Cooling Improvements

The M coupe & Z3 coupe Site

One of the problems with running M coupe, M roadster, and Z3 on the track is the engine oil and water temperature are very warm. Even after installing an oil cooler one still has to consider if the radiator is getting enough cool air to keep it cool. The water temperature gauge in the pod does not reflect true water temp, BMW buffers the gauge so we don't see the swings in temperature.

It you look into the front of the the car to look for the radiator, you really can not get a good view of it, so how is cool air going to get to it? By remove the Auxiliary Fan in the front of the car one can free up the air passage to the radiator. This also opens up more area for installing an oil cooler. Removing of the AUX fan should really only be done if the Air Conditioning has also been removed. One can still remove the Clutch Fan on the engine and replace it with a SPAL fan and free up some horsepower. The Cooling Improvement Steps below outline how to do this and to maintain cooling. Auxiliary Fan is replaced with a SPAL Fan attached to the back of the radiator, which is wired into the Auxiliary Fan wiring. All the functions of the Auxiliary Fan are still there, just now being done by the SPAL fan.

Cooling Improvement Steps

Remove the Auxiliary Fan in the front of the car, this also save on weight, it's about 21lbs.
Remove the Clutch Fan on the engine, frees up a little horsepower and some room behind the radiator.
Install a SPAL electric fan onto the back of the radiator and at the same time change out the temperature switch on the side of the radiator to a lower temperature switch so the fan turns on sooner.
- Recommend the SPAL 16" Pull Fan, part number for pull should be SPA-00825(curved fan blades) or SPA-00231 (straight blades). Note curved fan blades made less noise than straight, I'd go with curved.
- If your car will still have Air Conditioning I would keep the AUX fan in front of the car and replace the clutch fan on the engine with a pull type fan mounted to the back of the radiator. The two fans listed above need 4" between the radiator and engine to fit. If you don't have this use SPA-00400. Whatever fan is use, it needs to be wired into the low speed side of the AUX fan.
- If the AC is not going to be in the car than go with a pull fan, SPA-00825 or SPA-00231. If either of the two fans will not fit go with a push fan, SPA-00401 or SPA-00232.
- Quick-mount kit part # TRI-5005 to mount fan to radiator, as listed in the Racer Parts Wholesale catalog, (800) 397-7815.
- The temperature switch is a BMW part that does require that different connections pins be installed and the fan is wired into the low speed side of the auxiliary fan connector. The switch part # is 61-31-8-361-787. It does work best to pull the radiator to installing the fan.

The photographs below help in showing how much the radiator gets covered up by the auxiliary fan. As you are looking at this try to envision the air coming into the front of our cars, it has to find it way into the opening of the aux fan, and it's going to go, for the most part, straight through the radiator. So much of the radiator is covered by the aux fan, (the housing of the aux fan, the black sections around the fan blades) that the air coming into the small openings in the front of our cars, really does not get a chance to flow easily into the radiator, the air is really getting restricted to flow because of the aux fan.

Stock Radiator and Auxiliary Fan

Photo, Copyright© Scott Galaba 1998 - 2002

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