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Expansion tank nightmare (never ending)

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4.5K views 33 replies 10 participants last post by  deroy  
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#1 ·
My expansion tank had developed a crack so I've replaced it with an aftermarket one ... twice.. got them on ebay for 30$, both of them had developed leak off the bottom hose connection within a couple of weeks. Then Iv'e decided to spend some $ on an OEM original BMW one, got it yesterday... and it's leaking now from the top fitting which is completely loose.

What am I doing wrong here ? is it such a problem to get an expansion tank which has proper fitting diameters? I've bought another one OEM on amazon, will try it in a day or two, but after that I'm giving up, I'll just have to go to the dealer and pay probably 500$ to change the expansion tank. :dunno::mad::mad::mad::mad:
 
#2 ·
shorkun said:
My expansion tank had developed a crack so I've replaced it with an aftermarket one ... twice.. got them on ebay for 30$, both of them had developed leak off the bottom hose connection within a couple of weeks. Then Iv'e decided to spend some $ on an OEM original BMW one, got it yesterday... and it's leaking now from the top fitting which is completely loose.

What am I doing wrong here ? is it such a problem to get an expansion tank which has proper fitting diameters? I've bought another one OEM on amazon, will try it in a day or two, but after that I'm giving up, I'll just have to go to the dealer and pay probably 500$ to change the expansion tank. :dunno::mad::mad::mad::mad:
Click to expand...
When you say the top fitting is leaking do you mean the cap? If it is the cap, is this the original cap, and aftermarket cap, or the one that came with this new OEM tank? I have read about some being a bad fit.
 
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#5 ·
#15 ·
shorkun said:
My expansion tank had developed a crack so I've replaced it with an aftermarket one ... twice.. got them on ebay for 30$, both of them had developed leak off the bottom hose connection within a couple of weeks. Then Iv'e decided to spend some $ on an OEM original BMW one, got it yesterday... and it's leaking now from the top fitting which is completely loose.

What am I doing wrong here ? is it such a problem to get an expansion tank which has proper fitting diameters? I've bought another one OEM on amazon, will try it in a day or two, but after that I'm giving up, I'll just have to go to the dealer and pay probably 500$ to change the expansion tank. :dunno::mad::mad::mad::mad:
Click to expand...
Dumb question but you're not overfilling the coolant are you? With the sealed cooling system, the air pocket above the fluid in the expansion is critical to prevent the system from high pressure damage

N63 E70 X5 2012
 
#16 · (Edited)
B4_685 said:
Dumb question but you***8217;re not overfilling the coolant are you? With the sealed cooling system, the air pocket above the fluid in the expansion is critical to prevent the system from high pressure damage N63 E70 X5 2012
Click to expand...
No cap overpressure relief? Yep, at 2 Bar.

Checking pressure relief valve in sealing cap: Note:
While the driving at high ambient temperatures, the design may cause the pressure relief valve in the sealing cap to open slightly and air together with dissolved coolant to escape. This coolant vapour condenses on the surface of the expansion tank and leaves traces of coolant when the vehicle has cooled down. These traces of coolant do not indicate whether the sealing cap is defective or not. When the vehicle has been parked up for an extended period of time, the residual escaping coolant can cause the pressure relief valve in the sealing cap to stick; therefore check the sealing cap again 2 to 3 times.
Replace the sealing cap only after you have checked three times and there is an incorrect opening pressure.

Checking pressure relief valve in sealing cap:
Screw sealing cap (1) onto special tool 17 0 114 .

Build up pressure with special tool (hand pump) 17 0 101 ; observe pressure gauge to ascertain when opening pressure is achieved.
Compare opening pressure of pressure relief valve.
 
V
#20 ·
I just went through 3 aftermarket tanks in 2k miles. Bought the new Bmw updated tank that has the yellow arrow and rib splines support all around the tank seams. It***8217;s been great for 1k miles already. Although napa have lifetime warranty, i think i had enough wasting coolant.
 
#23 ·
Do you think 'OEM' is 'from BMW with a BMW label'?

Or are you properly referring to OEM as 'from the same manufacturer that made the BMW OE part'?

Not gonna help, per se, but maybe it will help your shopping diligence.....
 
#25 ·
I doubt you bought a good one. Id stick w something ecs tuning has. Had mine done last year under warty and havent touched it since.
 
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#28 ·
100% they now copy the stickers and apply them. like the hood and trunk ornaments. most are chinese fakes w all the right stamps and dealer tags.
 
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