E36 Cooling System Overhaul Notes

I recently purchased a new-to-me '97 328is from VA, and it was overdue for a cooling system overhaul. When I bought it, I received the complete maintenance records from the second owner, who bought it as a CPO and had it for about 10 years. When going through the receipts I didn't see anything about the water pump being replaced, so that was added to my list of to-do items. Luckily, I had an OEM pump with the metal impeller, so it actually lasted the 114K just fine. I figured that while I was at it I would replace the belts (last replaced at 50K), radiator (original), and thermostat housing (wanted an aluminum one instead of the OEM plastic version). The fan, fan clutch, and expansion tank seemed to be in good shape so I kept the originals, but I did replace both upper and lower radiator hoses. The cooling system was working fine when I bought the car, but I wanted to buy a few years time of reliability. Water pump failures on these cars often come without warning, and I didn't want to be dealing with a potential overheating/head gasket because I was too lazy to replace the water pump.

I ordered the parts from Bimmerzone (through the BimmerForums.com website), and was very pleased with the transaction. The prices were very reasonable, everything was well-packed, and it arrived quickly. I'd definitely do business with them again. Removal phase: -

• Confirm you have the radio code, remove negative battery cable

• Removed radiator cover (4 Phillips screws), airbox (two 10mm nuts), and alternator ram air ducting (6mm hose clamp)

• Remove aux fan temp sensor (plugs into radiator)

• Drained (Phillips head screw) & removed radiator -I had bought a new one to replace it - If you're replacing the radiator, move the two rubber "feet" from the old radiator and put them on the new one

• Drained engine block of coolant 19mm drain plug head (had to remove and reinstall O2 sensor that was right in the way of the block drain plug, covered O2 sensor hole with duct tape while the coolant was draining)

• Removed upper and lower radiator hoses - 6mm hose clamps

• Removed primary fan using 32mm open-ended wrench and pulley holder tool

• Detached fan shroud (2 rivets)

• Removed expansion tank by unclipping coolant level sensor and removing the two hose clamps that attach to the expansion tank

• Removed water pump pulley - four 10mm bolts

• Removed water pump - four 10mm nuts, used two 3" long M6 bolts to back out the water pump

• Removed thermostat housing and thermostat (three 10mm bolts, one 13mm bolt that secures the engine lift hook) Install phase:

• Water pump (four 10mm nuts)

• T-stat and housing (3 10mm bolts, 2 13mm bolts for engine lift hook - longer bolt goes on the top). I installed an aluminum housing, so I used thermostat/water pump RTV along the outside edge. The instructions said it would be fully cured within 24 hours, so I waited that amount of time before adding any coolant

• Radiator, and aux fan temp sensor (plugs into radiator) - remember to get the rubber bumpers off of the old radiator

• Lower hose to expansion tank (hose runs along bottom of the fan shroud to the engine block) - 6mm hose clamp

• Upper hose to expansion tank (hose runs along the upper part of the fan shroud to the driver's side) - 6mm clamp

• Install belts (water pump/alternator first, then A/C belt) 16mm on alternator/water pump tensioner, 8mm Allen key on A/C tensioner

• Rotate fan shroud out of the way with expansion tank installed

• Lower radiator hose - 6mm hose clamp

• Plug in coolant sensor

• Rotate fan shroud back down and install 2 fan shroud rivets

• Install fan (32mm open end wrench)

• Install upper radiator hose - 6mm hose clamp

• Connect upper expansion tank hose to radiator on driver's side - 6mm hose clamp

• Replace plastic cover and alternator ram air ducting - 6mm hose clamp

• Replace airbox (two 10mm nuts)

For bleeding the system, I basically followed the Bentley manual:

• 50/50 mix of BMW coolant (blue) and distilled water (found in cleaning supply aisle)

• Front end up on ramps

• Ignition on, engine off

• Reservoir tank open, bleeder screw out

• Cranked up the heater controls to max warm (90 degrees) on the lowest fan setting

• Slowly added coolant until it no longer bubbled out the bleeder valve

• Reinstalled reservoir cap and bleeder screw

• Ran up to full operating temp (kept revs between 1-1.5K RPM)

• Let idle at full operating temp (gauge stayed in the mid-range)

• Shut down engine

• Once engine was cool, rechecked the level and added as necessary

Here are some pics with notes: http://s672.photobucket.com/albums/vv82/dj06482/E36/E36%20Cooling%20System/

Tim - help on the formatting!

