By: Thomas, R. Malcolm
The definitive guide to under the hood squeaking. This is based on my experience; your mileage may vary.
First off, let me say that in my opinion, your BMW is one tough cookie. Do yourself a favor and do not baby it, it is built to take it.
I have spent the last month (weekends) troubleshooting a nefarious squeaking and squealing coming from the drivers side of the engine bay, it is now gone, here is what I did that works.
1. The "accessory belt" system is complex. Make no mistake, complex, but doable. First off, take a few moments to decide your long term goals of the project. If you are upgrading to major power draining systems, like stero or underdrive pulleys, you may want to upgrade the alternator while you are in there, there is a 120 ~ 140 amp Bosch unit for the E36 M3, it may be what you need.
I recommend replacing (as a minimum) the following parts:
1 each "accessory belt adj. pulley" for hydraulic tensioner. Part # : 11 28 1 748 131
1 each "accessory belt idler pulley" attaches to upper alternator mounting bolt. Part # : 11 28 1 748 130
1 each "hydraulic accessory belt tensioner" looks like a mini-shock absorber. Part # : 11 28 1 717 210
1 each can, H&M Marine Corrosion Block Spray
1 each tube of 3M disk brake, anti squeal goop (red).
You can source them from Pelican Parts (my favorite) or Bavarian Auto or others for that matter.
You will also want to get some RedLine CV joing grease.
Have plenty of paper towels, carbuerator cleaner and / or engine de-greaser on hand too. A can of compressed air would be nice. Not to mention a copy of the Bentley manual (basically wortless) or a photo copy of the belt routing diagram.
This should be a two cup of coffee (if you're a morning person) or a two beer (if you're not) job.
Pop the protective covers off of the two idler pulleys and set them aside.
Release belt tension by sticking an allen wrench in the "accessory belt adjustment pulley" the lower one, and slip the belt out of the way. Now, put a piece of pipe over the allen wrench and crank it in reverse and remove this pulley. Clean the bolt with a bronze brush (better yet, replace it with a nice shiny stainless steel one, my favorite). Discard the pulley after ensuring that the replacement is an exact match.
Remove the upper alternator attaching screw and the attached "accessory belt idler pulley". Clean the bolt with a bronze brush (better yet, replace it with a nice shiny stainless steel one, my favorite). Discard the pulley after ensuring that the replacement is an exact match.
Remove the accessory belt tensioner assembly. It has two attaching bolts, one below the upper alternator attaching bolt at ten o'clock, and one above the power steering pump at ten o'clock. Once the two attaching bolts are removed (Clean the bolts with a bronze brush, better yet, replace it with a nice shiny stainless steel one, my favorite) GENTLY slip a long screwdriver between the aluminum assembly to the rear of the upper attaching point and GENTLY pry it towards the radiator. When it starts to move, remove the screw driver and slip it off by hand.
Remove the "hydraulic accessory belt tensioner" unit and note the orientation. Clean the bolt with a bronze brush (better yet, replace it with a nice shiny stainless steel one, my favorite).
This assembly is an "A" shaped aluminum unit that "floats" on a nicely machined shaft attached to the engine block. The attaching tube has two sets of needle bearings inside (you have GOT TO LOVE german engineering). Remove the front cover washer, clean and set aside. Flush out the needle bearing tube houseing with carbuerator cleaner, dry with a paper towel and LIBERLLY spray with carbuerator cleaner. Make sure all carbuerator cleaner is removed!!!
Clean the entire "A" shaped aluminum unit with engine de-greaser and dry it off. Re-pack the needle bearings and the entire tube with RedLine CV joint grease, apply a liberal dose, it's going to be there for a long, long time.
Attach the new "hydraulic accessory belt tensioner" unit and note the orientation. Add a little "lock tite" to the bolt, you don't want it coming off in this lifetime. Note that the bottom part of the little shock absorber can move left to right, this little tid bit will come in handy later on.
Liberally spray the "A" shaped accessory belt tensioner assembly on the outside with "H&M Marine Corrosion Block Spray", available from many sources. This will keep the aluminum from oxidizing in the future.
Slide the needle bearing housing over the machined dowel and align the lower hydraulic accessory belt tensioner over the attaching point. If you need to, twist it left to right to allign it properly. Put some lock tite on the bolt and tighten to spec. Insert the front washer into the needle bearing housing (to keep the CV joint grease in) and insert the bolt and tighten.
Put some lock tite on the accessory belt adjustment pulley bolt and attach to the lower belt tensioner assembly hole. Put some 3M disk brake anti squeal on the back metal surface of the pulley, wait ten minutes then attach. Tighten.
Wipe the pulley down with a paper towel, chances are, like a greased pig you have CV joint lube all over the place down there.
Put some lock tite on the accessory belt idler pulley bolt and insert in the upper alternator attaching hole. Put some 3M disk brake anti squeal on the back metal surface of the pulley, wait ten minutes then attach. Tighten.
Take a flash light and make sure there is no stray CV joint lube on any of the pulleys.
Take a look for any aluminum oxidation in the engine bay and spray it down with the H&M Marine Corrosion Block Spray, you won't be sorry.
Route the serpentine belt. Double check serpentine belt routing with the Bentley manual.
Start engine and check for noise, should sound like your significant others sewing machine again.
Congratulate yourself on saving the dealers $100.00 / hour labor and inflated parts costs.
IMPORTANT SAFETY TIP...If you decide to swap in a bigger alternator while you are doing this, disconnect the battery F I R S T.....
You will need an air wrench to remove the alternator pulley (a new or re-furbished Bosch will not come with one attached). Chances are you won't be able to remove the pulley from the factory alternator, Hans at the factory makes Lou Farigno look like a pansey.
Hope this helps!
Thomas, R. Malcolm