Is my E46 running too cold ?

[IanDaddy]

Recently I have been monitoring closely the coolant temperature of my M54B25. IIRC, it used to range from about 87 to 97C.

To my surprise, the low point now sometimes go as low as 78C in highway cruising at 120km/h and 80C in heavy traffic.

When I compare the coolant temp (A) at the engine block with the inlet temp (B), I will B go down when A is going up until it reach the high point (A = 97, B = 50)
then the opposite happen until both values are about the same at about 80C. Then the cycle repeats.

I think this is normal behavior when the thermostat opening and closing, it is just that the lower end of the temp is in my opinion too low which is bad for engine efficiency.

My diagnosis is the thermostat is kinda stuck open or close too slowly when the temp drop.

Anyone measure their working temp range of their E46 ? Will appreciate advice.

Thanks

 

[moots]

same engine.
temp at idle at traffic light.
crz will be 92'c.
change your thermostat for peace of mind.cheap insurance.

 

[IanDaddy]

Thanks Moots,

I am making arrangement, will probably do expansion tank and other cooling system component as well.

 

[tckhor]

Moots,
How do you display the engine temperature in the meter cluster ?
Thanks.

 

[moots]

youtube shall show you the way:

https://www.youtube.com/watch?v=JkP0VEgyutw

https://www.youtube.com/watch?v=IB4vtoiFy7c

 

[Ncjing]

My car is same engine, normally hovers around 93-97 in traffic, 90-93 low speed, and 85-95 during cruising, depending on conditions I guess. But 78C to 80C seems abit too low

 

[jarance]

here is my reading using INPA for my M54B25.

 

[IanDaddy]

Thanks Ken and Jarance,
I am convinced that the Thermostat has gone soft. It opens too early and/or can't close properly, if you look at the construction of the housing, the stat may have come a little loose from the 2 plastic tabs which should hold it in properly. Will be get it done ASAP. I can see the consumption is up by at least 10%.

Jarance,

From your INPA readouts, your car is idling and fully warmed up. How is the surrounding/ambient temp was like when the reading was done ? I am asking because my Intake Air temp does not get as high as 66.75C during idle. Thanks

 

[jarance]

ID, the reading was taken in the afternoon. I presume the ambient is about 30degC.

Not sure why the Intake Air Sensor is reading 66degC as compare to 30degC ambient.

 

[IanDaddy]

The IAT sensor is located in the intake manifold, so the air can get a little hot there.

 

[jarance]

The IAT sensor is located in the intake manifold, so the air can get a little hot there.

OIC, it is part of the sensor for the MAF.

 

[IanDaddy]

It is not part of the MAF, it is screwed into a hole somewhere at the top middle of the intake manifold.

IIRC, The M54 in the early E60 it is integrated with the MAF. Not in E46. Part No 3 in this diagram, the hole is between 3rd and 4th runner.

 

[jarance]

OK Got it.. It is hiding near the manifold

http://bmwfans.info/parts-catalog/E46-Sedan/Malaysia/325i-M54/R-N/browse/engine/intake_manifold_system#1739510_3


Looking at the location of the sensor, the temperature around this area is quite high.. 60+degC should be expected.

 

[IanDaddy]

Changing out Intake Air Temp sensor, thermostat, transmission heat exchanger thermostat (half the plastic housing of the stat has disintegrated, wonder where the broken parts are...haizz.), expansion tank and fan clutch.
Hope all these will solve the problem. Will know the answer later tonight.

 

[Mel279]

I have recently replaced my e46 thermostat as my coolant temp just between 60-70 deg which doesn't seem right, after replacing it the temp was about 90 deg which should be the ideal temp.

 

[IanDaddy]

The range is 87 - 96 c now from idling to cruising at 120KMH. If WOT it will drop to 84 momentarily.