N55 coolant expansion tank leak

christofis135i · 09-20-2018, 06:40 PM

Today while driving home from work I got a "low coolant" light on my dash. Got home, popped the hood and started checking everywhere. I noticed a puddle forming on the ground by the the front bumper/RF tire.

I ended up finding a rather large leak on the bottom of the expansion tank (circled in photo below)

Has anyone else seen this? My guess is either the hose is lose or the expansion tank is cracked somewhere in that area where it meets the hose. ECS sells new tanks for $115.33. I'm not sure what hose is on the bottom of the tank.

MightyMouseTech · 09-20-2018, 07:19 PM

Very, very common. Replace tank, enjoy driving till it cracks again.

shawnyeeah · 09-23-2018, 09:27 PM

Happened to me at 80K miles. Also keep in mind the N55 tank is different from the N54 tank if you plan on sourcing the parts

christofis135i · 09-24-2018, 10:11 AM

Wasn't cracked 🙃 just a broken bleeder screw, thank god. Ordered the ecs aluminum one.

Olgeezer1 · 09-29-2018, 04:09 PM

Just an old timer's tip to at least hopefully extend expansion tank life. Keep coolant level at the Minimum mark ( where the float is just even with tank opening). This allows actual room for expansion and has absolutely no effect on operating temps., as verified by my permanently connected Scan Gauge. This will mean siphoning off the excess after every service as well intentioned techs. constantly overfill.

juld0zer · 10-14-2018, 06:28 AM

The plastic just ages and the bonded seam fails also. My N55 went through 3 in its 8yr life. All three blew at the seam.

I'd say the plastic doesn't tolerate vibration well and the mounting method provides insufficient protection.

jonsno · 10-18-2018, 02:04 PM

while i didnt get a warning for low coolant or anything an underhood inspection I saw dried up marks all around my coolant tank which must mean that i have a leak somewhere.. I just ordered another tank from FCP Euro but how would i tell if its just a simple screw like yours was?

christofis135i · 10-20-2018, 07:00 PM

Quote:

Originally Posted by jonsno

while i didnt get a warning for low coolant or anything an underhood inspection I saw dried up marks all around my coolant tank which must mean that i have a leak somewhere.. I just ordered another tank from FCP Euro but how would i tell if its just a simple screw like yours was?

Tried to loosen the bleeder screw and the head fell off lol

09-20-2018, 06:40 PM	#1
christofis135i Banned 235 Rep 277 Posts Drives: 2011 135i White/Red Join Date: Jul 2017 Location: Michigan iTrader: (0)	N55 coolant expansion tank leak Today while driving home from work I got a "low coolant" light on my dash. Got home, popped the hood and started checking everywhere. I noticed a puddle forming on the ground by the the front bumper/RF tire. I ended up finding a rather large leak on the bottom of the expansion tank (circled in photo below) Has anyone else seen this? My guess is either the hose is lose or the expansion tank is cracked somewhere in that area where it meets the hose. ECS sells new tanks for $115.33. I'm not sure what hose is on the bottom of the tank. Attached Images
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09-20-2018, 07:19 PM	#2
MightyMouseTech Major General 4338 Rep 6,196 Posts Drives: 13 135i 6MT LeMans Blue MSport Join Date: Feb 2013 Location: Ottawa, Canada iTrader: (0)	Very, very common. Replace tank, enjoy driving till it cracks again.
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09-23-2018, 09:27 PM	#3
shawnyeeah Private First Class 20 Rep 103 Posts Drives: '12 N55 135i Join Date: Feb 2016 Location: Atlanta, GA iTrader: (1)	Happened to me at 80K miles. Also keep in mind the N55 tank is different from the N54 tank if you plan on sourcing the parts
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09-24-2018, 10:11 AM	#4
christofis135i Banned 235 Rep 277 Posts Drives: 2011 135i White/Red Join Date: Jul 2017 Location: Michigan iTrader: (0)	Wasn't cracked 🙃 just a broken bleeder screw, thank god. Ordered the ecs aluminum one.
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09-29-2018, 04:09 PM	#5
Olgeezer1 Lieutenant 177 Rep 502 Posts Drives: 2010 128i 6MT Sport Pkg. 18" Join Date: Jul 2013 Location: Ottawa, Canada iTrader: (0) Garage List 2010 E82 128i N52 [0.00]	Just an old timer's tip to at least hopefully extend expansion tank life. Keep coolant level at the Minimum mark ( where the float is just even with tank opening). This allows actual room for expansion and has absolutely no effect on operating temps., as verified by my permanently connected Scan Gauge. This will mean siphoning off the excess after every service as well intentioned techs. constantly overfill.
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10-14-2018, 06:28 AM	#6
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	The plastic just ages and the bonded seam fails also. My N55 went through 3 in its 8yr life. All three blew at the seam. I'd say the plastic doesn't tolerate vibration well and the mounting method provides insufficient protection.
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10-18-2018, 02:04 PM	#7
jonsno New Member 0 Rep 12 Posts Drives: 2013 135i Join Date: May 2018 Location: Port Orange FL iTrader: (0)	while i didnt get a warning for low coolant or anything an underhood inspection I saw dried up marks all around my coolant tank which must mean that i have a leak somewhere.. I just ordered another tank from FCP Euro but how would i tell if its just a simple screw like yours was?
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