BMW E46 radiator replacement DIY guide.
This guide will help show you how to replace your BMW E46 radiator.
First of all I removed the undertray, pretty simple, 7 screws and 3 plastic rivets normally.
Then I pressure tested the cooling system.
Went looking for the leak and wasn't surprised to see the cause, a bowed radiator. Common with age.
Drain the coolant by undoing both blue plastic drain plugs.
Remove the passenger side brake duct(left hand side).
Disconnect the coolant level sensor.
Disconnect the coolant hose from under the tank.
Pull out the expansion tank retaining clip.
Remove the 3 plastic induction intake retaining clips and then remove the intake.
Disconnect the Mass Air Flow meter(MAF) plug, undo the MAF jubilee clip and the 2 x 10mm air filter box retaining bolts and remove the air filter box.
Remove the AUC sensor and disconnect the fan plug.
Remove the T25 fan cowling/radiator retaining screw and the plastic rivet from the opposite side then pull up and out the fan with cowling.
Pull out the 3 radiator top hose retaining clips, then remove the top hose.
Pull out the expansion tank hose retaining clip and remove the hose.
Pull up firmly and remove the expansion tank, sometimes some slight prying with a screwdriver under the tank helps.
Pull out the clip and disconnect the lower radiator hose.
Remove the T25 radiator retaining screw.(Passenger side)
Move the radiator towards the engine and then pull up and out the radiator.
It's pretty bowed! Use a screwdriver to remove the plastic trim that runs along the bottom of the radiator, it helps secure the fan cowling later.
Remove the 2 x T25 screws that secure the expansion tank securing trim to the radiator.
Here's our nice new radiator.
As it was a manual car, the shorter of the two drain bungs was fitted, this shows the left over longer bung.
The new radiator with both of the plastic trims refitted.
New expansion tank too, as the old one had flattened out O rings, as shown.
Refitting the rest of the parts is a reversal of removal, here's the new radiator all fitted.
Now it's time to bleed the cooling system.
1. Jack the front of the vehicle up onto stands as high as possible,
2. Turn the ignition on to Aux 2, Engine OFF, heater on fan setting 1 and temperature fully hot,
3. Remove the rad cap/expansion cap and remove the bleed screw from the radiator,
4. Fill the radiator/expansion tank up and keep pouring till there are no more air bubbles coming out from the bleed, using a funnel that fits tight in the expansion tank neck and filling it full of water will help push any troublesome air out, when good you can then install the bleed screw and tighten it down(don't snap it), ensure the rubber O-ring/seal is still on the screw/on the bleed hole.
5. Suck some water out so it's not full to the brim, start the car up and check coolant shoots out of the small hole on the inside of the expansion tank neck when the revs are held up, if it does then run the car up for 30 seconds, then switch it off and repeat steps 3 onwards to ensure no more trapped air is in the system,
6. Refit your radiator cap and run the car up, check for heat from the vents when the car is warm, then carry on and check if over heating still persists. You may have to bleed troublesome cars again afterwards.(but very rare).
7. If all is good then check the water level again in the morning when cool.