Tomcat build of 1991 RRC: cooling system bleeder valve.

[linhofbiker]

Have a new radiator mounted at the back up high. I have been told that when I fill it, air will be trapped in the system, and that I need to have a bleeder valve on the engine near the water pump so that the air can be made to escape. Is there a cooling system bleeder valve anywhere, or do I have to install one. If so what is it and where/how should it be installed?

[mearstrae]

It's best to locate a vent plug at the highest point in the system. So if you have a radiator with a fill/vent plug, on top, you should be OK. My '95 R.R.C. had such a plug on top of the rad. Discoverys have a vent plug in the top radiator hose, but it's easier to vent those by pulling the filler/expansion tank loose and raising it above engine level. Same idea.

[linhofbiker]

It's best to locate a vent plug at the highest point in the system. So if you have a radiator with a fill/vent plug, on top, you should be OK.

That makes sense since air is lighter than coolant. So, when filling a completely empty system from the top, just leave the radiator cap off, and the air will naturally flow out. Is it still possible that air would be trapped in the lower parts? Is that why the suggestion of a bleed valve near the water pump was made?

Further research shows the need for a release valve at the highest point and that you have run the engine until hot, then open the valve to vent the air until it runs fluid only. This may need to be done several times and after have run the car 2-3 miles. I will get an inline bleeder valve for the highest hose near the radiator.