View Full Version : air in water/coolent line

08-10-2007, 08:13 AM
i am installing a heater valve in the water/coolent line in my 1500 mg midget. by adding this in air is going to be in the lines then. is there a way to get the air out before i start the engine so that all the air won't be running through it or will it work itself out someway quickly?

08-10-2007, 08:29 AM
Run the car with the radiator cap off from cold. Let it idle until it hits the temperature the thermostat opens up.

As soon as the water pump is able to cycle water through the car, the air will find its way out of the fill hole.

Sometimes you need to be standing there to add more coolant to keep it full, as air finds its way out.

The way my Sprite radiator works with no overflow reservoir, there is always air in the system when it has cooled down. If you fill it full, it will blow some water through the overflow tube since the mixture expands when heated. That's normal in my case.

08-10-2007, 11:26 AM
And would you beleive all cars use to work that way.

08-10-2007, 02:37 PM
Well they all had such big radiators that a little air wasn't as big of a deal /bcforum/images/%%GRAEMLIN_URL%%/wink.gif Oh, and we didn't mind dumping chemicals out onto the roadway. It kept the roads looking shiny and new!

PCV on my 54 Ford is a pipe that runs from the crankcase to the ground, haha.

08-10-2007, 04:38 PM
Just to confirm, the regular 'cap' on the 1500 is on the overflow tank, but there is a brass threaded cap in the centre of the engine block. You should be able to fill the rad without too many bubbles through the brass cap.

I believe that the manual calls for the overflow tank to be half full during initial fill. (Can someone verify?) Then, as noted above, close it up, run it until hot. Run the heater to ensure that the whole system is flowing, and top up as needed.

08-10-2007, 08:59 PM
so which one of the caps do you have off when the engine is running to get the air out of the system (the cap on the radiator or the one on the overflow tank)?

08-11-2007, 07:08 AM