What Antifreeze for 2001 E46?

t3kno_tr0n|c · 4 Dec 2010 at 10:51

[TW]Fox;17926328 said:
The more important question is why are you topping it up? Its a sealed system and it doesnt need topping up unless there is a problem.

All systems need topping up a tiny bit after a few years.

Its not actualy a sealed system, there is valve in the header tank for a start, and the caps are never airtight.

Jonnycoupe · 4 Dec 2010 at 11:01

t3kno_tr0n|c said:
All systems need topping up a tiny bit after a few years.

Its not actualy a sealed system, there is valve in the header tank for a start, and the caps are never airtight.

Is that why they have pressure caps, typically in the region of 1.3 bar? They are airtight.

t3kno_tr0n|c · 4 Dec 2010 at 11:03

Jonnycoupe said:
Is that why they have pressure caps, typically in the region of 1.3 bar? They are airtight.

in an ideal world yes. In reality they always leak a tiny bit of pressure. Due to different expansion ratios between the cap material and the tank material, and other factors also.

Jonnycoupe · 4 Dec 2010 at 11:05

That leakage is predominatly air rather than fluid.

I think the water pump vent system is a more likely candidate for any 'usual' coolant loss. That doesnt feature on all setups though.

t3kno_tr0n|c · 4 Dec 2010 at 11:09

Still, I think if you have a system that maintains its exact level for more than 2/3 years you are doing exceptionally well.

[TW]Fox · 4 Dec 2010 at 12:58

t3kno_tr0n|c said:
Still, I think if you have a system that maintains its exact level for more than 2/3 years you are doing exceptionally well.

His has more than just not maintained its exact level - his header tank is almost dry!

The pressure cap only opens if there is excessive pressure in the system.

Relentless81 · 4 Dec 2010 at 13:08

[TW]Fox;17926328 said:
The more important question is why are you topping it up? Its a sealed system and it doesnt need topping up unless there is a problem.

I wouldnt say thats strictly true, mine was down slightly and I asked a main dealer to investigate it and they couldnt find a problem and assured me that because its long life its never been changed, I then asked why has it not been topped up if it has full main dealer history and they couldnt answer that

But they did say they inspected it and its probably not been topped up because always been between min and max levels and it was nothing to be concerned about so that did me

Edit : Obviously mine isnt a BMW

[TW]Fox · 4 Dec 2010 at 13:08

Relentless81 said:
I wouldnt say thats strictly true, mine was down slightly

You have an M54B30 engine as well? I didn't realise that.

I'll say it again - the cooling system on these cars is a sealed, pressurised system. If you've lost enough coolant that the float is resting on the bottom of the header tank, this is wrong. This is not normal behaviour.

Relentless81 · 4 Dec 2010 at 13:10

I've just edited to say its not a BMW

t3kno_tr0n|c · 4 Dec 2010 at 13:16

[TW]Fox;17929055 said:
You have an M54B30 engine as well? I didn't realise that.

I'll say it again - the cooling system on these cars is a sealed, pressurised system. If you've lost enough coolant that the float is resting on the bottom of the header tank, this is wrong. This is not normal behaviour.

No thats a correct statement to make.

However, I would suggest that a small top of around 1 or 2 cm every couple of years is normal, with evaporation and heat cycling of the fluid.

For it to be empty is obviously rather worrying thats for sure, and that must be looked at sooner or later depending on the timescale of the loss.

Cupra · 4 Dec 2010 at 13:22

id be a cheap skate and buy a new top for the header tank as thats nearly always to blame

then flush the whole system and add new so you know the ammounts are correct

[TW]Fox · 4 Dec 2010 at 13:26

Cupra said:
id be a cheap skate and buy a new top for the header tank as thats nearly always to blame

Are you speaking generally? I don't think the header tank itself is 'nearly always to blame' for cooling system problems on a 330i at all.

Oxide™ · 4 Dec 2010 at 14:00

OT: After next weeks service I want to follow this guide http://www.impee.co.uk/transmission_fluid_change.htm and use Redline D4 ATF. I know BMW say the oil is for life but I can't help looking at the gunk that comes out in the pics and also it may help with notchy gear changes (and cheaper than replacing part # 23117542726)

Cupra · 4 Dec 2010 at 14:15

[TW]Fox;17929189 said:
Are you speaking generally? I don't think the header tank itself is 'nearly always to blame' for cooling system problems on a 330i at all.

ive known 3 people losing water from 330i's and 2 were the pressure cap other was head problems

for the sake of a few quid its well worth it ohh and it looks new too

[TW]Fox · 4 Dec 2010 at 14:16

How strange, of all the people I've known, including myself, with these problems, none have been the pressure cap or the head.

They are usually the radiator, infact.

Oxide™ · 6 Dec 2010 at 19:27

bought BMW antifreeze today and topped up with around 300ml - temp is now rock solid in the middle rather than slightly to the right of center

[TW]Fox · 6 Dec 2010 at 19:41

Oxide™ said:
bought BMW antifreeze today and topped up with around 300ml - temp is now rock solid in the middle rather than slightly to the right of center

Whoa you had temp issues as well?! So there was so little coolant in the system that it began to overheat?

How long was it slightly right of centre for?

I suspect there is something wrong here!

OllyM · 6 Dec 2010 at 19:42

You definitely have a problem then - the temperature gauge is damped and unless something is wrong shouldn't move off the centre position.

Oxide™ · 6 Dec 2010 at 20:03

Just 1mm right of centre - may have been like that for a week since the car was frozen solid at work under the snow - only drove it 4 times since, short 7 miles each way.

[TW]Fox · 6 Dec 2010 at 20:11

Oxide™ said:
Just 1mm right of centre - may have been like that for a week since the car was frozen solid at work under the snow - only drove it 4 times since, short 7 miles each way.

The BMW temperature guage works in a strange way. As Olly said, it is damped - the display on the guage is not a realtime indication of coolant temperature. It is designed to slowly move towards the centre mark, where it will then stay until you shut the engine down unless the engine temperature moves outside of normal operating range, where it will then begin to move.

Therefore it will only ever move to the right if the car is beginning to overheat. Snow on a car wont cause the engine to overheat.

This, coupled with the fact your coolant header tank was virtually empty, points to the car having some sort of problem. It's either using coolant, or its leaking coolant.