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Old 12-02-2003, 12:04 PM
Officially Welcomed to the 'Fest
Join Date: Mar 2003
Posts: 23
Mein Auto: 1997 528i
DIY: How to change your belt, thermostat and Waterpump in your 528i

Belt Replacement, Thermostat Replacement, and Waterpump Replacement Instructions for 1997 528i

The procedure below is to be done at your own risk. I have changed the following parts using these procedures with positive results, but may not work for you. The instructions below were performed on a 1997 528i. Other years and models may differ, but I do not know for a fact. I will not be held accountable for any mishaps or accidents. Again, please perform these procedures at your own risk.

Tools needed:

32mm open end wrench
16mm socket
13mm socket
10mm socket
3/8 ratchet
Phillips screwdriver
Flathead screwdriver

Parts needed:

Antiseize grease
Aluminum Thermostat Housing
New Orings for the thermostat and housing (looks kinda square or diamond shaped)
New Thermostat from BMW
New Metal Propellar Waterpump
New Belts (if needed)
New Hoses(if needed)
New screw type hose clamps from kragen, 5/16 size, the smallest size available

Drain the coolant by removing the plastic bolt on the bottom right of the radiator. You will need to remove the bottom plastic cover that covers the whole front of the car (jacking the car up may be needed, be cautious and use jacks stands). Possibly 9-11 phillips screws. <<

Now you need to remove the fan. This fan is attached to the waterpump and needs a little patience to be removed. Use a 32mm open ended wrench to remove the large bolt that the fan is attached to. Keep all belts on at this point. You will remove it clockwise instead of counterclockwise as you would normally remove a bolt. So righty loosey on this one bolt. The bolt is NOT on there very tight. Use a mallet to tap the bolt loose. This may take several taps to get it loose. Once the fan is loose, leave it hanging their because you need to remove the shroud with the fan. After the shroud is loose and dangling, you can either pull the fan with the shroud or wiggle it underneath the shroud(which is what i did).

Removing the shroud: Remove and set aside plastic fan shroud by removing the 2 plastic inserts on top and the cooland resorvoir holder up top. You do not necessarily have to remove the resorvoir completely, just let it sit in the shroud. The fan shroud just slides up and you will need to remove some of the hosing attached below by plastic C clips. Remove the 5/16 hose off of the resorvoir. You can either remove the C clip closests to the resorvoir or the one that is at the nipple. Be careful not to break the nipple part that sticks out of the the radiator. That thing is brittle. Donít worry if you do break it, you can buy it seperately and you do not need to buy a whole radiator like some people have stated in here.

Now the belts. The tensioners are self adjusting, so please review the mechanisms and how it works (see pics below). Remove the accessory belt first (the one connected to the AC). Use a 13mm socket for this one and place it in the picture below. This will release the tension and you can slide the accessory belt off. Now work on the main drive belt. See the picture below for proper instructions. You may not get it at first, but just analyze it and you will get it. There are two holes that you would line up in order to stick something through it to keep tension loose. Use an allen wrench to keep the tension loose while you remove the belt.

Once you slide the belt off, now you have access to the pump and the thermostat. Remove the housing and thermostat first. Make sure you make a note in which way the thermostat goes. When you replace the everything back, it goes in this order:
1. thermostat
2. 2. NEW O ring
3. 3. thermostat Housing.

Now letís move onto the water pump. Remove the 4 10mm bolts that hold the plastic pulley onto the waterpump. Now remove the bolts that hold the water pump to the block. ďGentlyĒ use a flat head screw driver to kind of pry the waterpump out. The reason why you canít really pull it out is because the O ring is set in there. If you did not releive coolant from the block, then a lot of coolant will come out. You have been warned, so have a pan underneath that area. Re-installing the waterpump is straight forward and there shouldnít be any problems there.

That is pretty much it, all you would have to do is replace everything in reverse order. Install new radiator hoses if applicable, Use the NEW generic 5/16 hose clamp from Kragen on the resorvoir hose that goes all the way to the top of the radiator nipple thingy. BTW: use antiseize grease on the bolts.

If you have any questions, email me at

Last edited by GOKOOLJAPAN; 05-11-2005 at 04:20 PM.