BMW E46 Expansion Tank Leaking - Again
Discussion
Dear all,
I hope you are all well.
I have a BMW E46 which has had 4 expansion tanks over the last 4 years (yes you read that right) and I am now looking at why I have yet another empty expansion tank.
I have been considering buying a metal one, however wondered if anyone had any advice on what I can do to the engine to reduce possibility of damaging any further plastic ones. I am also wondering if anyone has any thoughts on plastic welding to fix the original plastic tank?
On a side note my car is converted to run on LPG.
Thanks in advance,
I hope you are all well.
I have a BMW E46 which has had 4 expansion tanks over the last 4 years (yes you read that right) and I am now looking at why I have yet another empty expansion tank.
I have been considering buying a metal one, however wondered if anyone had any advice on what I can do to the engine to reduce possibility of damaging any further plastic ones. I am also wondering if anyone has any thoughts on plastic welding to fix the original plastic tank?
On a side note my car is converted to run on LPG.
Thanks in advance,
Two trains of thought come to mind.
Firstly, what brands of expansion tank have you been using? Given your track record I would stump up what is not a lot of cash for an OEM one from BMW. If it fails promptly they should stand behind their warranty.
Secondly, have you considered the system is running at an excess level of pressure? A faulty cap could be preventing excess pressure from releasing. Why you might have excess pressure is a little outside my knowledge, but typically its due to a restriction or because the crank case is pressurising it. Food for thought.
Firstly, what brands of expansion tank have you been using? Given your track record I would stump up what is not a lot of cash for an OEM one from BMW. If it fails promptly they should stand behind their warranty.
Secondly, have you considered the system is running at an excess level of pressure? A faulty cap could be preventing excess pressure from releasing. Why you might have excess pressure is a little outside my knowledge, but typically its due to a restriction or because the crank case is pressurising it. Food for thought.
d_a_n1979 said:
Agree with the question above, which brands have you been using?
OEM BMW is Hella Behr IIRC but Meyle and Febi Bilstein should be spot on too.
The OEM one isn't that expensive either as far as I'm aware
Hi,OEM BMW is Hella Behr IIRC but Meyle and Febi Bilstein should be spot on too.
The OEM one isn't that expensive either as far as I'm aware
Thank you for your responses, one of the early ones was cheap n nasty but I was new to BMW so to be honest had no idea. I then had two really good looking ones which looked good and strong. However the one I had installed 12 months ago was a Hella one for sure. I agree this type of part should not be replaced with el cheapo after market ones.
Someone suggested to me I get a 1.3bar cap, what are your thoughts on this? I had a 1.3 before but the tank cracked up as a result of head gasket leakage (which was replaced 3 or 4 years ago or so) and in my opinion this means the 1.3 bar means nothing because it didn't release the pressure letting the tank crack up anyway???
d_a_n1979 said:
Agree with the question above, which brands have you been using?
OEM BMW is Hella Behr IIRC but Meyle and Febi Bilstein should be spot on too.
The OEM one isn't that expensive either as far as I'm aware
How can we test the cap? How would I know if the crank case is doing anything wrong? The head was shaved when the head gasket was replaced and I understand that makes the system slightly smaller. The car came back with a cold start misfire after the headgasket was replaced and after a lot of effort I have not be able to fix it. As long as I start moving the moment I turn the car on its ok. However in the depths of winter when its minus 5 I have to rev for one minute before setting off or th emisfire code will go off when I get to a set of traffic lights one mile away.OEM BMW is Hella Behr IIRC but Meyle and Febi Bilstein should be spot on too.
The OEM one isn't that expensive either as far as I'm aware
To add, when the ET has been changed is the system bleed properly? I'm not judging here as needs to be done methodically.
Excess air can cause additional pressure.
Other possibilities could be a faulty thermostat. When they fail they fail on the open side. However there is a possibility its closed and is over heating excessively and blowing your ET? But I suppose the tell tale sign of that would be the temp guage would be going into the red - does it?
Rather than change the cap on this I'd be looking at the root cause. Should get 60k or so out of a genuine /hella/behr ET.
Bloody cooling system on these things!
