Dealing with mangled hardware: 90 300D - PeachParts Mercedes-Benz Forum

ramonajim · #1 10-14-2011, 09:16 PM

Father-in-law type person has a charge light on in his 90 300D (2.5 turbo). Multimeter check plus symptoms suggest it's dead, so I go to pull it off to get it tested to confirm.

Center bolt in the belt tensioner is buggered beyond use. Thinking more working space couldn't hurt, I tried to pull the fan.... one of the three T35 headed bolts is also buggered. Can't get anything close to a grip sufficient to break either free.

Wanting to make sure I get the alternator out, tested, and a replacement set for pick up tomorrow morning, I pull the belt off the idler (took some prying and some swearing). Bench test at Advance confirms both alternator and voltage regulator are dead.

So my cry for help: looking for suggestions for getting the two buggered bolts (belt tensioner and fan) off, and for locating replacements on a Saturday. Guessing the fan bolts I can fake at Napa easily enough, worried about the tensioner bolt.

Suggestions?

ROLLGUY · #2 10-15-2011, 01:06 AM

No need to deal with the center bolt on the tensioner, or "prying and some swearing". Just remove the long bolt going through the plastic part holding the spring for the tensioner. There is a hole in the plastic piece just the right size for a 3/8 drive long extension. Put the extension in the hole, and pull to the left (allowing the long bolt to be removed), and then to the right to relieve the belt tension. Also no need to remove the fan to remove the alternator. You might want to replace the tensioner damper (shock) while it is all apart if it is bad (source of rattling sound, mistaken for the normal Diesel sound).

Junkman · #3 10-15-2011, 10:31 AM

Many times regulator only is bad and not a reason to discard the entire alternator - especially when you're looking at a chain store no-name replacement.

bobodaclown · #4 10-15-2011, 11:11 AM

You might be able to upgrade for cheaper.
http://www.w124performance.com/docs/mb/other/alternators.pdf

aaa · #5 10-15-2011, 11:25 AM

Quote:

Originally Posted by ramonajim

one of the three T35 headed bolts is also buggered.

Is it really a T35? I thought they were plain allens. There's also the big 8mm in the middle of the fan clutch, but you'd have to lock the pulley in place somehow to turn it.

But like someone said you don't need to mess with that to get the belt on and off.

vstech · #6 10-15-2011, 08:50 PM

I've got plenty of parts from my cars to send you whatever you have that's buggered up.
MB did not use any TORX bolts in the engine compartment as far as I know...
most are 5mm 6mm 8mm 10mm etc allen cap screws...
LMK what you need.

ramonajim · #7 10-15-2011, 10:22 PM

Rollguy, thanks for the pointer on relieving the belt tension - somehow got it in my head that it loosening the center bolt was involved.

Darling Wife found a re-man'd alternator through Advance with $20 off + $50 coupon for an online buy. Ordered it last night, piked it up in store this morning. Only snag on the install was that the original alt had bolts holding on the back cover, the new one had studs so I had to acquire nuts.

All systems now good - thanks for the help!