Tackling some noise in and around the fanbelt, I found worn bearings in the fanbelt pulley and the guide pulley, which I will be replacing. I also found that my fanbelt tensioner was at the limit of adjustment and also needs replacing.

Checking back thugh my records, I find that this item (124 200 08 70) was replaced in October 2003 by the dealer shortly after I bought the car. Since then the car has covered around 20,000 kms.

Surely this can't be right? I can't believe that a fanbelt tensioner would need replacing that often.

Anyone have any experience with this?

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1987 300e manual 250,000 km (sold)

Hallo Simmo,

On my 1990 W124193 ( 603 turbo ) it's lasting 375000 km now and still in good shape.
In winter at temperatures lower than 0° C, the belt makes some noice.
Than I put some chalk on the inside and the noice is gone.
In your case it's certainly not normal that the tensioner is gone that fast.
Let us know about your sollution when found...
Good luck,

Danny

My 1986 300E was sold in 1993 with 116K miles on it. No pulley/tensioner changes. My 1993 400E has 128K on it. No pulley/tensioner changes.

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Lawrence Coppari

2002 SLK32 AMG
2005 Acura TL
1987 328GTS
1986 944T

You said that it is at the limit of its adjustment. I think you misunderstand how the tensioner marks are used. They are used when tensioning the belt and then do not change until you loosen the bolts again.

When replacing the belt and/or tensioner, you should always do two things; follow the instructions to get it tensioned correctly and spin all pulleys and accessories to check for roughness before putting back together.

BTW, my original tensioner lasted about 200,000 miles.

Good luck,

I would like to know the proceeder for removiing and replacing the cog belt and tensioner on the 6 cylinder 1992 300-E? does nay one have any short cuts to doing this job. Als o what tools do I need?

Thank You
Krwaxbz

You need a 19 mm socket and a 13mm socket. If you are removing the belt for any reason, you need an 8 mm Allen and something to hold the fan clutch (a coat hanger wire for older (pre 89?) models, strap clamp of some sort for later one.

Before removing tension on belt, note the small pointer (usually red plastic I think) that points to the "ramp" cast into the tensioner body. You will need to watch this pointer while loosening the tension.

FIRST loosen the 19 mm center bolt on the tensioner. This bolt holds the center of the tensioner firmly in place, and if you attempt loosen the tensioner with it tight, you will only break the link.

SECOND, while WATCHING the tensioner body, unscrew the 13mm "bolt" that sticks up behind the belt near the head. If the belt comes loose and the markings on the tensioner body DO NOT move back to at least the start of the "ramp", the rubber in the tensioner is shot and it must be replaced. You must watch while loosening, as when you pull the 19mm bolt, the pointer will fall off, it is splined and fits anywhere. It will stay in place if you do not remove the tensioner though.

To remove the tensioner completely you must remove the bracket across the front I think (hard to remember at the moment), maybe not. Some one who's done this more recently will remind me. Tensioner comes right off with the 19mm bolt out.

The bolt that actually rotates the tensioner body is linked to a d-shaped ring that goes on the back of the tensioner body, make sure you know which way it goes back on or it breaks off when you attempt to tension belt.

Going back in, install the ring on the back, put the bolt up through the hold with the round side of the "nut" up, install the pointer so it is at or before the "ramp" mark or where it was when you loosend it (old tensioner), or at the line before the ramp (new tensioner). Snug the 19mm bolt up a bit so the pointer won't fall down, then install the belt (you will have to push the shock over to get the belt on the pulleys), then use the small bolt to pull the tensioner up til the pointer is at the "tall" end of the "ramp" mark. Tighten 19mm bolt.

Not hard, but usually messy from the "normal" front of engine oil leaks.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!