325i 1989 weird temp behaviour, please help troubleshoot

[madmax2]

hi people, my 325i e30 has slowly started to go spooky on me with regard to the behaviour of the coolant temperature.

The gauge will sit about one needles width above halfway during normal driving, heater blows warm etc...viscous fan is behaving and thermostat is opening correctly (checked temperature of top and bottom hoses while cold and again when hot) coolant level is perfecto and water pump works.

but, when i turn the engine off, and then put the key to access1 position, after about 10 minutes you can see the temp gauge has moved up to 3/4 position...this is a new development...I have owned the car for 4 years and know her habits:-)

Can anybody suggest why this is happening? The temp gauge would be rock solid at half for the last few years once warmed up, but beginning this week it is now at just above half when under normal conditions, with the second symptom being the temp gauge showing the engine getting hotter once it is switched off.

If I switch the car on when the gauge is at 3/4 it takes aroun 5 seconds to return to just above half...almost as if the water pump is now circulating the coolant again and she is happy. I have never in my life heard of a car getting hotter when switched off... please help, I would love for her to be 100% again.

cheers

[Brianmoooore]

Sorry mate, but it's perfectly normal for a car to get hotter immediately after it's switched off. It's called heat soak, and happens on all cars, E30s included, except a few that have auxillary electric water pumps.
If you temp gauge position has changed recently, then the first thing to do is take out the instrunent cluster and tighten a small nut on the back, immediately behind the temp gauge.

[Brianmoooore]

And welcombe to the zone on behalf of all the team members!

[telski789]

my MI16 had twin fans that stayed on for a minute after the engine was switched off,probably be a good thing if all cars did that!! mine sits at halfway,used to sit at 1/3 all the time till i got new rad,still,as my dad says,if it wasnt meant to get that hot the gauge wouldnt be that big!!

Tel

[Brianmoooore]

my MI16 had twin fans that stayed on for a minute after the engine was switched off,probably be a good thing if all cars did that!! mine sits at halfway,used to sit at 1/3 all the time till i got new rad,still,as my dad says,if it wasnt meant to get that hot the gauge wouldnt be that big!!

Tel

It's the lack of water punp that is mainly responsible for the heatsoak; the fans will just cool the radiator water, but I suppose this will encourage a bit of thermo syphon action.
Another way of looking at it is, if you restart the engine on a fanned car after a minute, then you will pump a load of cold water quickly into a very hot block and head!