I've searched most of the threads and found a lot of information about tightening the serpentine belt on my 1988 300e.

I plan on changing all, belt, pulley, tensioner in the very near future-within a couple of weeks or so.

My tensioner seems to have had it. I loosen the #16 bolt (or 19) all the way, then I turn the nut on my tensioner but nothing happens- either way.

Is there a temporary way in which I can tighten my belt? workaround? or some other means? I like everything I see about the design on my 300e (after growing up with Chevys) in terms of design and repair until I ran into this issue.

thanks a bunch.

I recently replaced the tensioner on my 103 engine . The operation/understanding of the tensioner system is mentioned in detail if you search under "103 belt tensioner ". i believe there are no alternative shortcuts the tensioner and belt have to be replaced .

mak

Yeah, I'd have to agree.
The way it's laid out, I can't really think of a shortcut.
Once you loosen the bolt, loosening belt tension takes a lot of turns. It's a long bolt...
Good luck.
Cam

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1987 300e W124 M103 My baby.

ok. I turned maybe 5 turns either way and didn't notice a change. Will try it again.

Generally, most serpentine belts use a tensioner to maintain tension on the main belt; if it seems loose your tensioner may be weak. The tensioner is usually located near the top of the belt path and has a pulley attached to it. If the belt you are asking about simply drives one accessory, then it most certainly has to have a means of tightening it.

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Art james

Thank you all for the feedback. I'm pretty sure the tensioner is stripped. Turned at least 15 turns and no change on the pointer or in the slack. I put a tiny bit of belt dressing and that seems to have taken the shrieking noise away.

Will look for the parts and probably do a change over. I do understand the difference between the american alternator belt's simplicity in design and maintenance (being able to adjust it by swiveling the alternator), but then again, you gain vibration.

On the 300e, this might be the reason why the engine is so smooth and efficient balancing of torque. Ridiculously smooth- but what a pain to correct.

Make sure the 19mm bolt in the tensioner itself is loosened before you try to adjust the tensioner bolt. Not doing this could either strip the adjuster threads or see below. The adjuster is reverse thread. If there is no adjustment happening then the tensioner will be toast - a M103 weak point. Don't start messing with the alternator - you can damage the bearing in it. Change the tensioner. - It's a PITA to change but straight forward.

a chirping belt due to a weak tensioner effects the alternator operation though it may not be apparent. replacing the belt & tensioner and the engine will run very smooth as the slippage a at the power steering altenator and a/c pulley ceases.
mak

Well thank you all. You were all correct. No simple fix. I bought the tensioner/belt/shock and got down to business.
Started Friday night and finished Saturday morning. There is one particular bolt that is troublesome. One of the small 8mm that holds the left most part of the 'y' bracket-near the timing chain.

Turns out I didn't have to remove it, you can swing the 'Y' bracket slightly and the tensioner loosens and drops down.

Make sure to check your shock- at the time it's easy access anyway.

Did find a decent way to hold the pulleys down. Take the old serpentine belt you just took off, cut small 3" sections and place 1 or 2 on 'belt' side of the pulleys, and one other piece on the inside lip of the pulley. Clamp down on it with a vice-grip, and turn the pulley until you can lock it against the engine block or the power steering pump.

At that point, it doesn't take a lot of torque because it locks in place- no slipping.

Thank you all for your help. Saved me some $hundreds on the quote from the local Benz shop. Can't imagine what the dealer would have quoted me.

Happy Holidays to you all.