N54 steam escape incident after stopping - small or big problem or just stupidity?

[xQx]

So, I live on a residential street with speedhumps, which on the way home from work generally means multiple second-gear pulls right before turning the car off.

Last night I did the usual thing, and had the JB4 on so I know what the temps were when stopping: Oil 110C, Coolant: 100C, IAT: 15C above ambient (Absolute about 45C)

About 2 minutes after stopping, the car started bellowing steam out of the left hand side, which appeared to be coming either from the coolant overflow line back to the reservoir or somewhere at the top of the radiator. The car didn't sound like it was boiling (I've boiled older cars before, you can hear the radiator hose bubbling like a kettle) - it seemed more like the coolant system in an N54 is kept under considerable pressure, and it sprung a leak. 100C is boiling point for pure water, but well below boiling point for engine coolant solution - of course, turning the car off stopped the water from circulating, so it's entirely possible some sections were well above boiling.

I've waited for the car to cool, and it took 2.5 litres of water to bring it back to full. Idling the car seems to be normal now, water temps rise as normal proportionally to the oil temp, and there's no sign of leaks, splits or loose clamps.

I've removed the factory air diverter from the front grille to the DCI (or factory airbox), because the leak was below that. I was planning on taking the car for another drive to get it up to temperature and (while trying not to burn myself) see exactly where it's blowing steam from.

But I thought I'd ask here first - any common problems with the N54 I should know about?

Or was I an idiot and should I be idling the car down to a reasonable temperature before turning it off (like the old days with a turbo timer)?

[1and1]

Our system will allow the electric water pump to run for a few minutes after shutting down to help address such things- a distinct improvement over basic mechanical pumps. As for turbo cooling, turbos cooled with both water and oil typically don't really need the turbo-timer treatment as the water cooling process is enough to keep the oil from coking in the CHRA- cycling oil only cooled turbos till the oil till it cools enough to prevent that was the reason for timers to begin with.

That said, you typically want to take it easy the last mile or so before shutting down to prevent extremes. Really, to cause problems you'd need to come screaming into your parking spot hard on it & sideways fast & furious style to cause issues, but since you describe "...multiple second-gear pulls right before turning the car off..." you're not too far from that mark.

[Mr Rooty Von Tooty]

The cooling system is losing water. The engine overheated due to the loss of water. The first place I'd look is the radiator. I'd pull it and have it rebuilt or cleaned out. Next I'd replace the main hoses and possibly the thermostat. Finally, I'd check on all the hose connection on the electric water pump.

[Matticus91]

When you say "left", do you mean driver side or pass side?

[xQx]

Originally Posted by Matticus91

When you say "left", do you mean driver side or pass side?

I'm in Australia, so it's passenger side.

If it were a US delivered car - it'd be drivers side

The opposite side to the turbos.

[Matticus91]

Originally Posted by xQx

I'm in Australia, so it's passenger side.

If it were a US delivered car - it'd be drivers side

The opposite side to the turbos.

Oy sorry I missed that, but ok I wanted to make sure we were on the same "side" (pun intended) because there's no valves on the left side, they're on the right side. Might want to look for leaks!

[STR8-6IX]

multiple second gear pulls before turning it off?

what are you doing? thats exactly what you SHOULDNT be doing when you plan to turn the car off in a couple minutes. you're boiling the shit out of your coolant and pressurizing the cooling system which is no good for the car. stop being a fucking moron and drive in cool down mode for the like 5-10 min of your drive..

[xQx]

Hey Everyone,

Thanks very much for your advice above. I'll give the car time to cool down while running/driving in future. It'll be nice if this was just a warning...

I had heard you no longer needed to worry about the health of the turbos after hard driving because they'd redesigned the cooling system in the late 90's (thus negating the need for turbo timers) - but this sort of thing highlights:
a) Just because you can drive modern cars without warming them up or cooling them down (don't worry, I warm up the car) - doesn't mean you should.
b) My 'enthusiastic driving' is actually what probably what normal people (and OEM warranty departments) would call "abuse".

Anyway, I was reading through chadillac2000's build thread and he mentioned a particular hose failed in his previous car. I went for a short gentle drive over Easter to (carefully) get the car up to 'pressure', and found this hose had split:



Upon removal I found it was severely degraded - so hopefully the failure was due to the physical pressure of the OEM cold-air intake which is no longer supported by the OEM airbox due to my DCI, rather than by excess coolant pressure.

Time will tell.

[STR8-6IX]

Originally Posted by xQx

Hey Everyone,

Thanks very much for your advice above. I'll give the car time to cool down while running/driving in future. It'll be nice if this was just a warning...

I had heard you no longer needed to worry about the health of the turbos after hard driving because they'd redesigned the cooling system in the late 90's (thus negating the need for turbo timers) - but this sort of thing highlights:
a) Just because you can drive modern cars without warming them up or cooling them down (don't worry, I warm up the car) - doesn't mean you should.
b) My 'enthusiastic driving' is actually what probably what normal people (and OEM warranty departments) would call "abuse".

Anyway, I was reading through chadillac2000's build thread and he mentioned a particular hose failed in his previous car. I went for a short gentle drive over Easter to (carefully) get the car up to 'pressure', and found this hose had split:



Upon removal I found it was severely degraded - so hopefully the failure was due to the physical pressure of the OEM cold-air intake which is no longer supported by the OEM airbox due to my DCI, rather than by excess coolant pressure.

Time will tell.

just dont drive aggressively for the last 10 minutes before parking... not a good idea. at the very least crank up your heater 5 minutes before you park so your pump isnt circulating boiling hot coolant once the engine is shut off.

[1and1]

Originally Posted by STR8-6IX

just dont drive aggressively for the last 10 minutes before parking... not a good idea. at the very least crank up your heater 5 minutes before you park so your pump isnt circulating boiling hot coolant once the engine is shut off.

Would work, but much less sweat inducing to just drive easily for a bit before shutting down