Thermostat problem?

[States]

My temperature gauge in the dashboard is showing strange behaviour. The dial is moving into the red at random times...independent on whether I'm stuck in traffic or on the motorway. Temp seems to increase quickly and then decrease .....it's not as gradual as I would have imagined.

Also, my heating system does not seem to be working very well. We're going through a cold spell at the moment weather wise but depsite my daily journey of approx 20 miles I'm still cold on arrival at my destination.

Any suggestions?
Thanks

[Bill R.]

and thats why the heater isn't working.. being that low the car could be running hotter than you think also but the coolant is only occasionaly splashing against the temp sensors. I'd check that first anyway as soon as the car is cold and you can open the cap.

My temperature gauge in the dashboard is showing strange behaviour. The dial is moving into the red at random times...independent on whether I'm stuck in traffic or on the motorway. Temp seems to increase quickly and then decrease .....it's not as gradual as I would have imagined.

Also, my heating system does not seem to be working very well. We're going through a cold spell at the moment weather wise but depsite my daily journey of approx 20 miles I'm still cold on arrival at my destination.

Any suggestions?
Thanks

[632 Regal]

what car, what year, location?

might have air in the system.

our gages dont react fast, they have a built in delay so its common for them to all of a sudden shoot to the red.

fill out your profile or sig with your info.

[Erwin8r]

My temperature gauge in the dashboard is showing strange behaviour. The dial is moving into the red at random times...independent on whether I'm stuck in traffic or on the motorway. Temp seems to increase quickly and then decrease .....it's not as gradual as I would have imagined.

Also, my heating system does not seem to be working very well. We're going through a cold spell at the moment weather wise but depsite my daily journey of approx 20 miles I'm still cold on arrival at my destination.

Any suggestions?
Thanks

Most likely air in your system. I would bleed your system first, then look to see if there was a leak and have a go at the thermostat...

[Erwin8r]

Good bleeding instructions (from a friend from a different board):

What follows are instructions for filling and bleeding an M20 engine (similar process for M30 and M50)

Before you start have about 13 quarts of coolant, Phosphate free coolant compatible with aluminum mixed 50/50 with distilled water. NO WATER FROM THE WATER HOSE PLEASE. Tools. 8mm open end wrench (for the bleeder screw at the thermostat), appropriate sized washer (to loosen and tighten the bleeder screw on the expansion tank next to the radiator cap). Possibly a flat blade screw driver for loosening a hose clamp if necessary, an appropriate container for the old coolant.

It can be a long drawn out process. So let's start from the beginning. Have ramps near by and a way to drain your coolant. Now run the back of the car up the ramps, drain the coolant from the system, now coast the car off the ramps and put the ramps at the front of the car. Pull the car on the ramps and shut off the engine.

Turn your heater temp on full hot and fan speed on high. Open both bleeder screws. Now gently and slowly pour the mixed coolant into the radiator until it runs out of the bleeder screw on the radiator.
Tighten that bleeder screw very slowly and carefully taking care not to bind it as both the screw and the radiator are plastic, they could fuse together from friction if you do it to quickly and do not force it. Now the coolant may seem to have disappeared and well it has, it has flowed to the engine and this is good. Pour the mixed coolant slowly until it comes out of the bleeder screw at the thermostat. Tighten the bleeder screw at the thermostat. Now start the engine and allow to idle. You should feel the water hoses begin to get warm after a little while then you should be able to feel the heater valve begin to get warm, this is good if it does. Keep an eye on the temp gauge and you should begin to feel warm air out the air outlets. Now loosen the bleeder screw at the thermostat slowly and keep your hands and eyes away from it. A steady stream of coolant should stream out without air in the coolant. If all this worked, shut down the engine and allow to sit for about 5 minutes. Slowly remove the radiator cap just a short turn at first to relieve the pressure then when the pressure is off screw the cap all the way off. Check the water level again now on level ground. You will have to add more coolant. Keep doing this until the level is at the correct level.

You are all done now, clean up the mess, wash down the drive so the animals won’t lick the coolant, and dispose of the coolant properly. Now wash the car, check the coolant level one more time, start it up and allow to idle for a few minutes, checking the temp gauge. Return the fan speed and heater control to the normal positions and observe the coolant temp. If all is ok you are done and can go enjoy your clean and properly cooling BMW.

I have used this technique 7 times now successfully and it makes the air in the system for the M20 almost a moot subject. I have also used the other methods with no success, even a month ago I followed different directions before actually trying mine because I doubted myself but never again with the M20 air bleed process. This whole process takes about 20 minutes and your lips wont touch and coolant, nor will you need to remove any hose.

Hope this helps you.

Michael
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