Filling Coolant

[BugEyeBear]

What is the proper way to fill the M35A2 cooling system?

I DO NOT have a heater attached to my cooling system.

I had a very small coolant leak at both of the intake manifold hoses (a very slow "drip, drip, drip" once the cooling system built up pressure) caused by loose hose clamps. I tightened ALL of the hose clamps on the engine, topped off the radiator (it was about 3/4 of a gallon low due to the intake manifold hose leak), and ran the engine for about 20 minutes at about 1200RPM. Temp got to about 150F or 160F on the guage. I then shut it down and let it sit overnight. Checked coolant level the next day & it was still full.

Do I need to "Burp" the system to get any air out? OR should it now be full with no trapped air? (It appears that the upper radiator hose, upper radiator tank, & filler neck are all higher than the intake manifold, & I'm assuming that the thermostat opened enough at 150F to allow water in and/or air out.)

Does the thermostat normally have a small "burp" hole in it (to allow a small flow of water to pass thru the thermostat, even when cold/closed)?
Other than the initial 3/4 gallon top-off, no additional coolant needed to be added as the engine warmed up.

What TM details filling the cooling system?

Unless I can find a TM that tells me to "Burp" it I'm gonna do a road test, get the engine up to 190F, let it cool down a bit, and then check the coolant level again.

Seems pretty straight forward.... But I thought I'd ask, just to be safe.

 

[Jake0147]

Air forms a pocket in the top of the radiator, and in the intake. To check, remove a plug or sensor on the intake right behind the thermostat. With a full radiator, you should get coolant.

The thermostat is kind of not what you're picturing, it's full flow in the open or closed position. It's more of a "diverter valve" than an "on/off" valve. The "closed" loop just sends coolant out the path right back to the water pump, so it circulates within the block to prevent heat from concentrating in specific areas. In the "open" loop, it diverts a percentage of the flow to the radiator based on it's percentage of opening, until it fully opens (which it probably never should...) when it is capable of completely blocking the "recirculating" loop and sends all of the coolant through the radiator.

Your best bet is to remove air from the radiator by filling as you did, remove (most of) the air from the intake by venting it with the radiator full so that fluid will find it's way in there, and drive it. It won't warm up and have enough flow to "burp" if it's just idling.

Remember too, "full" is just to where you can see it in the bottom of filler neck. If you fill the radiator to the top, it will ungraciously expel the portion that it does not want during the test drive.