Radiator replacement

Hi I have an BMW E46 2002 320i Saloon. I noticed a water leak from the radiator at the weekend comming from the top at the front of the engine bay. I have located a new radiator on the internet and wondered whether this is a job that I can carry out myself instead of paying a dealer to do it. Has anyone done this job and how difficult is it to do at home?

It is simple, but make sure you change expansion tank and radiator cap too. Do some research, lots of info on cooling system overhaul.

Replacing parts seem to be easy, but taking coolant out and putting new in right way is bigger issue.

Took me couple hours to get home from garage when needed to stop and cool off/ add coolant/ let air out every once in a while.

So it's good idea to see what else should be replaced in cooling system and do it at the same time.

Originally Posted by QAfred

It is simple, but make sure you change expansion tank and radiator cap too. Do some research, lots of info on cooling system overhaul.

why do I need to change expansion tank and radiator cap?

Because you have to remove the expansion tank to get the radiator out and you would not want to re-install a 10 year old tank after installing a new radiator. They expand at a micro level every time you get the car up to running temp. They have a limited amount of cycles before they crack. Typically they blow every 70 k or so. If it is an automatic you should also change tranny thermostat...#4.

Hi. It is relatively easy job to replace the radiator, I did mine outside the house. I would buy an original radiator as I bought an Ebay one and it fitted but wasn't just right.
Doing the expansion tank is just a precautionary measure as they fail, (mines did). Jim

probably a silly question, but are u sure that ur radiator is leaking water and not some hose or some other part related to the radiator?
it's very rare (at least to me, never heard of such thing) that a BMW E46 radiator leaks, unless it was damaged. usually most of the times it's some plastic that gets old enough that it cracks due to high heat, or some hose

Not a silly question at all. At first I noticed a "puff" of what looked like steam comming out from under the bonnet. I put some "radweld" in the radiator to see if it would fix the leak. I left the car running for half an hour as directed by the "radweld" and it did seal the leak.

It was only when I drive the car that it started to leak again. I guess it was the additional pressure build up from the system. The leak is right at the top of the radiator in the middle. I am not an expert but I am not aware of any hoses running through this location?

I will try and do some more investigative work and possibly remove the radiator at the weekend to identify exactly where the leak is before I go and purchase a new radiator. In a way I am sort of hoping that it is a leak from something else like a fitting or a pipe as this will be easier to rectify.

It's good to wipe any extra mess off while you're there.
I didn't... so in the morning i was afraid it still leaks, but apparently all coolant stay inside now... i think...

Ofcourse it's possible that water pump wasn't only faulty part...

It's not a difficult job. As others have said, certainly replace the expansion tank. And while you're at it, replace all the hoses and probably the thermostat. If the water pump is the original, consider replacing that too. This starts to become a bit of work, but would you rather replace it on your schedule, or have it go boom out on the road?

Follow the cooling system bleed procedure carefully to get all the air out of the system.

Some pics from my replacement: http://www.bimmerfest.com/forums/sho...d.php?t=615786

Oh, and if you replace the lower radiator hose, plan on replacing the temperature sensor too, because the shrunken O-ring won't seal properly when you replace it and it'll leak. I got away with it by wrapping a bit of teflon plumber's tape on the sensor beneath the O-ring to bulk it up a little bit, so you might try that.

-Bob

Originally Posted by rgk330i

Oh, and if you replace the lower radiator hose, plan on replacing the temperature sensor too, because the shrunken O-ring won't seal properly when you replace it and it'll leak. I got away with it by wrapping a bit of teflon plumber's tape on the sensor beneath the O-ring to bulk it up a little bit, so you might try that.

-Bob

good stuff Bob. Another option - You can actually just replace the o-ring with rubber plumbing o-ring from hardware store:

O-ring only 5/16" ID 9/16" OD and 1/8 thick" failure of the sensor is rare and it's a few bucks for a pack of orings vs $20 for a new sensor. not much $$ either way.

Thanks for your help people. I removed the radiator this weekend in the pooring rain! I followed advice from here and the whole job went very smoothly. It took about an hour as everything was so easy to unplug or unclip with all the quick release fixings. I removed the fan, removed all the hoses, unplugged all the electrical bits, removed the expansion tank and simply lifted the radiator out of the car. I did not even go underneath the car during this process - everything was done from above.

I have ordered a new radiator which should be here tomorrow. The new radiator will be installed this weekend. hopefully it will all go back in as smoothly as it came out.

well the new radiator is in and seems to be working ok with no leaks. I ran the engine for half an hour and the temp was sitting just above the centre mark on the temp guage. I did have the yellow warning light on the dash though! I filled the radiator and opened the bleed screw next to the filler cap. I refilled the fluid level several times but the yellow warning light will not go off. eventually I looked into the filler cap and could see the small return flow of coolant comming out of the small hole in the side of the filler tube.

Do I need to do anything else to bleed the rest of the system - ie the heater hoses etc?

Will the yellow warning light eventually go off on its own?

I guess the yellow warning light is low level in the radiator?

Do a search for filling and bleeding coolant system. Filling and bleeding should be done with engine off, heat temp up full and blower on full i believe. But do a search as I might have forgotton a thing or two.

I guess it helps if the expansion tank low level sensor is plugged in

bled the system again and all working fine now whoop whoop

saved hundreds doing the job myself!

thanks for your help

Originally Posted by white_lancer

bled the system again and all working fine now whoop whoop

saved hundreds doing the job myself!

thanks for your help

Basically you can never be sure if those "professionals" would do it right at once. So few nervous moments about forgetting something, shouldn't hurt too bad.

Whilst i'm in confession mode I also managed to snap off the expansion screw in the hole. I purchased a new one. I heated a screw driver up and inserted this into the broken screw. When it cooled down I simply unscrewed the broken piece. Simples.