Sorry another question. Can you see the leak on ET? Or is just that's its empty? Because if it's empty it could be leaking elsewhere within the system... I know this as I have been on this journey...
Excess air can cause additional pressure.
Other possibilities could be a faulty thermostat. When they fail they fail on the open side. However there is a possibility its closed and is over heating excessively and blowing your ET? But I suppose the tell tale sign of that would be the temp guage would be going into the red - does it?
Rather than change the cap on this I'd be looking at the root cause. Should get 60k or so out of a genuine /hella/behr ET.
Bloody cooling system on these things!
Sorry another question. Can you see the leak on ET? Or is just that's its empty? Because if it's empty it could be leaking elsewhere within the system... I know this as I have been on this journey...
Edited by ahas on Saturday 3rd October 13:50
IAmTheWalrus said:
Everything comes from China, including $1000 apple Iphones, its cheaper labour.
Tell me about it...2020 MacBook Pro 13" - £2600, sent back twice due to failing Logic Board
Kicked off with Apple; got a refund and went back to my 2012 Mac Mini that's never failed me and has zero issues!
ahas said:
To add, when the ET has been changed is the system bleed properly? I'm not judging here as needs to be done methodically.
Excess air can cause additional pressure.
Other possibilities could be a faulty thermostat. When they fail they fail on the open side. However there is a possibility its closed and is over heating excessively and blowing your ET? But I suppose the tell tale sign of that would be the temp guage would be going into the red - does it?
Rather than change the cap on this I'd be looking at the root cause. Should get 60k or so out of a genuine /hella/behr ET.
Bloody cooling system on these things!
Sorry another question. Can you see the leak on ET? Or is just that's its empty? Because if it's empty it could be leaking elsewhere within the system... I know this as I have been on this journey...
Yes bled properly.Excess air can cause additional pressure.
Other possibilities could be a faulty thermostat. When they fail they fail on the open side. However there is a possibility its closed and is over heating excessively and blowing your ET? But I suppose the tell tale sign of that would be the temp guage would be going into the red - does it?
Rather than change the cap on this I'd be looking at the root cause. Should get 60k or so out of a genuine /hella/behr ET.
Bloody cooling system on these things!
Sorry another question. Can you see the leak on ET? Or is just that's its empty? Because if it's empty it could be leaking elsewhere within the system... I know this as I have been on this journey...
Edited by ahas on Saturday 3rd October 13:50
Thermostat was new few year ago.
Never goes into red.
I have not established where the leak is yet. I had nightmares the other year looking for leaks then. Replaced a two foot pipe and the stealership wanted £40.
Other pipes were replaced some years ago but owing to weather today I have not been hunting..
ahas said:
Yeah it could well be that your ET is fine but leaking elsewhere.
As you say rain don't help!
I had a leaking heater core. C£30 for the radiator couples hours to fit. That was the main cause of my e46 losing coolant.
When you have the heating on can you smell coolant in the cabin?
Nope.As you say rain don't help!
I had a leaking heater core. C£30 for the radiator couples hours to fit. That was the main cause of my e46 losing coolant.
When you have the heating on can you smell coolant in the cabin?
Pressure test it when cold using a cap with a valve in it to apply the pressure. You can either buy them ready to use or make one using an old cap and an inner tube valve. It's much easier to find leaks when they don't evaporate before hitting the floor due to landing on hot engine components.
First time poster
Just to add that I have a 325CI which had a Modine expansion tank which was a replaced a few months back as it was about to go with a Hella unit. The Modine ET had more heft to it and seemed more robust as opposed to Hella unit. I was trying to find a Modine ET to no avail. They're available over in the states quite readily but seem to be non-existent here. Not sure if Modine still OEM to BMW when you buy it from the dealership.
Just to add that I have a 325CI which had a Modine expansion tank which was a replaced a few months back as it was about to go with a Hella unit. The Modine ET had more heft to it and seemed more robust as opposed to Hella unit. I was trying to find a Modine ET to no avail. They're available over in the states quite readily but seem to be non-existent here. Not sure if Modine still OEM to BMW when you buy it from the dealership.
Gassing Station | BMW General | Top of Page | What's New | My Stuff