coolant smell under bonnet when hot

J

jamie_z4

Veteran
Right, after having so many e46's with the M54 & its catastrophic cooling system, was wondering if anyone could give me a clue weather this is normal,

when my car is warm *(2.5i N52) when you lift the bonnet, it smells sweet like coolant, now is this normal? Or should i be worried? It isn't loosing any coolant, the levels remain the same & when i initially looked at it on the test drive , i opened the coolant cap whilst engine was running & because of the little jet on the RHS of the filler neck a small amount spilled down the side of the coolant bottle. Now , i've been told it smells for weeks after you've spilled it due to the nature of coolant it doesnt just 'evaporuate' so might be that, but it was such a small amount i didn't think i'd smell it all around the engine bay if that makes sense...


any one put my mind at rest? or worry me futher?

No evidence of any leaks on the nappy etc.

Kind regards!

Jamie
 
If it is not losing coolant and not running hot I would not worry about it. My M54 runs at 90 degrees plus or minus 3 degrees. The cap on the expansion tank is a blow off valve and may release excess pressure in the system from time to time. Even if it expels air with no liquid you would get the odour.
 
yeah my mate @ BMW said about the cap releasing pressue, though it makes you wonder if its bad news if its releasing pressure, theres too much pressure in the system?

Thanks for the quick reply GreyZed.
 
It's most likely going to be a cracked expansion tank. Very common problem and will release mainly vapour to start, but in some cases releases liquid coolant. 99% of the time you see no drips or liquid, but the coolant will go down in time.
 
That would be the case for the M54 No ? I've never seen any documented Cracked expansion tanks for the N52 engine with its revised cooling system.
 
I've replaced about 10 expansion tanks on various e46's - no weeping round the bottom of the tank , already ran my fingers around it after a long hard drive last night (& burned my arm in the process :( )
 
jamie_z4 said:
That would be the case for the M54 No ? I've never seen any documented Cracked expansion tanks for the N52 engine with its revised cooling system.
Click to expand...

Fair point - hadn't noticed the N52 spec.
 
cj10jeeper said:
jamie_z4 said:
That would be the case for the M54 No ? I've never seen any documented Cracked expansion tanks for the N52 engine with its revised cooling system.
Click to expand...

Fair point - hadn't noticed the N52 spec.
Click to expand...

afaik the n52 and m54 in the e85 use the same expansion tank and tank cap.

Anyway, if your engine smells like coolant or if coolant is spilled, you wash your engine with water so that all the coolant is washed away.
You don't want coolant lying/dripping around, because if it stains or smells, it makes leak detection very hard.
Coolant leak detection isn't easy anyway.

That is apparently also the case in this topic. If the coolant was cleaned right away you'd have your answer.

How many miles have you driven since you discovered the smell? And how long were those trips?
 
ah so they do! Ffs, its the e90 with the N52 i'm thinking of that has the different exp tank, its situated in a different area of the 'bay & has a different shape.

will give it a good wash tonight - cheers.
 
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