Hey all you techies...
The belt under the hood is beginning to squeal in the a.m. when I first fire it up. I live on the west coast where it's foggy in the morning with temps in the mid-50s. It takes a couple of minutes with the engine running before it stops squealing.

In my wife's '92 190-E 2.3 we were told that the belt tensioner unit needed to be replaced ($400!). We were told that the tensioner is an "automatic" one, no adjustments... Am I facing the same thing on my 300E or is there an adjustment that can be done to increase tension on the belt?

T'anks men and women of MB-dom.

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Jay Yambrovich
1989 300 E
1992 190-E 2.3

My 92's belt also squeal in the morning for 1-2 sec.Nothing when warm.Is it belt or the tensioner.
Can I try to replace the belt first and see if it sqeals anymore before replacing the tensioner?

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Tom 1992 300E 2.6

Yes these tensioners have a short life, under 100K mi in normal operation. THe MB pricing is way too high & OE quality aftermarket ones are avail for 1/2 the price.

M.B. DOC -
Is this a procedure that somebody with average to above-average mechanical skills can tackle at home?

I have a fairly extensive assortment of tools and have done a lot of work on my own (non-MBZ) cars in the past (e.g. front strut replacements; water pump replacements; timing belt replacements etc.) so I am reasonably competent as a "wrench" but I DO NOT have a manual for my car. On another posting to this list one respondent said that they were not happy with the MB Service CD-ROM for the W124.

Should I try to do it myself or should I take it in to the shop? What is the "book time" for this procedure?

Thanks for all of your help.

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Jay Yambrovich
1989 300 E
1992 190-E 2.3

Would someone please the procedure for the following:
1) "back off" the tensioner to be able to replace the belt.
2) replace the tensioner - number of bolts/nuts, that type of thing, etc.
thanks
engatwork

OK guys, here we go. For the 300E M103 motor, a number of things have to come off to do a decent job of either replacing or adjusting the tensioner or the belt. The fan shroud must be removed to have access. Two metal clips outboard of the clips that secure the radiator. Pull them off. Work the shroud up over the fan blades. Next, take off the fan blade. 4 metric allen type cap screws hold the fan to the fan clutch. Remove these. Then remove the fan, and shroud. Now you will have access to the tensioner retaining bolt. This is a big fella (19mm). Break it loose about 3-4 turns so it is not applying any pressure to the tensioner hub. Next, the tensioner adjusting screw. Located behind the power steering resevoir. Back this off 'till there is no tension on the belt. There is a little pointer with a scale in the tensioner hub. As you are relaxing the tension on the belt, the pointer should move to the right of the scale. When it reaches the end of the scale, you are OK. Now, remove the belt, making note of the path the belt takes around the pulleys. (it is possible to install it incorrectly). After the belt is off, you will have to remove the bolts from the power steering pump and lay that out of the way. There is a damper (looks like a little shock absorber) mounted on the tensioner hub. This is attached to the pad eye for hoisting the engine. Unbolt this from the pad eye. There is a bracket on the front of the tensioner which is attached to the engine behind the fan pully. Loosen this bolt enough to allow some movement of this bracket. Remove the big center bolt completely, hold the front bracket away from the tensioner hub and work the tensioner assembly out of the car. Reinstall is about the reverse of removal. Remember the little pointer!!. Remove this from the front of the tensioner and place it on the front of the new part. This pointer is adjustable and used to set the tension. Transfer the damper shock to the new tensioner. After installing the new part and replacing all of the hardware you had previously removed, with the exception of the fan and shroud. Put on a NEW belt, properly routing it about all of the pulleys. Do not tighten the big center bolt until you have set the tension. Set the little pointer to the far right end of the scale by gently pushing down on it and moving it a few notches to the right. When the pointer is set, begin taking up on the long tensioner adjusting bolt (behind the power steering resevoir), keep adjusting until the pointer reaches the other end of the scale. Tighten down the big center bolt, reinstall the fan and shroud and go to the corner and buy yourself a big cold frosty. Oh BTW, don't forget to close the hood after you're done...

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Jeff Lawrence
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 07-01-2000).]

Thanks Steve,
I have gotten all the way to removing the fan. Is the procedure that you have outlined pretty much the same for a 1995 E320 model?
thanks again
engatwork

Steve??. I guess I'll take that as a compliment. The procedure is pretty much the same, just more stuff under the hood..

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Jeff Lawrence
1987 300e
1989 300e
1987 BMW 325

The procedure as described seems complicated compared to other cars,specifically GM A cars;like OLds Ciera,Buick Century where you just open hood, turn tensioner/idler counterclockwise and replace belt,question easily done.Replacement in 30 sec.
I guess if you have to remove so many things,may just as well leave it to the MB tech.
The other Mercedes list mentioned that the belt can be replaced without removing anything except the old belt.Can somesone confirm this

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Tom 1992 300E 2.6

Tom go ahead and give it a try. How much skin, knuckles and blood do you want to donate? There are some shortcuts for this task, but a lot of them are very intuitive. I have done it w/o removing anything. Just getting to the center bolt of the tensioner requires a rather deep offset box wrench if you don't remove the shroud. Getting the belt off the pulleys and around the fan and shroud is also an interesting exercise. I described the procedures pretty much the way MBZ describes them. It may take a little longer, but you will be happier with the outcome. IMHO why kill yourself!! I'm sure Donnie can probably do this with one hand and his eyes closed, but we all can't be Donnie. And a lot of us do this for fun and investment in the future of our cars. I for one don't feel the need to mechanically challenge myself anymore than I have to or need to. With the cost of parts these days, to me it makes no sense to jeopardize your investment by trying to beat the clock. Just my $0.02. If one feels that the challenge of this project is inadequate, take on a waterpump removal on this engine. Happy fourth. BTW if you really want a challenge, try changing the front cover seal on one of those tranverse mounted GM I-4's or V-6's.
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Jeff Lawrence
1987 300e
1989 300e
1987 BMW 325



[This message has been edited by jeffsr (edited 07-01-2000).]

Thanks Steve,I am chicken on this one and will leave it to the tax deductible MB tech.

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Tom 1992 300E 2.6

Steve again..WOW twice in one night. Steve if you're out there, please let these guys know that I am not you..

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Jeff Lawrence
1987 300e
1989 300e
1987 BMW 325

sorry about that Jeff. I was thinking of the wrong poster when I thanked you the first time. I have been looking real hard for the adjuster behind the power steering reserviour and have yet to find it. Will keep looking. May go through the exercise just to get down to getting the fan off and if I find everything then will proceed with the change out.
engatwork

The adjuster is a hollow 13mm bolt.(Some have a little plastic cap on the end. Should be at the rear of the tensioner assembly, unless your car (E320) has a different setup.

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Jeff Lawrence
1987 300e
1989 300e
1987 BMW 325

-Remove lower alternator bold.
-Push (or pull) the alternator upward.
-The belt is now loose.
-Remove clips holding the fan shroud and lift shroud to get it free -remove old belt and put new one in

15 minutes work

Don't forget to make a drawing of the routing if you don't have one!!

-if the tension is not right you have to remove the fan and adjust the tensioner

Rob