Running temp on 325i problems & Bleeding

[MarkB]

Just changed the thermostat in my 325i touring as the car was running cold i have tried to bleed the system but the car won't run tidy. The gauge is showing just under halfway what is the problem as she won't go over halfway even if I leave the car tickover for thirty minutes. What is the correct way to bleed the system?

[Davenotouring]

Where your temperature guage is sitting is ideal!

If it doesn't go above half, then it is fine!

To bleed the system, run the car from cold with the heater turned to max (red) and undo the bleed nipple on the thermostat housing. (Don't undo it completely, just loosen it so the gap in the side is open - Have a look and it'll be clear what I mean!) Once it is a constant flow of coolant, close it again.

Once the car is up to normal operating temperature, open the screw again, and make sure there is no air in the pipes. Leave the expansion tank cap off during this aswell to let air out.

[Simon]

Hi mate

To bleed the system get the car up to running temp with the cabin air temp guage on full (in the red), switch off, undo the bleed screw on top of the thermo housing until all the air is released, then leave to cool and top up the system.

Car running at just under halfway sounds perfect to me!

[Simon]

What he said!

[Davenotouring]

Both said pretty much the same

That's shown that the temperature is sitting in the right place anyway!

[MarkB]

Thanks for the help my other BMW's temp gauge are dead centre not just below I think the car is running on choke or cold all the time as it's only doing between 10-15 mpg around town the car doesn't do short trips.

[Davenotouring]

Hmmmm.

Is it between the first and second lines after the blue on normal running temperature?

Round town, I'm was lucky to get better than 15mpg round town.

On a run, you should get at least 25mpg.

If not the car isn't running correctly, or you have a heavy right foot, like me.

[Simon]

Thanks for the help my other BMW's temp gauge are dead centre not just below I think the car is running on choke or cold all the time as it's only doing between 10-15 mpg around town the car doesn't do short trips.

Try changing the blue temp guage, this is the sensor for the ECU (brown one is for the temp guage) and can cause the car to over-fuel.

[Brianmoooore]

When you warm up the engine after messing with the cooling system on a 6 pot E30, you should not only have the heater set to full on, but you should have the heater fan on 1 or 2, and check that the air begins to warm up as the engine does.
6 pots can suffer from airlocks that stop the heater water circulating and cause rapid overheating of the cylinder head. Cure is to loosen a heater hose at the bulkhead and release the air.

[Davenotouring]

While you're here Brian (legend)....

Which is the inlet hose.....top or bottom?

[Brianmoooore]

The top one that comes from the back of the head IIRC.

[Davenotouring]

Thanks.




When I replace my engine, I wanna flush out all the gunk which will be in the heater matrix, can I run a hose through till it runs clear?