My belt got coolant on it and has squealed for 3 months. Belt dressing helped for a short while. I want to change the belt . I cannot find a thread that tells me step by step how to do it- I thought I saw one awhile ago.
Please tell me how or help find the thread. Our tech session is tomorrow!
How to check tensioner/would belt dressing help if tensioner bad? I think tensioner is fairly new.

Do a search o M103 and water pump.

You have to loosen the tensioner, remove the fan blades and the belt will come out. Retension the belt, put the fan blades back on and viola.

IMHO, this is a dumb design. The tensioner should be spring loaded and the belt removable without disassembling anything else.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

Warren:

Hear hear! Why didn't MB use the same tensioner on the M103 and on the OM603? ARgh!!!

Step by step:

1). Buy a new tensioner unless you KNOW the old one is less than four years old. You can test the old one during dissasembly, but if it's bad, you have to replace it and you won't have one.

2). Unclip fan shroud and lay back over fan. If you have a two peice one, just remove the back half and unclip the front and pull out.

3). Take an 8mm allen and a piece of pipe (can't use a ratchet here, dont' try) and insert into the fan bolt. Hold fan clutch by putting either a piece of 1/8" wire bent to about 80 degrees or a 4 mm allen into the "slot" formed by two ridges on the fan bearing and pusing forward to catch a hole in the back of the fan clutch. Loosen bolt, then remove by hand. Tight fit, watch that you don't damage the rad.

4). Note position of the pointer on the tensioner -- should be at the "top" of the ramp mark on the pivot.

5). Loosen the tensioner locking bolt (19mm, I think). You MUST loosen this bolt (goes through the pivot) FIRST, or you will break or twist the tightening screw.

6). Watch the pointer while unscrewing the tensioning screw by the water pump. If the tensioner rotates back to put the pointer at the bottom of the ramp or to the line in front of it, the it's OK. If it only goes part way or doesn't move, the tensioner is bad and you must remove it and replace it. If you attempt to tension a bad tensioner, you will break the swivel on the tightening screw.

7). With tensioner loose, remove belt and install new one. The tensioner shock may push the tensioner pulley all the way "tight" after a few minutes, so if the belt seems WAY too short, just pull on it while pushing the pulley to the "loose"position until you can fit it on. Easiest if you put it on everything but the AC compressor first.

8). Check to make sure the belt is sitting correctly on ALL grooved pulleys -- you may have to get underneath to check the crank pulley, although I didn't.

9). With tensioner bolt just loose, tighten tensioner screw to pull the tensioner up to where the pointer is JUST at the top of the "ramp". Further on a used tensioner, and the rubber tears and the tensioner is toast.

10). If the tensioner is bad (and this is probably why you have belt squeal), it's held on by three or four bolts plus the main bolt. Remove belt, then remove the tensioner retainer bolts, then the main one last. Take the whole assembly off including the tightening screw, making SURE you know how the tightening screw fits onto the flats on the back side of the tensioner -- if you get it wrong going back in, it will break off when you try to tighten. Watch how the pointer fits one, too. You will have to take the tensioner shock off, too.

11). Install in the reverse of removal. Set the pointer to the first line and leave the main bolt slightly loose before putting the belt on. Tension as above.

12). Tighten the tensioner locking bolt. 50 Nm if I remember -- fairly tight.

13). Reinstall fan and clutch (this is fun, the bolt is a pain). Hold clutch with the wire or allen and tighten bolt securely with the 8mm Allena nd pipe extension.

14). Reinstall fan shroud.

Peter

__________________
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!

Excellent directions Peter. I think I need a new tensioner. I'll get the little shock too.

I had trouble getting my fan pulley off so I just worked around it, during my water pump ordeal. (it was cold in January)

The weather is getting warmerm the water pump is not leaking and the car is running well.

I need ball joints though, it pops a little now and then.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

FYI for the fan clutch, MB sells a special short 8mm socket to fit 3/8" ratchets. It's just a touch short of an inch long, and while I haven't yet tried mine, should work with most ratchets/torque wrenches with some room to spare.

The part number is 103 589 01 09 00, about $10 through parts shop.

Thanks everyone for the good advice. I went to the tech session and the MB guy said the noise came from the pulley on the tensioner-not the belt. Confusing as the previous session guy sprayed belt dressing on the belt and the noise went away. During this session we pulled the plastic cover off the pulley bearing and sprayed with wd40-less noise! (unless we got overspray on the belt.) Will have to do some more work.

For tracing down noise up front, there is nothing like a stethoscope.

Only $4.99 at Harbor Freight.

I've always heard/read to avoid using belt dressing which is a quick and dirty cure for slipping drive belts because it hides the real source of the problem ... inadequate tension or worn belt. It really surprises me that a well trained MB tech would resort to belt dressing, particularly in a Tech Session where you should learn simple diagnostic techniques and DIY repair.

__________________
Fred Hoelzle

Belt dressing will remove glycol, and that is an acceptable use, but otherwise, if the belt squeals, softening it up temporarily is indeed a temporary fix, and will leave you without the belt sometime soon.

Serpentine belts very rarely squeal anyway -- they will run quietly in pretty terrible shape for a long time, the suddenly fly off when enough cording is broken so long as they are tight. Don't even squeal much when they are loose -- my brother heard a funny whistle from my 300D last years when he borrowed it while driving with the window down and smoking (the main reason I hate to lend him my cars!) -- the tensioner spring was MISSING and the AC still worked!

Squeals are usually a bad tensioner or a bad idler bearing -- they can whistle and growl, too.

Peter

__________________
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!

Thanks everyone
psfred-good instructions now that I saw how to do it. My apparent problem was early water pump decline(rough when turning the shaft) and another pulley was bent and not tightened properly. After both replaced the belt still squeaked slightly so I replaced it also with good result( told it was a bit "dry".)
I think most of the techs used belt dressing more as a diagnostic aid. My opinion is that the belt slipped for other reasons than just being dry.
Also my tensioner does not have the marks on it like shown in the shop manuals-aftermarket or a label that fell off?

The marks were cast into the new tensioner I got -- they may have been on a sticker on the original.

Not the best design around...

Peter

__________________
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!