Accessory Belt Tensioner Replacement

[Beerguy5810]

Hi

I have noisy tensioner pulleys that I am told need to be replaced (they're just rough now, but heard stories about how they can come apart). They sound like a can o' loose beebees. Anyway, can anyone tell me if these are easy to install? Can I just follow the DIY tutorial for the belt replacement that is on this site? Are the tensioners easy (and obvious) to get off?

Also, I couldn't locate the tensioners on this website for purchase. Can you direct me to the correct part(s)? I have a 97 528i.

Thanks!

Beerguy

[McCandless]

Not sure whether Pelican sells the tensioners. AND

Without more info on your car, (last 7 of VIN, build date, transmission, US or all others version, etc), I can't be sure to give you the right part numbers. There appear to be two different main belt tensioners for your year.

This site however will let you dig up the BMW part numbers:

http://www.realoem.com/bmw/

I replaced both of mine (US 99 528i A PP)and the deflection roller last year in conjunction with new belts. Time consuming and tight quarters but not rocket science. Make sure you either have a (Bentley or BMW TIS CD) manual or at LEAST draw out the belt routing BEFORE you dis-assemble. And have a good selection of sockets, extensions, adapters, and wrenches! Almost every bolt seemed to need a different combination!

LOL

[Beerguy5810]

Thank you for your guidance on this, and the link. Even with the help, I'm having some trouble correctly identifying the parts.

Here's a diagram...

Seems like I need to replace the pulley (at top) and the tensioner (directly underneath) on my drive belt. Can you help me ID these parts? My s/n is W03310. Thank you for your help

jeff

[Beerguy5810]

Thank you for your guidance on this, and the link. Even with the help, I'm having some trouble correctly identifying the parts.

Here's a diagram...

Seems like I need to replace the pulley (at top) and the tensioner (directly underneath) on my drive belt. Can you help me ID these parts? My s/n is W03310. Thank you for your help

jeff

[McCandless]

Not enough digits in that VIN fragment.
Need the last SEVEN (7)!!!!!!!!!!!!!!!!!
And you CAN find it on the realoem site.
Go there, type in the LAST SEVEN, select engine, and then belt drive.
Find your setup and there you go....
Dunno if Pelican carries these parts but Crevier BMW sure does.

[RANDY P]

the diagram is correct, except replace "camshaft pulley" with water pump and you're there.

In regards to replacing the belts, it's easiest to route the belt all along the top, around the P/S pump and around the tensioner while having an assistant holding the belt against the alternator. In other words, get the routing all done EXCEPT around the crankshaft pulley. Leave the belt loose there - that's the last point when you reinstall the belt

You'll be underneath the car - With your assistant keeping the belt around the alternator on top, pull the tensioner back with your socket wrench and at the same time pull the belt tight with your other hand, right where it goes around the crankshaft and slip it over the pulley.

Wear eye protection - lots of crap comes loose, and make sure your socket wrench has a good hold on the tensioner before you start tugging. You'll be one hand on the wrench, the other wrestling the belt to get it in place.

It's really a 10 minute job once you've gotten the hang of it.

EDIT: -There should be a nub that you can attach a standard metric socket to on the AC belt tensioner - no need for a torx or Hex key. (my 2002 used a torx bit on the upper tensioner - your car might be a hex key)

Good luck.

rjp

[Beerguy5810]

Thank you again for the guidance. S/N is BW03310 (all seven digits this time!). I found a better diagram from a 7-series TIS but seems to represent what I am looking at on my M52. As near as I can tell, the two tensioners (aka pulleys) in the middle need to be replaced. Based on the info above, it seems like at least one of these (the one between the water pump and the alternator) is part Part 11281427252. But I can't identify the one of the opposite side of the water pump. It looks like Pelican only sells the water pump pulley.
Closer look appears I may not have the tools/patience/expertise or combination thereof to replace these myself. Any guidance on how long it would (should) take a mechanic to do it?

Thanks

Beerguy

[RANDY P]

couple hours, and the belts and parts, probably around $300 I estimate. 2 hours, my uneducated guess.

rjp

[McCandless]

With the full seven, looked up the parts. Unfortunately both styles of tensioner assemblies were used. IF! (I SAY IF!) you have the Mechanical Belt Tensioner as mine(build date 11/98) does then 11-28-1-427-252 is the correct number. The upper roller that is held on by a long bolt that also secures the alternator is called a Deflection Roller. Part number for it is 11-28-1-748-130. The tensioner for the Air Conditioner belt is 11-28-1-433-571. And the belts are part numbers 11-28-1-437-475 and 11-28-1-437-450.

On the other hand if you have the other style that kinda looks like a mini shock absorber then you should be able to determine the part numbers you need by spending a bit more time on the realoem site.

Both mechanical tensioners have a (16mm?) hex boss cast into them that you use to release the tension. They also have two small bosses with about a 1/8" hole in them that line up when the tensioner is in the belt tension RELEASED position. All you have to do is release the belt tension with a box end wrench and slip an appropriate sized drill bit shank, small bolt, small screwdriver, whatever, in there to lock the tensioner in the released position. The tensioners are held on with a couple of bolts and as mentioned above, the deflection roller by one large bolt. IMO if you have a fair selection of metric tools and some mechanical ability it's a definite DIY.

Jack/ramp it up enough to get under it comfy and go for it.