new bolt in place. (The second photo on iscaboy's post was useful. Was good to see that I could do it without removing the water pump pulley.)
As long as the thread's OK, I think I'll be able to do it without removing anything else (including the fan), although it's going to be tight and will probably involve dropping the bolt down into the engine tray a few times, as is often the way when doing something fiddly like this with cold fingers & minimal room...

My question is, how can I ensure that the replacement bolt doesn't come out again- should I put a spring washer behind the bolt head? Use Locktite on the thread? Or both?
 

BlackC55

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Locktite is your friend.

Don't use too much. Just a droplet is good enough.
 
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chilsta

chilsta

Active Member
Joined
Jul 18, 2010
Messages
103
Car
'94 S124 E300D
So it finally got warm enough (vaguely above freezing) for me to have a try at replacing my wayward bolt this afternoon.

I'd previously tried the M6 bolt that I took out of the top of the damper in the idler pulley lever and it wouldn't go in, so I presumed it must be an M5. However, when trying to put it back together with an M5 bolt I found of the correct length, it just slid straight through. So now I'm thinking it must be an M6 (it would after all make sense to have the same dia bolt on both ends of the damper).
But when I tried screwing in the bolt from the top to see what thread it is it wouldn't go in. The previous bolt has gouged up the hole very slightly when exiting, and it's difficult to see what's going on.
Does anyone know whether the forged hangar/lever is threaded either side of the damper? If so, are they definitely M6? I'm thinking I might have to run a tap into the hole and want to make sure I'm not going to make things worse!
 

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