E46 Cooling System
Discussion
Hi All,
I looked under the bonnet of my 2003 E46 330Ci yesterday and found what looked like a small explosion had gone off near the expansion tank on the right hand side (see below for pics):
The car appears to be loosing a very small amount of coolant, but not significant enough to cause overheating or the coolant warning light to come one.
I had a look with a torch this evening and could clearly see a small puddle of coolant on the engine under tray on the right hand side and there it was moist on the back of the headlight assembly & right hand side of the radiator area.
My first thought is that this seems to be a split expansion tank (I had a similar but much more ovbious leak on my previous E46 which was this).
Does anyone else have any experience of this or any knowledge to help me diagnose further? I need the car for some long journeys at the weekend so I need to get this sorted quite quickly.
Any help would be greatly appreciated!
I looked under the bonnet of my 2003 E46 330Ci yesterday and found what looked like a small explosion had gone off near the expansion tank on the right hand side (see below for pics):
The car appears to be loosing a very small amount of coolant, but not significant enough to cause overheating or the coolant warning light to come one.
I had a look with a torch this evening and could clearly see a small puddle of coolant on the engine under tray on the right hand side and there it was moist on the back of the headlight assembly & right hand side of the radiator area.
My first thought is that this seems to be a split expansion tank (I had a similar but much more ovbious leak on my previous E46 which was this).
Does anyone else have any experience of this or any knowledge to help me diagnose further? I need the car for some long journeys at the weekend so I need to get this sorted quite quickly.
Any help would be greatly appreciated!
When mine cracked it let go most of the coolant in a few seconds. Rather inconvenient! I also couldn't see anything wrong with the tank, until I poured water in and it all pissed out again. I think it expands as it heats up and when cold/empty shrinks down again.
At least you have caught it before being at the other end of your long journey.
Plenty of DIYs out there on how to do it and a dealer should get the parts in next day if it's not in stock. Check the water pump, ATF cooler (if fitted), hoses and thermostat while it's drained, and use the right coolant.
At least you have caught it before being at the other end of your long journey.
Plenty of DIYs out there on how to do it and a dealer should get the parts in next day if it's not in stock. Check the water pump, ATF cooler (if fitted), hoses and thermostat while it's drained, and use the right coolant.
Edited by john_p on Monday 22 November 22:24
john_p said:
When mine cracked it let go most of the coolant in a few seconds. Rather inconvenient! I also couldn't see anything wrong with the tank, until I poured water in and it all pissed out again. I think it expands as it heats up and when cold/empty shrinks down again.
Thats what the expansion tank on my old E46 318i did, was very annoyed to come back to the coolant all over the floor in my supermarket car park!I've just looked at paperwork I have for the car & the sticker on the side of the unit and it is the original from 2003 (it has now completed 133k miles) so I think I've been quite lucky for it to have lasted this long from some of the stories I've been reading on the web.
Turned out to be the radiator (did a pressure test).
Rad, expansion tank & water pump all being replaced today.
Would have liked to do the work myself but dont have time & need the car for work so its with the BMW independent that I use - looking forward to having the car back, but not looking forward to the bill!
Rad, expansion tank & water pump all being replaced today.
Would have liked to do the work myself but dont have time & need the car for work so its with the BMW independent that I use - looking forward to having the car back, but not looking forward to the bill!
I use Chris Plummer in Aldershot.
He's done work on both the BMW's I've owned and has always been very good.
He's done work on both the BMW's I've owned and has always been very good.
I can confirm my expansion tank on my Alpina B3 3.3 went pop last week. The failed expansion tanks was caused by the failure of the Automatic thermostat in the base of the tank. There must be an inherent design flaw for so many to fail. (See many threads)
When initially purchasing the OEM header tank from BMW, I asked what would make the tank fail. “They just go sometimes” was the reply.
Only to find when stripping the unit down, that the thermostat had also failed, which ultimately lead to high pressure and tank failure at a weak point?
A question to BM, is why don’t they know one design flaw leads to another can’t the thermostat be designed more robustly? Ah yes, you wouldn't sell so many parts then would you!!
When initially purchasing the OEM header tank from BMW, I asked what would make the tank fail. “They just go sometimes” was the reply.
Only to find when stripping the unit down, that the thermostat had also failed, which ultimately lead to high pressure and tank failure at a weak point?
A question to BM, is why don’t they know one design flaw leads to another can’t the thermostat be designed more robustly? Ah yes, you wouldn't sell so many parts then would you!!
darren-9da0g said:
Hi guys any help would be much appriciated my heaters stopped blowing heat so changed water pump (as was a little bearing play) also changed thermostat gave full bleed but still have no heat any ideas thanks.. sorry its a bmw 320ci 2.2 2001
When you you say you’ve bled it; how did you do this?These, like the E39s, like to have their front end raised a touch as well.
Did you really let it run and let all the bubbles escape, did it bleed itself via the electric self-bleed, or did you get the engine going straight away with heaters up full etc?
This is a good how-to: https://youtu.be/MQzoAXn_90U
darren-9da0g said:
Hi guys any help would be much appriciated my heaters stopped blowing heat so changed water pump (as was a little bearing play) also changed thermostat gave full bleed but still have no heat any ideas thanks.. sorry its a bmw 320ci 2.2 2001
Its your final stage resistor aka Hedgehog - very common problem on the E46s.Can be a bit fiddly as it located to the upper left of the foot pedals
Thanks for replying i thought fsr/fsu was for fan speed only and they go from fast to slow as normal ????. iv done another full bleed an flushed the heater core valve an got a little heat. I rev up to 3500rpm a little bit more heat then tick over bak to little heat all pipes are hot except for the smaller pipe at bottom of expansion tank ????? Any more help you cud giv would be amazing cus im baffled
darren-9da0g said:
Thanks for replying i thought fsr/fsu was for fan speed only and they go from fast to slow as normal ????. iv done another full bleed an flushed the heater core valve an got a little heat. I rev up to 3500rpm a little bit more heat then tick over bak to little heat all pipes are hot except for the smaller pipe at bottom of expansion tank ????? Any more help you cud giv would be amazing cus im baffled
hi, its 100% the FSR, I had the same problems as you and the FSR sorted the heater outGassing Station | BMW General | Top of Page | What's New | My Stuff