Head Gasket?

Open the hood and take the radiator cap off. Max out the RPM and let off with the Jake on. If it blows coolant in the air head gasket is bad.

 

wow i wish i knew that an hour ago lol

 

Don't remember exactly what did it, but it really struck me the other day that I'm one of those old timers to most. 37 years this fall, sure have been a lot of changes in those years. The truck I learned on was built 50 years ago.

 

D600 with a 5 speed on the column? No you probably had a real truck like a 237 Mack with a 5 speed or a White with a 230 Cummins and a 7 speed?
Seems I remember air cooled compressors were normally on gas burners?

 

71 2 axle Binder, 220 Cummins and a 10 that you only had to throw the lever close to the next hole to get it to go in. If it was moist, you'd get a quart or better out of the air tanks everyday.

[Edited out old man's fading memory banks]

 

I'll have to look but I'm positive the compressor on my 3406A is coolant cooled.

 

I had to go look, memory is going. I changed one on either the 220 or a 335, I could have sworn there were no coolant lines, but I've found pics showing otherwise.

 

I'm pretty sure my 3406A has a TuFlo 550 on it. I tore the engine down 18 months ago so I don't exactly remember either but I swore there were coolant pipes to it.

 

Being a 99, it may have an air over electric heater core control valve on the Cab or Bunk. Look for a tiny airline going to either of them. When bad, once desired temp is achieved, they allow air into the coolant. Won’t do it as long as it’s open and coolant is flowing through heater core(s). Causes intermittent symptoms that mimic a cracked head or bad head gasket. Simply shutting off the valves under the hood will stop the problem, till they can be changed. Makes for a real head scratcher.

 

Thanks: Did not know that truck had air to sleeper water valve. Good point.