when i turnthe heat on i get a hissing from inside the cabin i assume behind the dash with a noticed loss of power
if i hit the go pedal it stops till the truck stops pulling then the hissing begins again when i get off the pedal it goes away again the hissing only happens when the heater control on the dash is engaged
so going on this and what i know of cars/trucks and vacuum actuated devices there is a leak
but im thinking that diesels dont create vacuum or do they ?? as a oldsmobile i used to have used the power steering pump to create the power assist for the brakes to work

well any way is this a know issue ?

love these cold weather maladys

mike

 

That is the EBPV activating. Tap on the brake will also make it stop. It helps the engine warm up faster.

 

the problem is that it never stops

 

Sounds like it is stuck

1. EBPV valve is stuck
1.5 EBPV solenoid is bad or unpluged

 

You could also have a bad engine oil temp sensor or a bad thermostat causing those issues. The EBPV is supposed to be disabled one the engine oil temperature reaches 167 degrees.

 

As Alan said it sounds like the ebpv is stuck or the actuator rod has came loose. Mine use to do that even when it was warm outside. I gutted mine so no problems now. Reach under there and make sure the clip is holding the rod on the actuator.