2000 Mack rd688 e7 air compressor help

[Moparmike]

Good evening 

today my driver was hauling asphalt (dump truck) 

and suddenly temp went up truck shut off

he gets out check under the hood 

Fires it back up and the air compressor is pushing water out the side and through the over flow (reservoir) tank 

I’m hoping that it’s just the compressor and nothing internal 

any help or guidance will truly be appreciated 

21 yrs in trucking and I’ve never had this kinda issue 

but anyway 

to get the load off 

we open the valve for the water to flow through the heater core and left the cap loose so the pressure wouldn’t build 

got the load off and truck home 

temp was about  180

drain tanks water and dripping out the air compressor 

none in oil 

 

so am I correct on air compressor 

and if so does this have to be timed like injection pumps 

Again Thank you 🙏🏽