N54 - Coolant Pressure Release Valve

Hamster93 · 01-19-2021, 04:30 AM

Hi gents.

Got my water pump cracked recently. We say it could be many reasons. Oil was also coming in (oil gaskets ordered) Just want to make sure does N54 coolant system has some kind of release valve. I believe we running 1-2 bar so 4-6 bar oil pressure leaking in could be a problem if there is no release valve?

Thanks guys. AK

JonOhh · 01-19-2021, 08:06 AM

It's built into the cap, but I can't remember the pressure. It should be labeled on the colored section in the middle of the inside of the cap, though.

aarons1 · 01-20-2021, 05:10 PM

the cap

Hamster93 · 01-21-2021, 06:00 AM

Cheers mate. Very helpful. It says 140 at the bottom. Guess it is in kPa as it equates to 1.4 bar.

Anyone knows where it dispose its overpressured fluid to? My old Toyota has a radiator cap and it connects to the surge tank then to the disposal hose to the ground. Don't see that in our reservoir. Could it be messy in the engine compartment when it's overpressured?

TunafishE93 · 01-21-2021, 06:41 AM

It has a little hole in the expansion tank that goes under the tank.

Hamster93 · 01-22-2021, 11:58 PM

Cheers mate. I think it's just a drain hole for spill coolant. Wonder it should have some kind of drain hose from the bottom of the reservoir to the ground as BMW would love to make things neat and tidy.

When the overpressured fume come out it is likely to be all over the place as I can't see any seal on the cap's rim. Correct me if I'm wrong.

TunafishE93 · 01-23-2021, 12:56 AM

Theres not a seal but the cap vents up top which will hit the side walls of the cap. This will route the fluid down into the expansion tanks overflow hole. The expansion tank also has walls that go up. If enough fluid it leaking out then yes it could get all over but it would have to overwhelm the overflow hole first. Likely if you have a mess in your engine its a leaking expansion tank not cap.

Hamster93 · 01-23-2021, 02:47 PM

Cheers mate. It now seemed to work out like you said. Nothing messy. Last time it started as a bottom hose of the reservoir that came off. That was all over the place. Then left it idle for long time the water pump cracked. I dont know if I tightened the vent screw too much or not but the o-ring was not there (it used to) and that's again all over the place. This time I believe it vented out from the cap through the bottom just like you said. Oil gaskets arrived today hope this will cure. Creamy coolant clogged up so much this time (have just bled and sucked out yesterday) the return hose to the reservoir didn't put through the water any more in the bleeding procedure.

01-19-2021, 04:30 AM	#1
Hamster93 Enlisted Member 3 Rep 46 Posts Drives: E93 335i Join Date: Apr 2020 Location: 16N 103E iTrader: (0)	N54 - Coolant Pressure Release Valve - Is there Any? Hi gents. Got my water pump cracked recently. We say it could be many reasons. Oil was also coming in (oil gaskets ordered) Just want to make sure does N54 coolant system has some kind of release valve. I believe we running 1-2 bar so 4-6 bar oil pressure leaking in could be a problem if there is no release valve? Thanks guys. AK __________________ Project E36 Project E93
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01-19-2021, 08:06 AM	#2
JonOhh Captain 672 Rep 733 Posts Drives: 06' 330i Join Date: Dec 2019 Location: Tuscaloosa, Alabama iTrader: (0) Garage List 1999 BMW M3 [10.00] 2013 Fiat 500c Abarth [0.00] 1985 Fiat/Bertone X1/9 [0.00] 2006 BMW 330i [0.00]	It's built into the cap, but I can't remember the pressure. It should be labeled on the colored section in the middle of the inside of the cap, though.
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01-20-2021, 05:10 PM	#3
aarons1 Registered 0 Rep 1 Posts Drives: 07 335i e92 Join Date: Jan 2021 Location: OKC iTrader: (0) Garage List 2007 335i [0.00]	the cap
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01-21-2021, 06:00 AM	#4
Hamster93 Enlisted Member 3 Rep 46 Posts Drives: E93 335i Join Date: Apr 2020 Location: 16N 103E iTrader: (0)	Cheers mate. Very helpful. It says 140 at the bottom. Guess it is in kPa as it equates to 1.4 bar. Anyone knows where it dispose its overpressured fluid to? My old Toyota has a radiator cap and it connects to the surge tank then to the disposal hose to the ground. Don't see that in our reservoir. Could it be messy in the engine compartment when it's overpressured?
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01-21-2021, 06:41 AM	#5
TunafishE93 Major 418 Rep 1,154 Posts Drives: BMW 335i Join Date: Dec 2019 Location: NV iTrader: (0)	It has a little hole in the expansion tank that goes under the tank. Attached Images
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01-22-2021, 11:58 PM	#6
Hamster93 Enlisted Member 3 Rep 46 Posts Drives: E93 335i Join Date: Apr 2020 Location: 16N 103E iTrader: (0)	Cheers mate. I think it's just a drain hole for spill coolant. Wonder it should have some kind of drain hose from the bottom of the reservoir to the ground as BMW would love to make things neat and tidy. When the overpressured fume come out it is likely to be all over the place as I can't see any seal on the cap's rim. Correct me if I'm wrong.
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01-23-2021, 12:56 AM	#7
TunafishE93 Major 418 Rep 1,154 Posts Drives: BMW 335i Join Date: Dec 2019 Location: NV iTrader: (0)	Theres not a seal but the cap vents up top which will hit the side walls of the cap. This will route the fluid down into the expansion tanks overflow hole. The expansion tank also has walls that go up. If enough fluid it leaking out then yes it could get all over but it would have to overwhelm the overflow hole first. Likely if you have a mess in your engine its a leaking expansion tank not cap.
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01-23-2021, 02:47 PM	#8
Hamster93 Enlisted Member 3 Rep 46 Posts Drives: E93 335i Join Date: Apr 2020 Location: 16N 103E iTrader: (0)	Cheers mate. It now seemed to work out like you said. Nothing messy. Last time it started as a bottom hose of the reservoir that came off. That was all over the place. Then left it idle for long time the water pump cracked. I dont know if I tightened the vent screw too much or not but the o-ring was not there (it used to) and that's again all over the place. This time I believe it vented out from the cap through the bottom just like you said. Oil gaskets arrived today hope this will cure. Creamy coolant clogged up so much this time (have just bled and sucked out yesterday) the return hose to the reservoir didn't put through the water any more in the bleeding procedure.
	Appreciate 0 Quote