Just wondering if anyone knows what this hose is? it's a white plastic vacuum hose on the passenger side of the engine bay close to the firewall. mine is all rotted and broken in half. not sure what it goes to. i've owned a few turbo vehicles, and those plastic hoses are used in the turbo setup. but this one doesn't seem to run anywhere near the turbo. any ideas?

 

I'm not familiar with the diesel setup, but all trucks of this vintage era utilize the white vacuum hose for the blower door modulator atop the cowl, just under the hood on the passenger side. Gas trucks fer sure. Do you have air blowing out the vents of the dash or defrost only?

Once again, if it's close to the gas trucks, it should be the same for the diesel. I could be totally wrong too.

 

Correct. You need it hooked up to the vacuum canister so that your heater works properly.

 

On my 460 that hose had a rotted out section and my heater would only blow out the defrost. I bought some black rubber hose that had a little bigger diameter, cut out the bad section of the white and then just pushed the white into the black. It was pretty tight but seems to be working pretty well. Heater and AC will now blow out the vents even under a heavy load.

 

Can you upload a picture? I have a 7.3, moving this to the 94.5-97 7.3 forum would help you, lots more of us there!