Coolant Leak - Expansion? - United Bimmer Community

**chris3896** · 10-01-2008, 09:08 PM

So my 2000 323i's engine started to overheat and I noticed that there was an explosion of coolant all over my engine bay. I waited till the next day and slowly poured some coolant into the expansion. I waited a few seconds and coolant slowly leaked down from the bottom of the expansion onto the plastic underneath. I've been told that the radiator might need to be replaced but it seems like the expansion is really the only thing that is damaged. Just because the coolant leaks out of the expansion, I could probably just replace that. Does that sound right to anyone? And does anyone maybe have a tutorial or can lead me through the removal? It doesn't seem too hard. Thanks.

**oz striker** · 10-18-2008, 07:55 AM

sounds reasonable to try and jus change the expansion tank at first. how many miles have you done? I had a gradual coolant leak, never really overheated jus needed topped up every week or so and i 1st had the expansion tank replaced, but turned out my radiator matrix was all swollen and past its best, hence had that changed as well.

If you do get the radiator changed, it worthwhile changing the water pump, thermostat and drive/accesory belt also.

Found this DIY of sorts over at E46Fanatics:
http://forum.e46fanatics.com/showthread.php?t=208898

**chris3896** · 10-20-2008, 02:13 AM

yeah definitely the expansion tank. massive crack down the side haha. I didn't even notice it until after i took out the entire thing. It was a pain to get everything out but it really was more manhandling than anything. thanks to Rob for the help.

**chris3896** · 12-02-2008, 05:38 AM

yeah so we replaced the expansion tank and now it's still overheating. it's fine for the first five minutes then it blows up again. anyone have any other ideas?

motorwerks · 12-02-2008, 09:05 AM

I had nearly the same thing happen to me, and it was the waterpump. The pressure from overheating is probably what cracked your expansion tank. It is possible it's not the water pump, but rather the thermostat. Either way you'll need to get in there to find out which one it is.

**chris3896** · 12-11-2008, 02:17 AM

i'm also not getting any heat inside the car which is kind of ironic since my engine is practically blowing up...does that narrow it down any?

motorwerks · 12-12-2008, 02:29 PM

Quote:

Originally Posted by chris3896

i'm also not getting any heat inside the car which is kind of ironic since my engine is practically blowing up...does that narrow it down any?

If your pump isn't pumping, then no heat to the heater core. I stick with my story.

**brinkley** · 01-02-2009, 04:47 PM

I am fighting the same issues. My expansion cracked the other night. i went from no heat to only heat before it went out.
you may have a stuck thermostat as well. I have heard that there is a water temp sensor at the back of the block that can also go out and cause the thermo to not open.

#3 in that photo
Also a stuck water valve could be causing you to not have heat

#2 in this one

**zach22** · 08-25-2009, 10:04 PM

I had simalar issues with my 02 325i. Started to over heat and had coolant leaks. did a coolant flush and replaced the main drive belt, water pump is what caused the leaking and overheating. One of the bearings went out. I recomend changing the water pump. it could be leaking from the weap hole on the underside. luckily i caught it before the expansion tank took a crap