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Old Tue, Feb-15-2011, 02:43:24 PM   #2
We've had one yes, what about second breakfast?
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Join Date: Feb 2007
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Location: North of Baltimore

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Default Re: ***The cooling system thread - overhaul DIY***

Set-up: I work in a very small garage, so space was a little tight. I did this entire project with the front of the car up on ramps. The red blanket is my drip catcher. I use taped notes on the wall to remember steps, torque values and make notes.

I also use small bags to organize fasteners/clips

The intake needs to be removed. The top of the airbox can simply be rotated out of the way as shown, but the lower section needs to be removed. In the picture, you can see the cover of the xenon control unit lifted up. This gives you access to the two bolts holding the lower half of the airbox. It simply lifts out.

Head underneath the car and take off the plastic panel underneath the engine and remove the two screws that hold the oil cooler. The oil cooler can be pushed back a bit, but I like to support it with something so it doesn’t stress the lines too bad.

Unplug the connection on top of the radiator and the temperature sensor in the lower hose. There is also a wiring assembly that is mounted on the passenger side of the fan shroud, it simply lifts out. These three items can be tucked away for now so they don’t get wet.

Remove the fan with your fan nut tool (32mm). There is a secondary tool that holds the water pump pulley steady while you break the fan free, but it’s not really necessary. Some people are able to get the fan nut lose by hitting it with a mallet, but mine didn’t seem to want to move. I was able to get mine loose by using a long thin screwdriver to keep the pulley still. Note: if you haven’t heard it before, the fan clutch nut is reverse threaded. Think righty loosey, lefty tighty.

I found it easiest to remove the fan by dropping it out of the bottom of the car. Once the fan is out, you can remove the fan clutch. It’s held on by three 5mm hex bolts. Make sure to take a good look at the fan when you remove it so you put the new clutch in the correct way. I didn’t…more on that later. Be careful when tightening the new clutch in, you don’t want to crack the plastic fan. Torque spec is 10Nm (89 in-lb or about 7 ft-lb). You can also remove your belts now. The Bentley manual recommends that you mark the rotation of the belts so that they can be re-installed the same way. I’m not sure why this matters, but I did it anyways.
Edit: It's easiest to remove the fan assembly and the shroud together at the same time. Removing the fan with the shroud still in place is difficult.

Now you can drain the old coolant. E46 M3’s don’t have a radiator drain plug, which is kind of a pain. The simplest way to get around this is to drain fluid out of the temperature sensor in the lower radiator hose.

Since the fluid is going to drain up out of the sensor hole, I covered it with an upside down funnel to reduce the mess. Pull the plug out and let the fluid drain. Since the rest of the system is still closed, not too much will drain out. To ensure you drain all the fluid, turn ignition switch on (don’t start the engine) and set your temp setting to full warm. With the funnel in place, open the bleeder valve and let the fluid run. I used this method and was able to keep spills to a minimum.

Old and new temperature sensor.

Last edited by BlazenXLT; Fri, Dec-30-2011 at 12:59:52 PM. Reason: photo editing
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