M104 Fan Pulley Bracket Replacement

[chazola]

On changing my alternator the other day and checking other pulleys with the belt off, I noticed my fan pulley bearing is slightly noisy when spun, and reading some of the horror stories about these failing suddenly and as I'm nearly at 140,000 miles, I'm going to replace it soon.
I'm guessing not, as I haven't seen it mentioned, and haven't had a good look yet- but is there any way of taking the whole assembly (bracket/idler/clutch & pulley) off in one go, since the fan itself is easy to remove... or are some of the bolts for the bracket hidden by the pulley? Seems like it would be easier than taking off the pulley assembly first with the pain in the ar$e that is the locking tool etc...

[Ferdman]

chazola, replacing the fan clutch bearing bracket is quite involved, and requires extensive disassembly of the front of the engine ... at least on our 1991 300CE with the old style belt tensioner. For instance, the power steering pump bolts must be removed and the belt tensioner assembly. Plus, the allen head bolt for the coolant line bracket must be loosened/removed. This is the coolant line to the auxiliary water pump inlet. If the front of your engine is clean the job will be straightforward. I spent considerable time cleaning gunk off so I could see bolt heads.

I bought a reconditioned fan clutch bearing bracket from our local MB dealer, and gave the old one to the dealer to avoid paying the core charge.

[chazola]

Thanks... yeah I have the usual 24 years of gunk on the front of the engine and residue from the infamous front-cover oil leak etc. I just recently did the tensioner so don't really fancy taking it all apart again!

[sixto]

I find a tool that holds the rim of a pulley far easier to use than a pin that slots into the hidden side of a pulley. Seems Harbor Freight doesn't offer one anymore :/



Sixto
83 300SD
98 E320 wagon

[puzzler]

Ive done the water pump and cylinder head r/r for the head gasket and timing cover all with good success but I could NEVER get the slot to hold the pulley alligned or working to hold it, this tool looks awesome! I resorted to clamping the rim with vice grips with some damage..So if anyone has that tool! or knows its source..or a good photo so one could copy the design?? Thanks

[sixto]

There's the MB special tool 603 589 00 40 00 which I imagine is into 3 figures. Looks easy enough to make one since it's not a precision tool.





Sixto
83 300SD
98 E320 wagon

[Ferdman]

Best to loosen pulley bolts while the accessory belt is in place and tensioned, or use a strap wrench on the pulley to restrain it.

[chazola]

Just thought I'd update this now I've finished the job and replaced the fan pulley bracket with a couple of observations for anyone searching in the future:

Answering my own question, the fan/clutch/pulley assembly does have to come off first to access all the bolts for the bracket.
After removing the aux belt I removed the fan from the clutch first (3x 5mm head hex/allen screws), then the idler puller (6mm hex) , then used a strap wrench as suggested here and in other posts to hold the fan pulley to loosen the centre bolt (8mm hex), then the 4x 10mm screws holding the pulley on. It was pretty tight, I had to tap it with a rubber mallet and gently persuade it off with a screwdriver from behind.
Cooling system then had to be drained to remove the heater pipe that runs across the top of the bracket & plugs into the side of the water pump, blocking access to the last bracket bolt, replaced the big O ring whilst there.
Then the easy bit which was old bracket off and new one on, then do it all again in reverse!

I used the Febi bracket, 14946, which fitted perfectly and from reading quite a few posts seemed to fit better than Meyle etc.

The bracket bearing hadn't totally failed, but was noisy with some play and had spewed all it's grease out of the rear seal.

[chazola]

old bracket...

[Ferdman]

chazola, from the picture you can see the old one was a genuine MB part. It will be interesting to see how long the Febi fan clutch bearing bracket lasts, compared to the genuine MB part.

[chazola]

Yeah I've had good luck (so far) with Febi, since most of their stuff is re-boxed anyway, it's usually decent quality- like INA pulleys etc.
I got it for the equivalent of $45 or so on Amazon here in the UK so saved a fair bit on dealer price of an OEM one, if it lasts a good few years I'll be happy!

[benzevo124]

The bearing is shot in my fan bracket and was wondering if anyone ever tried to replace the bearing itself. It looks like a machine shop could easily press out the old one to replace. I don't trust the aftermarket ones for longevity. I taught a good quality bearing have a better chance and cost less than the OEM bracket assembly. I just can't find a replacement bearing by part number on the back side 563510 C.

[97 SL320]

I think I looked at this before and found it was a " water pump bearing " with a single ended shaft. It may be custom for MB so finding it on the open market might not be possible.



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[benzevo124]

You could be right, the shaft seems like it’s part of the bearing. I’ll pull the dust cover off the back of the extra one I have to confirm.


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[Ferdman]

benzevo124, if you need a new fan bearing bracket buy a reconditioned one from your local MB dealer. You will need to turn in the old one or pay a core charge.