msheehan1@yahoo.com

I have a 1992 300D with about 200K on it. The fan belt has been squealing for about a month now.

Wondering if anyone else has this problem and how it was fixed. So
far the the mechanic say it is the bearing in the fan assembly. He
greased it and it went away for an hour and now it is back.

Cold engine, no noise. 20 minutes later the squealing starts. As you
increase the RPM the noise gets worst.

Suggestions?

Thanks,

Mike Sheehan

Dave M.

Mike, it sounds like the idler pulley for the tensioner assembly. I would at least replace that part. If the tensioner is even the slightest bit cocked at an angle (as viewed from above), it also needs replacement. Or when you loosen the belt and rock the pivot back & forth, if it feels "notchy" (not smooth), it should also be replaced.

Or just go ahead and replace everything including the belt shock. All these items usually don't last more than 100kmi, and most people have the belt shocks fail in less than 50 0r even 25kmi (the rubber eyelets come loose). Aftermarket (OEM) parts are ok for everything except the belt shock... I would specify a dealer (OE) shock, as the aftermarket shocks don't have the updated eyelet design (the change is detailed in the OM602/603 factory service manual).

You'll want item #'s 317 (idler pulley w/bearing), 290 (tensioner lever w/ bearing), and 332 (shock). The plastic caps (314, 326) often break so for a buck each, it wouldn't hurt to pick them up also (they keep crud out of the bearings).

__________________
Dave M.
Boise, ID
1995 E420 - 162kmi (W.I.P.)
1994 E500 - 104kmi (Q-ship)
1992 500E - 162kmi (Mach 5)
1987 300D - 303kmi (Sportline Stage 2)
1987 300D - 247kmi (R.I.P)
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bob_98sr5

when i bought my 87, i had the same problem too. belt was squealing like a pig. rather than waste time trying to figure out what was wrong on my 227k beast, i just replaced all the parts as dave M laid out. even the plastic caps. my cap was missing and i believe thats what hastened the tensioner lever bearing wear. it was full of dirt and there was so much room between the bearings, it was comical.

the trick with this install is removing the fan without removing the radiator. lots of people made a homemade tool (lever) with the right bit attached to it. otherwise, you have to remove the radiator which i did, since i needed to replace the green coolant that the previous owner used (not good)

hboone

Okay, I've replaced the idler pulley twice (you're welcome Rusty) and each time the time-lag before it starts squealing again decreases. I'm convinced that I need to replace the tensioner lever. How do you get the old one off? Do you simply remove the 12mm hex bolt? Mine seems to be extremely tight and I'm hesitant to use more force when I'm not certain.

BTW: It's a 1989 190D with close to 400K used to commute 100 miles a day at @ 35 mpg.