Cooling issue

[Spion]

The temperature gauge on my 325i touring is not sticking to the normal halfway point norm. It nudges up near to 3/4 then drops back to sometimes just under half. This has happened in town traffic and motorway driving. There seems to be no reason connected to the way the car is driving.

Any ideas anyone?

[Spion]

bumpity-bump for the at-work crew

[Brianmoooore]

Tighten the small brass nut on the back of the instrument cluster, directly behind the temp. gauge.
Report back if this does not solve the problem.

[Spion]

Tighten the small brass nut on the back of the instrument cluster, directly behind the temp. gauge.
Report back if this does not solve the problem.

Done. Still have overheating issues. Nearly got into the red yesterday and the needle is still up and down a bit.

I have since bled the cooling system via the t'stat bleed screw. No air appears to be present.

I have done the newspaper test on the fan and its stops it when the engine is at idle and very warm. Is the fan coupling f**ked?

Top hose hot, bottom hose cold, FYI

[Brianmoooore]

The fan coupling has no relevance at speed, so if the problem occurs during motorway driving, we can discount it for the moment.
If the gauge needle makes sudden jumps, then it has to be an electrical fault, as the temperature sensor can only respond relatively slowly, even if there were sudden changes in the coolant temperature.
Otherwise, a new thermostat has to be the next thing to try.

[Spion]

The fan coupling has no relevance at speed, so if the problem occurs during motorway driving, we can discount it for the moment.
If the gauge needle makes sudden jumps, then it has to be an electrical fault, as the temperature sensor can only respond relatively slowly, even if there were sudden changes in the coolant temperature.
Otherwise, a new thermostat has to be the next thing to try.

Well, there's no sudden movement of the temp gauge needle. It's quite slow. During m'way driving it'll go up to near 3/4, spend a lot of time between 1/2 and 3/4 and sometimes drop back to just under 1/2.

I spend a lot of time driving 70-100 miles on m'ways so that's tolerable. But, it is in town that it worries me. I got caught in a jam in a rare spell in town the other day and it nearly got into the red. So, the tendency is for it to overheat.

Thermostat then? Why would it be that? Is it possibly behaving erratically?

[ucpsale]

Sounds to me like the viscus fan coupling is faulty, don't buy a secound hand one.

[Brianmoooore]

Overheating in traffic/town driving only is most likely caused by a duff viscous coupling. Overheating when driving normally is not.
I'd change the thermostat next, because that's the device that sets the engine running temperature.

[Spion]

Overheating in traffic/town driving only is most likely caused by a duff viscous coupling. Overheating when driving normally is not.

Overheating in town traffic IS what's happening, so am I better to go for the viscous coupling first?

[Brianmoooore]

This has happened in town traffic and motorway driving.

[Spion]

This has happened in town traffic and motorway driving.

Yep. I said that on Oct 12th.

At that point I hadn't got caught in a traffic jam. A few days ago I did, and this is what I said on Oct 23 . . . .

During m'way driving it'll go up to near 3/4, spend a lot of time between 1/2 and 3/4 and sometimes drop back to just under 1/2.

I spend a lot of time driving 70-100 miles on m'ways so that's tolerable. But, it is in town that it worries me. I got caught in a jam in a rare spell in town the other day and it nearly got into the red. So, the tendency is for it to overheat.

Fan coupling then?

[Fushion_Julz]

Could be the water pump impeller wearing out....

I'd do as Brian suggests and change the 'stat first, but if the top rad hose is hot, I'd say it was working OK...

The pump just sounds a bit down on efficiency...

[kman82]

I had problems with mine overheating recently. Top hose hot bottom cold. First i changed the thermostat, if the top hose is hot though it sounds like yours is working. With the newspaper test there was no resistance on the fan so i had that changed and the problem was solved.