99 Mack CH 613 intermittently overheating

[vvicess]

99 CH with E7  is intermittently overheating, the truck can go for two weeks with no issues or it will overheat every day. if it overheats it happens around 6 hours after running. the truck has a new water pump, thermostat, new radiator ,new head gasket.  can not find any coolant  lines kinked or blocked the fan hub is operating properly. had the heads pulled off and checked out   . i am not sure whats going on with this truck. any help would be appreciated.

[Challenger]

Is it actually overheating or is the shutdown light coming on?

Maybe a bad temp sensor telling the EECU its overheating when its not?

[Mackpro]

At the back of the water manifold on the LH side of engine. See if you have 2 temp sensors. One should face straight out the back towards the firewall and one out the side towards the frame/hood. If you do have two. The one out the back goes the the engine ECM and the one out the side goes to the guage. If your not getting fault codes and shutting down then the sending unit /wiring  for the guage might be bad. 

[Mackpro]

coolant temp sensors ETECH.pdf

[vvicess]

it is actually overheating , the shut down light dose not come on. it will some times as well push coolant out of the overflow line on the res tank when overheating . we have changed it to a one piece tank from a two piece tank but still having the issue. 

[Mackpro]

air compressor coolant lines.pdf

[Mackpro]

We see alot of early ETECH air compressors fail due to clogged coolant port on rear of engine  . If the head of the air compressor is rusty and looks like the paint is cooked off of it then the head gasket of the compressor could be blown causing coolant push. 

[vvicess]

sorry for the delay , the air compressor was really old so we changed it , the truck ran fine for a day the next day it  started the same issues again. 

[Bigdogtrucka]

Hi guys did you ever find out the cause too this problem?