Coolant Alert: Leaky Expansion Tank

[NYBulldog]

This happen to anyone? Seems like an odd thing to require replacement. Just curious.

Right at the cutting line of my expansion tank showed slow leaking. It had white residue and missing about a Quart of coolant.

I had a new Expansion Tank installed.

I was mostly concerned with damage to the Alternator. Fingers crossed its just fine.

[EB89]

This is extremely common on the E9X platform, the coolant expansion tank cracking along the plastic weld line like you are seeing.

I had it myself.

I’m surprised this has made its way into the F8X platform.

Your alternator should be ok, you could use some distilled water to wash any coolant off it with the battery unplugged and and air blower rot fmget it completely dry.

[Poiseuille]

Replaced six expansion tanks in the 540i I drove for 17 years. Replaced the expansion tank in my Z3 twice.....you see the pattern developing here. Factory sources these tanks from whomever has the low bid. On E39 forums expansion tanks generate endless threads. Have to say though there hasn't been much expansion tank chatter on this forum.
Some advice though: never ever overfill that tank, don't add coolant when the motor is warm.

[Fast4d]

108k and 13 years on my E90 325. still original WP and everything else except coils and starter. replacement WP sitting in my garage waiting. I'm lazy and tempted to see how long it'll last.

couple other BMW V8s we've had. not so lucky....

[tom @ eas]

Seen this a couple of times. Looks like the failure point where the cap is bonded to the tank. Similar failures have happened on chargepipes in the past:





Luckily it isn't common and should be covered under warranty.

[tom @ eas]

Originally Posted by Poiseuille

Replaced six expansion tanks in the 540i I drove for 17 years. Replaced the expansion tank in my Z3 twice.....you see the pattern developing here. Factory sources these tanks from whomever has the low bid. On E39 forums expansion tanks generate endless threads. Have to say though there hasn't been much expansion tank chatter on this forum.
Some advice though: never ever overfill that tank, don't add coolant when the motor is warm.

The e39 tanks were ticking time bombs, I've seen holes in the hood from the tanks exploding.

[Poiseuille]

Originally Posted by Fast4d

108k and 13 years on my E90 325. still original WP and everything else except coils and starter. replacement WP sitting in my garage waiting. I'm lazy and tempted to see how long it'll last.

couple other BMW V8s we've had. not so lucky....

The original WP complete with plastic impeller? Well, yer braver than me Fast. So when you finally do replace that thing how about posting a pic of the impeller in here?

[climax_e92]

Originally Posted by NYBulldog

This happen to anyone? Seems like an odd thing to require replacement. Just curious.

Right at the cutting line of my expansion tank showed slow leaking. It had white residue and missing about a Quart of coolant.

I had a new Expansion Tank installed.

I was mostly concerned with damage to the Alternator. Fingers crossed its just fine.

My gf has the same problem with her 15 m3. Just bought an expansion tank from the dealer and going to replace when it arrives. How hard was the install? Is it just the 1 hose ontop of the reservoir? Thank you

[Alpine_F82]

So I replaced my expansion tank today because it was leaking. So I replaced it, and today after the first drive, it is leaking out the same spots again so al that for nothing does anybody have may input. I also thought this may be why my car is hotter than usual, it stays around 235 which when I bought the car it stays at 210-220 in efficient now it’s 230-240. I haven’t had it 210’s-220’s standard in probably a year, which bugs me.

[Poiseuille]

Originally Posted by M4BimmerChris

So I replaced my expansion tank today because it was leaking. So I replaced it, and today after the first drive, it is leaking out the same spots again so al that for nothing does anybody have may input. I also thought this may be why my car is hotter than usual, it stays around 235 which when I bought the car it stays at 210-220 in efficient now it's 230-240.

yeah, that's pretty irritating, happened to me once (M52TU). noted the leak next day and it was a random hairline crack NOT on a seam so probably manufacturing defect. who knows?
other tank failures I've had remain unsolved. longest-lived tank lasted 72K miles but I've had others that didn't make 8K miles.
idkw these tanks have been such a problem for so many years and in my experience the issue is the same for both OEM and aftermarket tanks.

regarding your temp readings: I've never noted increased engine temps during exp tank leakage, but then I've never let one go very long. also (and probably related) every failed tank I've had passed a pressure test.

[Blancofire]

Is there any tutorial on how to replace the expansion tank??

[drreid3]

I've read in Mike Miller's "Lifetime Maintenance Schedule" v3.13 on page 24, to fill the coolant to the MINIMUM fill level to avoid issues with coolant expansion tanks.

[ss-f82]

Originally Posted by NYBulldog

This happen to anyone? Seems like an odd thing to require replacement. Just curious.

Right at the cutting line of my expansion tank showed slow leaking. It had white residue and missing about a Quart of coolant.

I had a new Expansion Tank installed.

I was mostly concerned with damage to the Alternator. Fingers crossed its just fine.

Does anybody know where i can buy that gold screw in the picture..?

[sharpmoney]

nothing from the idrive system.

[N1rve]

Originally Posted by sharpmoney

nothing from the idrive system.

Isn't that the top mounted intercooler?