I have been in the middle of a water pump replacement on my '91 300CE (taking my time over the past several weeks)...

I have everything installed except the new belt - and I can't get it on. I have the right belt and I have it running correctly, just don't have enough length to get it over the last pulley (power steering pump). It doesn't seem like the tensioner is moving enough - to the left (?) I think...

Anyone got any advice? Thanks.

BTW, the tensioner is fairly new - within the last 2 1/2 years and 20K-25K miles...

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Is it the same length as the you that came off?

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Jim

YES. Same Contitech belt with the same 2415 part number stamped on it!

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Is it routed correctly? If yes then it sounds like there is an issue in regards to the position of the tensioner as you already mentioned.

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Jim

Yes. And I know, but what??? I can't figure how how to 'loosen' the tensioner anymore...I must have put it on wrong right from the start...but I don't know what I could have done.

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

i think you will be all right.... get it over the power steering pulley first..... the last pulleys to go over are the alternator. i know it seems like it won't work...but with a screwdriver or some other hardened metal..you can work it over the pulleys on the passenger side of the motor...

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

I tried putting it over the alternator pulley last - still about an inch short...

I was just worried about stretching it too much...I'm not going to bend/stretch something?

It doesn't seem like it should be this difficult...?

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Ryan, do a "Search" under belt tensioner. Perhaps you reinstalled the belt tensioner incorrectly resulting in a limited range of operation. As I'm sure you realize the center bolt isn't fully tightened until the tensioner is set.

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Fred Hoelzle

Well, upon further research it appears that I have the WRONG belt! There are 2 listed based on engine serial number - one is 2415mm and the other is 2445 mm (little over an inch difference). I ordered the 2415 thinking my engine serial # was from 12-042811, which after a call to my local dealer, it is not.

I also looked at the old belt and it clearly has the 6PK 2415 stamped on it! The shop that replaced my idler assembly, shock and belt when I first purchased this car 2 1/2 years ago must have used the wrong belt. Don't know how they got it on...and I'm not sure what - if any - damage might have been caused due to this...

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Ryan, as you discovered there are 2 different length belts available for the 104 engine. Your indy may have loosened the alternator to force the shorter belt to fit.

Installation of the proper length belt is straightforward. Since your old belt was most likely too tight check that all the accessory and idler pulleys turn smoothly indicating their bearings are OK. Perhaps the shorter, over-tightened belt damaged the water pump and tensioner so ensure the tensioner adjustment indicator moves as you tension the new belt. If not, you probably need a new tensioner.

If it were me I would hesitate using the indy again who installed the shorter belt. Screwing up a simple belt replacement smacks of incompetence.

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Fred Hoelzle

Even with the proper belt size, be sure to remove one end of the little shock absorber on the tensioner; that thing is a bear to compress, but extends with no effort at all. It will fight you all the way.

DG

OK, the proper length belt made all the difference - no problem with installation. But, I've got another problem now....

No leaks, which is a good thing, but I've got a knocking noise - related to engine speed - coming from the belt system. I can not find what it is, or where it's coming from for sure...had my stethoscope out probing around - sounds like it's coming from the new water pump - but with the stethoscope on the pump, I don't really hear any knocking. It seems that the only place I really hear a ticking noise through the stethoscope is on the heater bypass pipe that runs right across the front of the motor, right over top of the pulleys.

I don't hear the noise as much at 2500 rpms...

Any thoughts?
Ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

it may be the little shock attached to tensioner ,if it is it needs to be replaced or i slip an oring between rubber sleeve , or a thin washer and knocking will be lessened

I found it! It was - what I think - is the crankshaft sensor. It had gotten bent downward slightly and was hitting against the little timing bump on the crankshaft.

I had a very small drip, drip leak coming off of the starter - most noticeable when I shut the car off - don't see it while the motor is running. Looks like it might have stopped now...I can not find the source though.

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

Good job.

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Jim