Cooling system

The car was slightly overheating when spinning about for any serious amount of time. It wasn’t a massive amount, but enough to justify a refresh.

There are 2 options, installing OEM parts, or installing an upgraded cooling system. I went with the later.

Mishimoto

Mishimoto seemed like the best upgrade path for me, parts are of a high quality and have lifetime warranty. I got the below parts from mishimoto:

• Mishimoto E46 Aluminum radiator.
• Mishimoto fan and shroud
• Mishimoto Radiator hoses.
• Mishimoto Racing Thermostat
• Mishimoto Water pump

OEM Parts

As well as the mishi parts I also ordered a new Mahle expansion tank and lower left hose, to complete the system.

The install

The install was pretty simple and to swap everything out only took about half a day, I’m not a mechanic but have good enough mechanical knowledge. I started with draining the radiator. I then removed all the pipes.

Since this is an auto conversion, it had a mechanical fan and secondary auxiliary fan. The clutch fan was easy to install, just get a hammer and spanner and give it one good wack, fan is off, just make sure you do it clockwise since its reverse threaded.

Next I removed the expansion tank, aux fan and radiator. All simple enough, the aux fan just bolts out, same as the radiator. The expansion tank can be a pain to get out of the car, but once its out, installed everything again is easy enough.

I then removed the water pump and thermostat, also easy enough. Just need to loosen the water pump pulley, release tension on the tensioner, slip the belt off, remove the pulley.

I started with installing the water pump, turns out the previous owner already installed a metal water pump (whoops), I replaced it with the new one anyway. Small amount of silicone, push it in, tightened to torque specs. Similar process with the thermostat, pull the old one off, small amount of silicone, push it in and torque to spec.

With those 2 installed, I then installed the new expansion tank on to the new radiator, I then slid it all into place, which was a painless process. All bolted into place. I then installed the mishimoto pipes, jobs a good one.

The fan and shroud was tricky, I didn’t know that you were supposed to get a separate controller, mishimoto say you can’t use the stock BMW controller.
How wrong they are, I have an old “black” controller which came off the aux fan. It is more than good enough to drive the fan no matter what they say. At the same time, I wired in a relay and an LED toggle switch into the dash where the old “push-to-start” button was. I wired a 5 pin relay, which was wired as below:
Controller fan + -> 87a
Battery/jump point + -> fuse -> 87
Fan + -> 30
85 -> ground
86 -> switch output
Fan -> ground

This allows the fan to be controlled by the controller when on the road, and with a flick of the switch it can go full pelt. With the original wiring I did manage to wire the fan backwards so it wasn’t cooling very well at idle or when spinning. When spinning it would overheat, I reversed the fan wires and all was sorted.

The bleeding process

The process of bleeding isn’t that bad. Turn on the ignition put the fan on the highest temperature at the lowest speed. Loosen the bleed screw and start pouring in water. When there is no more bubbles coming from the screw and its just water, keep pouring for an extra minute or so and you’re done. I then drained out some of the water, added coolant mix and anti-freeze.