Draining and filling the cooling circuit correctly

[Feret]

Hello, I remind you that I am in France, so I hope that the Google translator will not distort my request for information too much...

I will change my coolant on my Rover 75 CDT. I already did it 5 years ago, but I had problems: The official procedure I have, asks to disconnect the lower radiator hose, then unscrew the drain bolts on the engine block...

With this method, I have never been able to remove the entire volume theoretically contained in this engine! Does the thermostat prevent total draining?
Should I go driving to warm up the engine and open the thermostat, then as soon as I come back, drain the boiling liquid ?

In addition, when filling the cooling circuit, the liquid never comes out through the bleed screw of the Webasto because it is located higher! The only solution found is to detach the expansion tank, and hold it higher than the purge by filling... ( (It seems to me that this is the method for lze V6 engine).

What do you think of this method ?

And finally, it is advisable to operate the engine leaving the expansion tank open, and to wait for the cooling fan to start... But this engine heats up very little, and I managed only once, and by 35 ° to start the fan with the car in the garage, at accelerated engine idle.

Is this normal please?

Thank you in advance for your competence

[SD1too]

Frank; I don't have a diesel but I will try to help based on experience with my V6.

Originally Posted by Feret

The official procedure I have, asks to disconnect the lower radiator hose, then unscrew the drain bolts on the engine block...

MG Rover procedure:

1. Cylinder block drain plug
2. Radiator bottom hose

Originally Posted by Feret

I have never been able to remove the entire volume theoretically contained in this engine!

Don't worry. This applies to everyone!

Originally Posted by Feret

Should I go driving to warm up the engine and open the thermostat, then as soon as I come back, drain the boiling liquid ?

No, you risk scalding yourself.

Originally Posted by Feret

... when filling the cooling circuit, the liquid never comes out through the bleed screw of the Webasto because it is located higher! The only solution found is to detach the expansion tank, and hold it higher than the purge by filling... (It seems to me that this is the method for the V6 engine).
What do you think of this method ?

Try it!

Originally Posted by Feret

And finally, it is advisable to operate the engine leaving the expansion tank open, and to wait for the cooling fan to start.

That is not quite correct. Run the engine with the expansion tank cap off until the level begins to rise up the neck. Now fit the cap. Continue running the engine until, MG Rover says, the fan starts. This is unlikely to happen, not even with the petrol engines! I wait until the temperature gauge shows "normal" which has always been satisfactory.

Simon

[Feret]

Thanks a lot...

indeed this confirms what I thought, and what I did 4 years ago and 50300 km!
I also know that after driving, you have to check the level in the expansion tank, and if necessary remove coolant to return to the "max" level.

have a good weekend !

[Mike Noc]

If you are having problems bleeding the diesel engine then remove the small pipe going into the top of the expansion tank, check that it is clear and also that the path into the expansion tank is also clear.


The diesels are usually a doddle to bleed - just pour the coolant in and once the expansion tank is showing a level run the engine at idle until coolant comes out of the bleed screw hole, replace the bleed screw and then top up again once the engine has cooled down after a run.