need help with belt tensioner and alternator. PLEASE!! - PeachParts Mercedes-Benz Forum

stcbenz83 · #1 12-16-2006, 09:28 PM

ok, so the alternator in the 300 is most likley dead. anyone know how to get the tensioner off so i can get the alternator off? i have the back bolt off but the tensioner thing is keeping it from comming out. its probably really easy, but im at a loss and the haynes manual says nothing about it

thanks!!

Knightrider966 · #2 12-16-2006, 09:33 PM

I don't understand how your belt tensioner is stuck. Mine just unscrews all the way out. Could you elaborate a little more?

stcbenz83 · #3 12-16-2006, 09:40 PM

Two bolts hold alternator on. Regular bolt on bottom removed. Cannot figure out how to remove upper / tensioner bolt. I have un-screwed tensioner all the way (bolt is no longer engaged with tensioner nut) but alternator will not move any further in so that I can slide tensioner bolt up and free of the tensioner nut bracket.

Knightrider966 · #4 12-16-2006, 09:48 PM

It sounds like you have something different than I do! I wish you had a picture to post so I could get a better look at what you got going on. On mine, once the tensioner bolt is removed, there is nothing to hold the bolt back onto the bracket.

Knightrider966 · #5 12-16-2006, 09:50 PM

You may have to remove the entire bracket to get the alternator off. There are only 3 bolts holding the bracket assy to the motor and they should all be removable with the alternator on.

stcbenz83 · #6 12-16-2006, 10:12 PM

here is a picture

JimmyL · #7 12-16-2006, 10:18 PM

Shouldn't it just pull out towards radiator?

stcbenz83 · #8 12-16-2006, 10:40 PM

let me check agian

stcbenz83 · #9 12-16-2006, 11:14 PM

i cant get it to pull out at all

sleeeper · #10 12-16-2006, 11:19 PM

I think you need to actually remove the tensioner bracket- It's been a while bit I think there are 2 bolts above the alternator and the tensioner itself is bolted to the bracket or maybe the block. look for those bolts.

stcbenz83 · #11 12-16-2006, 11:22 PM

i only see one bolt, and then the tensioner bolt. both of which are off

i forgot to mention. THis is a DOUBLE pully system. Im not sure if this makes a differance, but the alternator has 2 pullys on it for the 2 belts that go on it

kerry · #12 12-16-2006, 11:25 PM

It's been a while since I worked on one like that but I seem to recall a bolt that attaches the alternator to the tensioner bolt assembly.

carusle · #13 12-16-2006, 11:29 PM

There are two through bolts that have to be removed, you may miss the bottom one. I think it is a 14 mm socket or wrench that will unscrew the tensioner to loosen it (in your picture). My altenator was a tight fit into the slot in the block, was not easy to move. You may have to force it up to loosen the belt after you remove the two bolts that hold the altenator onto the block. Move it in a way that will loosen the belt. The nut that you see on the tensioner will unscrew and can be removed from the screw. That bolt and the screw that acts as the tensioner is a $35.oo item. Good luck.

vstech · #14 12-16-2006, 11:32 PM

ok, first there are three bolts on the back of the alternator that must be loosened before any alternator adjustment can be made.
second, if you are trying to remove the alternator altogether, you're gonna have to remove a ton of shields and such.
I would start with a cleaning of the area. that is covered in oil, making it hard for you to work on, and hard to see the bolts.
you know you have an antifreeze leak also right?
anyway, one bolt is at the outboard lower position on the alt. one on the other end of the bolt that has the adjuster screw built in. and the third is all the way against the block on the bracket.
John

dmorrison · #15 12-16-2006, 11:33 PM

It is easier to remove the upper adjusting bracket. At the very top of the alternator, from behind is another bolt. This is what holds the alternator adjusting bracket to the engine. Unbolt it an the alternator and upper bracket will come out.
Go here for a diagram from the parts manual. Scroll down.

http://www.peachparts.com/shopforum/showthread.php?t=155908&highlight=alternator+bolts+dave

In the post notice the comments after my post. The Mercedes parts manual shows the bolts "backwards" As so many guys pointed out.

Dave