Bleeding the air out of the cooling system idea | Ford Explorer Forums - Serious Explorations

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Bleeding the air out of the cooling system idea


December 25, 2017
Reaction score
City, State
Nampa, Idaho
Year, Model & Trim Level
1997 Explorer 5.0 AWD
Ok, I spent the last 3 months rebuilding my 4.0 and tackled removing air in the cooling system.

Install a ball valve in the intake above the thermostat.

I drilled a 7/16" hole with my drill press, to keep it square and tapped for 1/4" pipe.

Home Depot brass fittings below, all 1/4 inch pipe thread.
1, 90 degree, male on one end, female on the other.
1, male coupler
1, small ball valve
1, 90 degree 1/4 inch hose nipple
3 feet of clear 1/4 inch hose
1, plug

You can not do this on the motor unless you have a way to fully remove all the aluminum, there will be a lot.
Make sure you do not run the tap too far into the hole, you want some taper in the hole so the fitting will seal. Test fit your fitting as you go.

Fill the radiator all the way.
Put the cap on.
Start it and open the valve, let it push out some of the air through the hose into the overflow bottle.
Shut it off.
Add more coolant to the radiator.

When you are satisfied that you have removed all the air, remove the 90 degree hose nipple and put the plug in the valve.

I did this about 3 times but I let it come up to temp each time.
The clear hose will build pressure so make sure you have a good hold of it when you open the valve and aim it into the overflow bottle.
I blew coolant all over everything, yea, I did that......

So far I have 20 miles on this motor, trying to fix some gremlins at the moment but I have no air in the system.
I will post some pics later of the finished assembly.

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I like how you solved the air in the coolant system issue, but would it be easier with something like this brake bleeder valve and a piece of clear tube? You could just run the tube into any container and bleed away until there is no air in the system. Then leave it in place for next time.

BKennedy, that looks like a good idea too. You can pump the coolant wherever you want to.
As long as you come up with a way to close off the opening in the top of the intake manifold once bled.
The only reason I am going to put a plug after the ball valve is so if it gets unintentionally opened it can not pump out the coolant.

I was not smart enough to take pictures as I did it but hopefully you can get the idea what I did.
There has to be other ways to accomplish this so use your own if a better idea arises.


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When I was in high school, we had an auto shop project, a 55 Chevy we took to bracket drag race on weekends. We did something a lot like this to dump hot water (we didn't use coolant for 1/4 mile runs). We dumped it to get the engine cool as quickly as possible for the next run. It looks like something I would do, my only comment is to watch for the ball valve temperature ratings. Not all ball valves are rated for hot water. Nice job!

Thanks for the comment Roadrunner. The temp was a concern for me also.
With all the bad replacement parts and other products these days, you have to be suspect.
We will see if it holds up, if I have issues I will comment.

This is the one I used.

Product description:
This lead free ball valve is forged from bass and includes a lever handle with female connections on both ends. Perfect for residential and commercial use on water, air, steam, oil and gas applications. Designed for minimum pressure drops. Each valve is corrosion resistant.