7710 heater

[JAC FARMING]

well tonite when i had to pull a tractor up the hill i wanted to see if the heater would work. well nope. instead proably a half gallon of coolant came through the vents speakers and everywhere else. i have no idea whats wrong. it worked before it was parked. no air just coolant and it made a mess. hope you can help. thanks

 

[v240tic]

On my '83 4110 I had a similar problem. Turned out to be a defective o-ring in the heater valve.

 

[RodinNS]

Most likely the heater core is gonzo... Unbolt the cab roof and flip it up... then you will see the bolts on the heater core box. Take the top off that and have a look. With the engine running you should find the leak. If you want to be cheap you can mabey repair the leak with solder... otherwise, replace.
The flow valve is outside the heater box so I doubt that's the problem.... it could be, but I doubt it. They generally leak right down over the valve knob.

Rod

 

[sotxbill]

and/or the rubber heater hose is cracked and leaking...