N52 Coolant temps drop when idling

Zaeres · 08-07-2024, 03:56 AM

Hello everyone!

Since a few months ago I've noticed something weird going on with my coolant temps. The issue is that while I'm driving (city, highway etc.) the coolant temps are spot on (~105 while driving normally, ~110 in the city in traffic, drops below 90 when I drive more aggressively). However if the car stays at idle for a few minutes, usually around 5, the fan kicks in, water pump mode goes from 2 to 5 (according to bimmerlink), water pump speed goes from ~45 to 117 and the temps start dropping to around 77 degrees C.

I've also noticed that the moment this starts happening, the car also starts shaking a little bit. The temperatures won't normalize until I shut the car off and it stays off for awhile, maybe a few hours will do. The car is at 106k KM, water pump and thermostat were OEM but I've decided to change them due to finding discussions online that this is a sign the water pump is dying. Changed pump with Pierburg and thermostat with Mahle, same deal, absolutely no difference. I've tried not turning on the AC while driving to see if that might be causing the issue, same deal.

I haven't done anything to the software, even updating it. I will be updating it in the next few weeks, however I'm worried that might not fix this issue. Has anyone else come across this problem? The car is a 2006 BMW E92 325i with the N52B52 engine. Thank you guys for any suggestions in advance!

The Nightman · 08-23-2024, 11:13 AM

Any fault codes? Radiator fan working?

Zaeres · 09-04-2024, 03:10 AM

Quote:

Originally Posted by The Nightman

Any fault codes? Radiator fan working?

No fault codes, fan is running even with AC off when this happens.

ptpending · 09-04-2024, 05:50 AM

check the thermostat, by checking the pipes to and from radiator
when temperature fall below 90 it should close, so return pipe from radiator will not circuilate
yo might have damaged or not working themostat heating circuit or connector
when pump dies, or thermostat, sometimes during replacement it can be damaged
use infrared termometer to get temp trends on different pipes
you may also monitor in app or in bmw software the tempersture of coolant coming to salon heater

08-07-2024, 03:56 AM	#1
Zaeres Registered 0 Rep 4 Posts Drives: BMW E92 325i, Peugeot 306 1.8 Join Date: Aug 2024 Location: Bulgaria iTrader: (0)	N52 Coolant temps drop when idling Hello everyone! Since a few months ago I've noticed something weird going on with my coolant temps. The issue is that while I'm driving (city, highway etc.) the coolant temps are spot on (~105 while driving normally, ~110 in the city in traffic, drops below 90 when I drive more aggressively). However if the car stays at idle for a few minutes, usually around 5, the fan kicks in, water pump mode goes from 2 to 5 (according to bimmerlink), water pump speed goes from ~45 to 117 and the temps start dropping to around 77 degrees C. I've also noticed that the moment this starts happening, the car also starts shaking a little bit. The temperatures won't normalize until I shut the car off and it stays off for awhile, maybe a few hours will do. The car is at 106k KM, water pump and thermostat were OEM but I've decided to change them due to finding discussions online that this is a sign the water pump is dying. Changed pump with Pierburg and thermostat with Mahle, same deal, absolutely no difference. I've tried not turning on the AC while driving to see if that might be causing the issue, same deal. I haven't done anything to the software, even updating it. I will be updating it in the next few weeks, however I'm worried that might not fix this issue. Has anyone else come across this problem? The car is a 2006 BMW E92 325i with the N52B52 engine. Thank you guys for any suggestions in advance! Last edited by Zaeres; 08-07-2024 at 04:11 AM..
	Appreciate 0 Tweet Quote

08-23-2024, 11:13 AM	#2
The Nightman Cometh 1216 Rep 1,389 Posts Drives: Boy's Soul Join Date: Jul 2016 Location: Boy's Hole iTrader: (4) Garage List E90 LCI "330i& ... [10.00]	Any fault codes? Radiator fan working?
	Appreciate 0 Quote

09-04-2024, 05:50 AM	#4
ptpending Colonel 514 Rep 2,887 Posts Drives: e81 Join Date: Dec 2013 Location: Poland iTrader: (1)	check the thermostat, by checking the pipes to and from radiator when temperature fall below 90 it should close, so return pipe from radiator will not circuilate yo might have damaged or not working themostat heating circuit or connector when pump dies, or thermostat, sometimes during replacement it can be damaged use infrared termometer to get temp trends on different pipes you may also monitor in app or in bmw software the tempersture of coolant coming to salon heater __________________ E81 2007 130i 6cylinder Montego blue Retrofits: Harman Kardon, High-beam assistant, Removable tow hitch. Auto-dim folding exterior mirrors. Lumbar support. Perfomance Brakes.
	Appreciate 0 Quote