I was driving home yesterday when all of a sudden all the waring lights came on and I lost the power steering.
The engine damn near over heated but I turned on the heater.
When I got home I saw a broken fan belt and the tensioner was loose enough to fall in my hand.
I had seen that the bolt that holds the tensioner to the engine had come loose.
what should I do at this point other than try to reinstall the bolt and a new belt?
I was thinking about cleaning the bolt hole with brake cleaner then putting some red locktite on the bolt and installing it.
Any ideas or comments. Thanks.

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'85 F250 6.9L diesel 2wd XL XC LB Centurion, Gone
'95 Mercedes E 300 Diesel W124.131 with a OM606.910 and just over 200k on the clock, needs top end engine work and a transmission.
2000 S500 W220 with a 5.0L V8 gas power.

The bolt hole opens to the engine so don't put anything in there you don't want to get in the engine oil; worse, in the timing chain.

Check that the tensioner arm bearing turns smoothly - without clicking, grinding or binding - and doesn't wobble. Check the same of the tensioner pulley. Clean the bolt hole surrounding area well and inspect for cracks. You might have dodged a bullet if the front cover is about to come apart.



There's a special MB sealant, not thread locking compound, specified for the bolt. There's an acceptable Loktite brand substitute but I can't remember the name or number of it just now. The bolt takes a seemingly ridiculous 100Nm/73 lbft.

Sixto
87 300D

what do you mean, is it possible the front cover is broken and thats why the bolt came out.

__________________
'85 F250 6.9L diesel 2wd XL XC LB Centurion, Gone
'95 Mercedes E 300 Diesel W124.131 with a OM606.910 and just over 200k on the clock, needs top end engine work and a transmission.
2000 S500 W220 with a 5.0L V8 gas power.

Why wouldnt black or gray rtv work to seal the hole and threads?

__________________
'85 F250 6.9L diesel 2wd XL XC LB Centurion, Gone
'95 Mercedes E 300 Diesel W124.131 with a OM606.910 and just over 200k on the clock, needs top end engine work and a transmission.
2000 S500 W220 with a 5.0L V8 gas power.

Its a cast alum cover.....

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

I guess what I will do is get another washer if I cant find the one that fell out and reinstall everything sing bkeck rtv. If the hole is stripped out or if the cover is cracked i will have to get a replacement.

__________________
'85 F250 6.9L diesel 2wd XL XC LB Centurion, Gone
'95 Mercedes E 300 Diesel W124.131 with a OM606.910 and just over 200k on the clock, needs top end engine work and a transmission.
2000 S500 W220 with a 5.0L V8 gas power.

In the case of the picture, the tensioner arm came of with a chunk of front cover. Obviously not in your case but take the opportunity to check the front cover for cracks. It's very wimpy aluminum to be torquing as tight as a wheel bolt.

Black or gray RTV will work as a sealant but you risk what gets pushed through the hole clumping and falling into the engine. I don't know if that's MB's reason for specifying a particular sealant.

Sixto
87 300D

Check the bolt where it contacts the bushings. It might be worn, the bushings may be worn or shot too. I recall using blue locktite when I installed a new (expensive) bolt.

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2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900

The inside of the alum tensioner body has a sacrificial brass sleeve that rides on the 17mm hex pin. The pin is steel.

The sleeve wears and creates slop/vibration in the assembly

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

I removed the tensioner assembly from the engine since it was already loose and checked the fit with the bolt that holds and everything looks and feels good to me. I think the bolt ma have loosened up on its own somehow.

__________________
'85 F250 6.9L diesel 2wd XL XC LB Centurion, Gone
'95 Mercedes E 300 Diesel W124.131 with a OM606.910 and just over 200k on the clock, needs top end engine work and a transmission.
2000 S500 W220 with a 5.0L V8 gas power.

Is that sealer called gasket eliminator?

__________________
'85 F250 6.9L diesel 2wd XL XC LB Centurion, Gone
'95 Mercedes E 300 Diesel W124.131 with a OM606.910 and just over 200k on the clock, needs top end engine work and a transmission.
2000 S500 W220 with a 5.0L V8 gas power.

The FSM calls it Omnifit 100 M orange sealant which is odd because internet pictures of Omnifit 100 M show a blue bottle.

x2 what connerm said, use blue Loktite.

Sixto
87 300D

Here's the update on my belt tensioner, I got the washer that I thought was lost on the freeway, it was stuck between the block and crank pulley.
The hole for the 17mm bolt is free of cracks and no bad threads.
So I reassembled everything, I put some black rtv on the threads of the bolt for a sealer and tightened it down with a long 1/2 rachet as tight as I could get it.
I got the belt installed and ran the engine for a minute then drove it around the block.

__________________
'85 F250 6.9L diesel 2wd XL XC LB Centurion, Gone
'95 Mercedes E 300 Diesel W124.131 with a OM606.910 and just over 200k on the clock, needs top end engine work and a transmission.
2000 S500 W220 with a 5.0L V8 gas power.