Coolant issue coming out of storage

SpectreMech · 04-24-2022, 05:28 PM

2011 Z4 35is has been sitting for three months in a storage unit. Cranked right up, and I very slowly and carefully brought it up to temp before going for a good battery charge ride.

Everything was great, temp needle reached just below 250, no warning lights or issues at all. Pull back into storage, and five minutes later I see steam coming up around the front right wheel. Look under the car, and there's a small, but steady stream of coolant venting.

Opened the hood, and there's a four inch geyser of coolant coming up from the top front of the expansion tank where a small hose connects...presumably off the radiator. It's not the hose, it looks like a small pressure relief opening on the tank itself right where the hose connects. Stops in three minutes, probably lost a cup or two of fluid total. Car never overheated, I backed it up to clean up the mess...still no idiot lights or warnings. Edit: Found a pic of the tank, and did a crude arrow to the geyser point. I think that cross-point cover is gone...Did I pop a pressure relief button?

Any ideas? Oil was serviced in Nov, no idea if they topped off the other fluids. Gave it one last drive in Dec before it went into hibernation.

Second edit: it's coming from the bleed screw, and I think mine is gone. Hopefully it just vibrated out...

SpectreMech · 04-25-2022, 08:03 PM

Repaired! Got a headlamp over to storage and discovered the entire head had fractured and fallen off, leaving the exposed vent channel. Auto Zone actually had the correct (Chinese, but...there were two in the pack, so the spare goes in the glove) screw, the issue was getting the remaining screw (threaded shank) out of the reservoir without damaging it's threads. It broke off about 1/8" down...nothing to grab.

Used a hand torch to heat the blade of skinny straight blade screwdriver very hot, and carefully sank it into the center of the screw shank. Let it cool for a minute or two, and it broke loose and easily rotated out. If you could see at all from this very fuzzy photo in the original post, the screw actually fractured up fairly close to the head. Reserviced the reservoir, and just returned from a successful op check. Total cost...$5 bleed screw and $2 bottle of distilled water.

MarinerZ4C · 04-26-2022, 03:01 PM

Great that you got it fixed - and this could happen to quite a few other BMW's. Thanks for updating your fix.

04-24-2022, 05:28 PM	#1
SpectreMech Private 7 Rep 87 Posts Drives: 2011 Z4 iDrive 35is Join Date: Dec 2007 Location: BF Idaho iTrader: (0)	Coolant issue coming out of storage 2011 Z4 35is has been sitting for three months in a storage unit. Cranked right up, and I very slowly and carefully brought it up to temp before going for a good battery charge ride. Everything was great, temp needle reached just below 250, no warning lights or issues at all. Pull back into storage, and five minutes later I see steam coming up around the front right wheel. Look under the car, and there's a small, but steady stream of coolant venting. Opened the hood, and there's a four inch geyser of coolant coming up from the top front of the expansion tank where a small hose connects...presumably off the radiator. It's not the hose, it looks like a small pressure relief opening on the tank itself right where the hose connects. Stops in three minutes, probably lost a cup or two of fluid total. Car never overheated, I backed it up to clean up the mess...still no idiot lights or warnings. Edit: Found a pic of the tank, and did a crude arrow to the geyser point. I think that cross-point cover is gone...Did I pop a pressure relief button? Any ideas? Oil was serviced in Nov, no idea if they topped off the other fluids. Gave it one last drive in Dec before it went into hibernation. Second edit: it's coming from the bleed screw, and I think mine is gone. Hopefully it just vibrated out... Attached Images Last edited by SpectreMech; 04-25-2022 at 08:05 PM.. Reason: Repaired
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04-25-2022, 08:03 PM	#2
SpectreMech Private 7 Rep 87 Posts Drives: 2011 Z4 iDrive 35is Join Date: Dec 2007 Location: BF Idaho iTrader: (0)	Repaired! Got a headlamp over to storage and discovered the entire head had fractured and fallen off, leaving the exposed vent channel. Auto Zone actually had the correct (Chinese, but...there were two in the pack, so the spare goes in the glove) screw, the issue was getting the remaining screw (threaded shank) out of the reservoir without damaging it's threads. It broke off about 1/8" down...nothing to grab. Used a hand torch to heat the blade of skinny straight blade screwdriver very hot, and carefully sank it into the center of the screw shank. Let it cool for a minute or two, and it broke loose and easily rotated out. If you could see at all from this very fuzzy photo in the original post, the screw actually fractured up fairly close to the head. Reserviced the reservoir, and just returned from a successful op check. Total cost...$5 bleed screw and $2 bottle of distilled water.
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04-26-2022, 03:01 PM	#3
MarinerZ4C Enlisted Member 43 Rep 47 Posts Drives: 2006 BMW Z4 3.0Si Coupe Join Date: Mar 2021 Location: Minnesota iTrader: (0)	Great that you got it fixed - and this could happen to quite a few other BMW's. Thanks for updating your fix.
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