strange alterntor or water pump problem
 

car is a 1999 e300td 200,000 miles

2.5 years/45,000 miles ago water pump was replaced- no problems since

2--3 months ago the alternator went out/pulley broke and was replaced with a bosch alternator that appears to be the right part and match the mercedes one

a week ago the fan clutch bolt unscrewed itself and the clutch and fan fell down in front of the radiator
bolt was not broken, scracthed or anything -VERY WEIRD

nothing was hurt, they put the fan clutch back in and 2 days later the bolt backed out again and messed up a bunch of stuff

the new alternator we got was clutched and the consensus was that it needed a none clutched one
there is a lot on the forums about clucthed vs non clutched alternators on this model of car
but i could not come up with a consensus on which one it should have

thinking the alternator was the wrong one i went to mercedes used the vin number and got one there, the parts/shape/numers etc match and the one from mercedes has a clutch also

so we are stumped
they want to put the car back together with loctite on the bolt and see what it does, i still think something is wrong but i dont know what
the replaced alternator seems to be fine, pulley seems fine

but something seems to be stopping/jerking the belt and backing out that bolt


never seen anything like this on any of my cars
any input about alternator issues /pulley issues etc would be great

Clutched definitely. ..
The shop may have mixed up the fan clutch with one from a v8 and it's locking up... the belt may be routed wrong and spinning the fan reverse...

If you go loctite use blue only... NOT RED OR GREEN!!!!

Thanks for the input

I don't think there's anything wrong with the fan clutches because two of them have backed out, and the replacement one was from pelican

I considered the belt being routed wrong also, but I checked it against the diagram in the book and it was fine

This has been by far the craziest deal I have ever had with a car

found the problem
 

the bolt for the water pump seems to screw in correctly and tight but they found that there is a slight wobble when the pump runs

mechanic thinks it was a defect from new, has 45,000 miles on that pump now, so probably just finally wore out from the wobble

not sure of the brand, it was oem though

getting another oem - think graf- hoping this one will be better

if another water pump issue pops up again before 75,000 miles or less think i will just bite the bullet and buy one from the dealer

thanks for the suggestions

I just installed a Graf on the SD and it looked like a well made solid part.

Is this only for the alternator? I used Locktite 271 (Red) on my tensioner a few weeks ago per these instructions.....)

http://www.peachparts.com/shopforum/diesel-discussion/312419-diy-1987-300d-serpentine-belt-tensioner-replacement.html