BMW Forums : BimmerForums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
Hi everyone,

My wife's 2004 E83, with M54 (3.0i) engine has an odd cooling problem that I can't get to the bottom of. I've got to the end of my diagnostic tether with this one, so am wondering if the collective brain can help.

When the engine gets warm enough to activate the fan, everything is fine for about 20 mins. Fan runs as normal, i.e. on and off. Rad is warm, bottom hose is warm etc. Then for some reason the fan seems to get 'stuck' on high and runs all the time on high. The result is that it cools the rad so much, the rad bottom hose runs cold.

Looking at the OBC hidden dash menu, the engine temp fluctuates between 97-101 deg C when everything is ok and I can see the fan kicking in at about 99 bringing the templ back down. Once the fan starts to run on high permanently, the OBC dash engine temp sits at 99 like it's pegged there, occasionally hitting 98 or 100, but mostly 99 deg C.

INPA doesn't show me any stored errors, and the engine doesn't overheat at all. INPA analogue display tells me the engine temp is about 99 and the coolant outlet temp drops to something like 25-30 deg C when the fan runs like this. When the fan is behaving, the engine temp hovers around 99, and the coolant anywhere from 86-99 deg C too.

Also, i've noticed that when in traffic, and when the fan is always on, and the OBC temp sits at 99 on the dash. But when I get to open road and floor it, the OBC temp drops anywhere down to 80-90 degC before coming back up to 97-99, like it's getting an influx of cold water from the rad.

Now, I know what you're thinking. New thermostat and water pump, right? But I've already changed both of them for OEM replacements, and I've changed the bottom hose temp sensor too, for a genuine parts replacement. Radiator and coolant are new too. This problem was happening before I changed the pump and t'stat too, as I thought the t'stat was sticking but perhaps not.

So you can see how I'm at the end of my tether. Searching and googling the symptoms always points to new pump and stat, which isn't the case here.

I'm left wondering if this is a software bug now.

Any ideas or help would be gratefully received.

Cheers
Dobbs...
2004 X3 3.0i Sport (E83 M54)
 

·
Registered
Joined
·
330 Posts
The temp. dropping when you floor it is normal. It's the electrically controlled thermostat's way of ensuring the engine doesn't ping under high load.

The only thing I can think of is the the oil temperature sensor. If that is reading too high then the engine might be running the fan to indirectly cool the oil. Some diagnostic can read the output from the oil sensor, not all though. INPA and DIS can probably do it though, or even perhaps a C110 handheld reader (cheap).
 

·
Registered
Joined
·
5 Posts
Discussion Starter #4
How about a sticking fan relay?
Apparently the fan doesn't have one, it's got an ecu on the fan body to control itself. Then again, the fan in only a few years old as the other one died when the expansion tank exploded all over it.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #5
The temp. dropping when you floor it is normal. It's the electrically controlled thermostat's way of ensuring the engine doesn't ping under high load.

The only thing I can think of is the the oil temperature sensor. If that is reading too high then the engine might be running the fan to indirectly cool the oil. Some diagnostic can read the output from the oil sensor, not all though. INPA and DIS can probably do it though, or even perhaps a C110 handheld reader (cheap).
I did wonder that, and it's the only sensor in the whole setup I haven't replaced yet. Apart from the AC pressure sensor, which is also under suspicion now.

Attached screen shot shows oil within limits in INPA though.

engine-temps.jpg
 
1 - 5 of 5 Posts
Top