dj06482 wrote: I recently purchased a new-to-me '97 328is from VA, and it was overdue for a cooling system overhaul. When I bought it, I received the complete maintenance records from the second owner, who bought it as a CPO and had it for about 10 years. When going through the receipts I didn't see anything about the water pump being replaced, so that was added to my list of to-do items. Luckily, I had an OEM pump with the metal impeller, so it actually lasted the 114K just fine. I figured that while I was at it I would replace the belts (last replaced at 50K), radiator (original), and thermostat housing (wanted an aluminum one instead of the OEM plastic version). The fan, fan clutch, and expansion tank seemed to be in good shape so I kept the originals, but I did replace both upper and lower radiator hoses. The cooling system was working fine when I bought the car, but I wanted to buy a few years time of reliability. Water pump failures on these cars often come without warning, and I didn't want to be dealing with a potential overheating/head gasket because I was too lazy to replace the water pump. I ordered the parts from Bimmerzone (through the BimmerForums.com website), and was very pleased with the transaction. The prices were very reasonable, everything was well-packed, and it arrived quickly. I'd definitely do business with them again. Removal phase: - • Confirm you have the radio code, remove negative battery cable • Removed radiator cover (4 Phillips screws), airbox (two 10mm nuts), and alternator ram air ducting (6mm hose clamp) • Remove aux fan temp sensor (plugs into radiator) • Drained (Phillips head screw) & removed radiator -I had bought a new one to replace it - If you're replacing the radiator, move the two rubber "feet" from the old radiator and put them on the new one • Drained engine block of coolant 19mm drain plug head (had to remove and reinstall O2 sensor that was right in the way of the block drain plug, covered O2 sensor hole with duct tape while the coolant was draining) • Removed upper and lower radiator hoses - 6mm hose clamps • Removed primary fan using 32mm open-ended wrench and pulley holder tool • Detached fan shroud (2 rivets) • Removed expansion tank by unclipping coolant level sensor and removing the two hose clamps that attach to the expansion tank • Removed water pump pulley - four 10mm bolts • Removed water pump - four 10mm nuts, used two 3" long M6 bolts to back out the water pump • Removed thermostat housing and thermostat (three 10mm bolts, one 13mm bolt that secures the engine lift hook) Install phase: • Water pump (four 10mm nuts) • T-stat and housing (3 10mm bolts, 2 13mm bolts for engine lift hook - longer bolt goes on the top). I installed an aluminum housing, so I used thermostat/water pump RTV along the outside edge. The instructions said it would be fully cured within 24 hours, so I waited that amount of time before adding any coolant • Radiator, and aux fan temp sensor (plugs into radiator) - remember to get the rubber bumpers off of the old radiator • Lower hose to expansion tank (hose runs along bottom of the fan shroud to the engine block) - 6mm hose clamp • Upper hose to expansion tank (hose runs along the upper part of the fan shroud to the driver's side) - 6mm clamp • Install belts (water pump/alternator first, then A/C belt) 16mm on alternator/water pump tensioner, 8mm Allen key on A/C tensioner • Rotate fan shroud out of the way with expansion tank installed • Lower radiator hose - 6mm hose clamp • Plug in coolant sensor • Rotate fan shroud back down and install 2 fan shroud rivets • Install fan (32mm open end wrench) • Install upper radiator hose - 6mm hose clamp • Connect upper expansion tank hose to radiator on driver's side - 6mm hose clamp • Replace plastic cover and alternator ram air ducting - 6mm hose clamp • Replace airbox (two 10mm nuts) For bleeding the system, I basically followed the Bentley manual: • 50/50 mix of BMW coolant (blue) and distilled water (found in cleaning supply aisle) • Front end up on ramps • Ignition on, engine off • Reservoir tank open, bleeder screw out • Cranked up the heater controls to max warm (90 degrees) on the lowest fan setting • Slowly added coolant until it no longer bubbled out the bleeder valve • Reinstalled reservoir cap and bleeder screw • Ran up to full operating temp (kept revs between 1-1.5K RPM) • Let idle at full operating temp (gauge stayed in the mid-range) • Shut down engine • Once engine was cool, rechecked the level and added as necessary Here are some pics with notes: http://s672.photobucket.com/albums/vv82/dj06482/E36/E36%20Cooling%20System/

Thanks!

BTDT... about 6 years ago... and pretty much as I remember it...

Good tip on removing the O2 sensor... in addition, I found that if you wedged a large plastic funnel into the space under the plug, it would catch most of the coolant and direct it towards your catch-pan of choice.

I actually put a mortar pan underneath the block drain plug on 4"X4" pieces of wood. The size of the mortar pan and the fact that it was up higher combined to minimize the mess. Next time I'll try the funnel trick, too - thanks for sharing!

Great timing on the post. I just did mine, and feel I must reiterate what a joy these cars are to work on. 2.5 hours was sufficient, and everything is pretty straightforward. I also discovered that the PO (or body shop: it was in an accident) had patched the expansion tank with JB weld. In any case, 100k service is done, and I'm ready for 100k more.

njansenv wrote: Great timing on the post. I just did mine, and feel I must reiterate what a joy these cars are to work on. 2.5 hours was sufficient, and everything is pretty straightforward. I also discovered that the PO (or body shop: it was in an accident) had patched the expansion tank with JB weld. In any case, 100k service is done, and I'm ready for 100k more.

I had the same experience, the car was really a joy to work on. Parts were pretty cheap (due to some great vendor competition), and there are so many DIY sites out there that it's easy to find the basics...

Now that I'm not as worried about the water pump failing, it's time for me to start driving the car much more frequently!