BMW E46 Losing Coolant

rich_g85

rich_g85

rich_g85

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Another day, another problem!

My car has begun losing coolant, at a fairly rapid rate. With the expansion tank filled to maximum, by the time I've driven to work and back (10 miles) the level has fallen back close to minimum.

Reasonably confident the head gasket hasn't failed (no gunge under the oil cap). Apart from a cracked expansion tank (seems to be a common issue) what else should I be checking for?

Usual caveats apply (I'm no mechanic!)

Thanks,
Rich
 
Check all coolant pipes, connections etc. including heater ones, also check for soggy carpets, although I can't remember where the heater matrix is in the E46.
 
Thanks for the pointers chaps. Carpets are dry, no puddle under the car - although there is an under tray which needs to come off.

Hoping to try and sort this one myself, getting a bit tired of handing over ££ to my local indy every time something crops up!!

Cheers
 
E46 cooling systems are notoriously unreliable like this.

Often it can be the expansion tank itself, the black plastic which it is made from gets brittle and cracks, mine did exactly this and was squirting a fine mist of boiling coolant down into the undertray - very hard to see and it only did it when hot (pressurized).

If you are lucky it might just be a pipe, but it could be the tank or radiator (both cheap so dont worry, the system is not capable of generating a large bill regardless).
 
I had a similar problem, turned out to be the water pump. The car never over heated though which was quite amazing. Was losing coolant for a couple of weeks before it decided it had had enough and went. Might be worth checking, because they tend to go circa 100k.
 
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If it is the waterpump I suggest buying the locking tool to get the fan off, its a serious pain to do it without. (6 cylinder engines)
 
My E53 was loosing coolant this quickly, turns out the plastic surround on the radiator was cracked, near the bottom O/S.

I would return from a shop (i.e. a 10 minute timeframe) and there'd be a litre of water on the floor.
 
The radiators also tend to bow quite badly at the bottom and eventually start losing coolant.

Mine 2003 one went at 115k, it was quite expensive for a quality replacement and money was a bit tight so I fitted a £40 ebay one which has done the job well so far.
 
My old e46 dumped its coolant courtesy of a small plastic pipe at the rear of the engine block, the part was only a few quid, the majority of the bill was Labour, . I tried and quickly gave up doing it myself as access was a pig.
 
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