M50-Bleeding the cooling system

[John S Busby]

OK , I know this is a really wimpy question but what is the procedure for venting air when re-filling the cooling system.

I'm pouring coolant into the overflow bottle attached to the side of the radiator. It is fills up way past the maximum with bugger all coming out of the bleed valve (cap completely removed). What am I missing here? Any advice welcome.


JB

[glen-sj]

You did it ok. Which is to filled the coolant with the bleed screw remove, fill until coolant comes out of the bleed hole free of air bubbles. replace the screw and radiator cap. With the temperature and blower fan set on high. Start the engine and let it reach normal operating temperature. Slowly, loose the screw to vent air bubbles out until only coolant spill out. Check the coolant when engine has cool and add coolant to the correct level. Keep an eye on the level for the next couple of days. That is it.

[John S Busby]

Thanks for the response glen-sj, but are you saying I should keep filling the expansion bottle until only coolant comes out of the bleed valve? At the moment, neither coolant or air is coming out of the bleed valve even though I have topped it up above the max level, though without filling the bottle completely.

[glen-sj]

Thanks for the response glen-sj, but are you saying I should keep filling the expansion bottle until only coolant comes out of the bleed valve? At the moment, neither coolant or air is coming out of the bleed valve even though I have topped it up above the max level, though without filling the bottle completely.

Yes. You need to fill the bottle completely and watch the coolant come out of the bleed valve until no more air bubbles. Then screw the bleeder screw back on and the radiator cap. Start engine with cabin temperature set on max. with blower on high. Wait until the engine temperature reaches normal. Then slowly loosen the bleed screw to release air from the system, tighten the screw when coolant coming out is free of air bubble (about ten to fifteen minutes). Check the coolant level on the expansion tank when the engine has cool. Monitor this for the next few days and add coolant as require.

[John S Busby]

Yes. You need to fill the bottle completely and watch the coolant come out of the bleed valve until no more air bubbles. Then screw the bleeder screw back on and the radiator cap. Start engine with cabin temperature set on max. with blower on high. Wait until the engine temperature reaches normal. Then slowly loosen the bleed screw to release air from the system, tighten the screw when coolant coming out is free of air bubble (about ten to fifteen minutes). Check the coolant level on the expansion tank when the engine has cool. Monitor this for the next few days and add coolant as require.

Thanks glen-sj. Makes sense when you consider the level I was filling the bottle to (the max. when cold line) is some way below the level of the bleed valve. Getting lots of air and some coolant out now! Looks promising but can't try out the next phase yet cos the battery's gone flat since I've been working on the car!


Regards,


JB