Q on steering and A/C belt removal

[VA300SD]

Hello -

The subject is a '81 300D (non-turbo).

I am having to remove the steering pump and A/C compressor drive belts in order to install a new alternator/cooling fan drive belt that wore out and broke. What a royal pain in the butt.

The MB manual discusses only belt tensioning procedure.
(Loosen mounting bolts and adjust the tension with the tensioning screw.)
Does this apply to removal of belts as well ?
(Loosen the mounting bolts and loosen the tensioning screw.)

I am hoping to keep this operation simple and want to make sure I don't perform any unnecessary tasks while taking care of this.
Going ahead and replacing all three belts - they have to be removed anyway.

Thanks for your help !

Alan

Alan,
I don't know if my experience is indicative of the whole breed, but my 1980 300D nonturbo has an incredibly tight a/c compressor belt. I end up cutting it off every time I have ever needed to remove it and bumping the new one on with the started. So far the new belts have never had a problem, but I couldn't get enough slack without removing the a/c compressor and I really didn't want to do that. The steering pump has never been a problem, just back off the tensioning nut enough and you're fine.

someguyfromMaryland

[VA300SD]

Maryland guy -

That is a very simple solution that I hadn't thought of, especially if all three belts are being replaced.

But I don't understand how you got the A/C belt back on if you couldn't loosen up the compressor enough to remove the belt....Did you end up having to partially remove the compressor to hook the belt back on the pulley ?

There must be some sort of standard practice for installing new belts and I am hoping loosening the mounting bolts and tension screw will work on all three belts.

Alan,

When I say bumping the new belt on with the starter, I mean getting the belt on the crank puller and then as much as you can on the ocmpressor pulley, then bumping the starter to make the engine finish the job. It's an old trick and I will state the usual use it at your own risk disclaimer. Any good trick has its drawbacks, I'd hate to see someone lose a finger because they did something stupid like held the belt in place while someone bumped the starter for them.

Loosening the bolts doesn't work on my a/c compressor, and I'm not interested in removing the whole piece to out a belt on. It's up to you.

HTH,

someguy

[VA300SD]

Maryland dude -

Thanks for explaining that.

Yes, a quick burst of starter cranking may work the belt into position.

Thanks for that tip.

And no, not to worry.
I won't do anything stupid.

Take care,

VA300SD

You really should not put any belt on with the starter. You are stressing and possibly even cutting the new belt plus the fact that it is not properly adjusted. Your '81 has an R4 compressor and I agree it is a pain to adjust the A/C belt.

The power steering is loosened/tightened by loosening the bolts that run through the bracket and pump in a fore and aft direction. Once loosened, simply use the long stud and nut adjuster mechanism that extends out of the pump/bracket toward the drivers fender. After tension is correct, retighten the fore/aft bolts.

The A/C is more difficult and it would be much easier if the car is raised a bit. Ramps would work good for this. There are several large bolts that run fore and aft through compressor and it's bracket, and an adjuster that extends toward the drivers side front wheel is available on the compressor as well.

Be patient, take your time and you can replace all three of these belts, tension them correctly and be free of belt problems for many, many miles.

Best of luck,

[be459]

Alan,

For bumping the belts, check this out:

Several Questions about my 1976 300D

David

I read the thread from the above link. Reading it chilled me to my bones. It scares me to death to think of one of our mercedesshop friends holding a screwdriver under a belt while someone elses BUMPS the starter. This engine can very easily start and if it does, who knows what could be the result.

If you can't get any belt off, most likely you have not looked hard enough and long enough to find the necessary bolts or whatever that need attention for this operation. If you can't find them, get some help. I have never seen an MB belt on any device that could not be loosened and tightened with tools. You may find half your wrenches, sockets, extensions, ratchets and breaker bars scattered around the car before you're finished, but it can always be done with persistence.

Please don't take such a risk! If you get stuck on something like this in the Dallas area, let me know and I'll come and try to help before I'll stand by and see someone get hurt.

Be safe and have a great day,

To Larry Bible,

I didn't advocate anyone holding a screwdriver to a belt and bumping the starter. I think everyone is reading too much into my post. I get the belt 90% on and can't get the last bit over the hump no matter what I do. I bump (as in make the starter click, not even an engine revolution) the starter, and the belt is over the hump. In a perfect world, this is probably not the best method. I know it works and I haven't hurt a belt yet. Hope this clears things up. If not, there ya go.

someguyfromMaryland

[be459]

I do not recommend the screw driver trick to anyone. I wrote the message just to answer the question "how this belt was ever put on in the first place!". The belt was the right size but it was still very tight to put in or out. As Steve suggested in the next message, rolling the belt by turning the P/S pulley with the shaft nut or other similar bolts manually is the way to go.

Everyone has his own trick to work around problems. I learned the trick in an Automotive A/C shop when I was working there. We used this method from time to time. We knew what we were doing and took precautions. We knew how much force to put in and at what angle for safety. Instead of using a big screw driver, we also made a tool from a long welding rod for installing and removing belts, very handy. We unbolted the adjustment bolts if necessary during the process. There was no shortcut when it came to belt tension adjustment. As Larry stated, the new belt should be adjusted. The tension of a new belt should be checked 2 weeks after installation also.

David