Air bound coolant system?

[Madmack83]

I have a 2000 ch613 with a 1996 remaned engine that was swapped in. It had to be retrofitted with a tubular style oil cooler because the pancake style one was slightly different in shape at the mounting area to block. Some of the plumbing had to be changed as well. The tractor  appeared to be overpreasurizing and was blowing out of the over fill. I took everything apart nothing clogged ,changed water pump no cavitation on housing,changed thermostat, air compressor,did combustion test as well negative . Still does it but not all the time loaded or empty. Temp gauge will go up high cold air will start blowing out defroster shut truck off about 60 seconds, start it back up temp goes immediately down and blows hot air again. I drained the fluid out last night and got 4.5 gallons of antifreeze out I took a coolant hose off air compressor blew a little air through it gurgled and then then another 3 gallons came out. I filled it back up it would only take 4.5 gallons  I disconnected the small hose that goes to the fill tank blew some air into it  it gurgled again and took 3 gallons of antifreeze.whats going on I feel like its getting airbound especially since it does not do it constantly. I had it over at the dealership they did exactly what I did only thing different they did was change from a 2 piece tank to a steel single tank . Still does same thing they tried bypassing the air compressor also and did a combination gas test so it's not a head gasket.

Edited December 29, 2018 by Madmack83
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[Mackpro]

Is your radiator cap on the radiator or do you have the expansion /surge tank on the firewall? If you have the expansion/surge take set up,  I’d check/replace the small line from top radiator hose to the expansion/surge tank. We have seen these collapse inside and cause all kinds of weird problems.

[Madmack83]

Yes I have the separate tank for expansion near the firewall I did replace that small line in the beginning of all the problems that was the first thing Mack recommended now the other question is is there supposed to be a check valve in one of those fittings that goes in either to the fill tank or to the top of the pipe that goes into the radiator for the small line?

[Mackpro]

Some have a check ball in the elbow fitting at the sure tank . Usually the 2004 and up ASET engines have them . The problems occur when the check ball sticks 

[85snowdog]

I've heard stories of a rag left in a lower rad hose will give the exact same problems you described .

[LilMartian]

Also, if, just on the off chance, you pulled the “y” hose from bottom of the pancake oil cooler, they use a screen inside of it and when you removed and didn’t find that screen, it may have gotten in the lower pipe and could cause same effect as the rag issue. Something else to think about. Small possibility that and if you put it back, the rear water line to air compressor from the back corner of the block could have some blockage due to casing materials. Mackpro can attest to that I sure. There is an old bulletin on it and correction is to move the back water line from corner of block around to the water manifold.  Also, had one that did similar and ended up finding that the water line from the water pump to compressor had pin holes, sucking air in and had collapsed near the fitting at the water pump. Maybe something else to think on