BMW E46 Coolant Leak

BrokenSpiral

Hi Guys,

I have recently purchased an E46 BMW 3 Series Coupe (2004 model) and yesterday the coolant light came on. So I topped it up wth coolant and 15 mins later it came on again. When the engine had cooled down I checked and it looks like there is a leak in the coolant tank. I have heard that it can cost up to 500 euro fix at a bmw garage. Anyone else had this problem or have any suggestions?

Andrewf20

I had similar symptoms (overheating) a month ago, except I dont have a "Coolant low" light, just an engine temperature dial in my E36.

Some quick notes, some real obvious, others not so much:

- Check if engine is overheating
- Check viscous fan coupling.
- Check for whiting in the oil (on dip stick & filler cap), which would hint at a head gasket issue. If this is suspicous, check if oil level on dip stick rising.
- See if coolant level drops when engine not running. i.e. Top up at night and check the following morning, perhaps with paper under the car in a dry garage.
- Run engine from cold with expansion tank cap off, water should be gushing into it, to suggest that the water pump impeller is still operational. This should also remove any air locks that may exist in the system. (This seemed to fix my issue with dropping coolant levels in my car). Again put some newspaper under car to hint at potential leak sources.
- Check all coolant hoses in engine bay, check floor in car foot well not soggy.
-Check for perished rubber seal on expansion tank cap. Hot coolant under pressure may be seeping out here and may evapourate quickly, so that it looks dry after a few minutes.


Id recommend AC Car sales near Christchurch or Robert Furley in Kells to check it out if its nothing obvious. They have reasonable rates and are good. I wouldnt recommend the main dealer with their extortionate labour rates.

Anan1

This may seem obvious but you say you only bought the car recently - is it still under warranty? If non, i'd second the recommendation for AC car sales.

DublinDilbert

Hi,

If the coolant low light is coming on after only 15mins, it must be leaking fairly fast... Can you see where the coolant is coming from? is there alot of water down on the plastic pan under the engine? to drain that amount of coolant in 15 mins is a pretty big leek, should be easy to spot.

The E46 uses all "push fit" connectors for all of the water connections... check that these are all ok, and pushed home correctly... I'd bet it's one of these connections that is leaking... If it is there's an o-ring inside of each connection that can be changed, although most places change the entire pipe ( which comes complete with new o-rings from BMW )

michaelanthony

I had a similiar problem and it was a bearing on the water pump. The fluid would gush out after the engine heated and it expanded/pressurised.

rebel.ranter

One important question to ask:
Is there signs of coolant leaking out? i.e. is a there a sign of an external leak in the engine bay, a puddle on the ground? If not it could be a serious problem.

I wouldn't advise driving the car around with the car losing coolant. BMWs use a pressuriesd cooling system. If an air-lock develops it could cause an overheating problem & bye bye engine. Check all the pipe connections, also check for cracks on the "necks" of the radiator (pieces where coolant hose connects to).
Also have a look at the botom of the radiator, there should be a little blue coloured plug down there, the seal can sometimes go on this. It's very cheap to replace.

galwaytt

afaik, there's a plastic elbow somewhere near bottom of block, on r.h.s, made of plastic that's also prone to go awol..........went in sis-in-law's too.......

JohnCleary

Friend of mine had an E46 318 with leaking coolant, it was the water pump. Replaced it himself quite easily IIRC, worth a check, he could see it weeping out of the pump