how to air bleed coolant 1995 E150 5.8L with front & rear heater

[Bertsky]

New radiator/thermostat meant coolant drain/fill. To refill & bleed, service manual says to disconnect heater-to-water-pump hose at water pump and fill at radiator cap until coolant starts coming out of that hose, reconnect and finish fill. Start engine, bring up to temp until thermostat opens, shut down and wait for cool, open radiator cap and fill as needed. Repeat heat-up, cool-down, fill cycle until it's full. This makes no sense to me BECAUSE:

Coolant exits the engine to a hose that goes to a T-connection. The T-conn. exit pipes go to both front and rear heater feed lines. Both heater return lines flow into another T-conn. that merges flow to a hose that goes to the water pump feed. The water pump pumps back into the engine via the bypass hose, OR, once the thermostat opens, pumps into the radiator before feeding coolant back into the engine after radiator cooling. Here's what I don't understand...both of those T-connections are the highest points in the cooling system; higher than both heaters, the engine and the radiator (they are located just under the cowl at the top of the engine compartment). So HOW will the air bubble EVER be pushed down into either the engine and eventually to the radiator so it can be expelled? AND how will the coolant ever rise higher than the radiator cap I'm filling from, to reach the T-connections at a higher point? Can anyone make sense of this?

Here's my problem. I know I have an air bubble I can't get out (I didn't disconnect that hose when filling). The heater heat temp. goes up and down as the air bubble goes into and out of the heater core (intermittent) and the coolant gauge is suffering from air bubble effects intermittently as well, because it will shoot up to near HOT and then glide back to it's normal temp position at center-gauge. It runs fine until thermostat opens then intermittent behavior begins. Has nothing to do with cooling air-flow through the radiator and the radiator fan is operating fine. I can see no leaks and am not losing coolant. I have run the gauge sender connector to ground with key on and it will jump all the way to HOT so I know the gauge is working fine. I don't want hot/cold spots running around my engine block. No such thing as a bleeder screw in these engines. I'm tempted to interject my own air bleeder valve near the T-connectors. Can anyone else enlighten me on any of this? Thanks!


PROBLEM SOLVED: I knew there was still a chance the problem was with restricted flow and not an air bubble (or both). So, I drained and flushed each coolant component separately (heater core, rear heater core, engine block and radiator). The rear heater core was plugged. The front heater core was full of brownish black crud. The engine block was mighty clean. The radiator was new, so clean except for what came from elsewhere. Rear heater core replace is a pretty big job I didn't have time for so I removed the hose attachments going to the rear heater core and plugged the metal T-Lines going to those rear heater core in and out hoses. After much flushing in both directions, back and forth, the front heater core finally flowed clear. Reassembled, refilled and the temperature is now ideal. So the problem was restricted flow.



BTW, if you are going to plug the rear heater lines like I did make sure you plug those lines with rubber caps (5/8" caps in this case, available at your local auto parts store). Do not use a piece of hose and loop the in line back to the out line. simulating flow to and from the rear heater core. Why? Because if you do that and the front heater core is not flowing well, the coolant will follow the path of least resistance thru your loop and back to the engine. In this case coolant will flow fine, but your heater will be cold. If you then use the lines feeding the T-connections to flush the front heater core, the flush will do the same thing and you'll be scratching your head wondering why the flow is good but there's no heat!

[aleekat]

Have you tried parking on a hill or ramps, front end high?

[Bertsky]

I have tried that via steep streets, BUT looking at heights of components, the van would need to be nearly vertical before the radiator cap is higher than the T-connections. Sure do hear the air gurgling around the system though.

[Bertsky]

PROBLEM SOLVED: See original post which I edited.