My pump was running all the time and died. I picked up a used from a guy for 20 bucks. I can hook it up and kink the hose and it goes off immediately. It used to run just until the WTS light went out. I swicthed out the vacuum tank, but no fix. I couldn't seem to find where the leak was. Any clues? theres a little manifold under the dash on passender side that i am suspct of and two lines that run off of the vacuum tank. One closed off by some switch and the other is not. Not sure which direction to run the problem down. I have manual warn hubs so its not the automatic part. Let me know what's the best avenue of pursuit???

 

If you have the shift on the fly 4x4, it is most likely the lines from the frame down to your hubs on the axle that need replaced.

 

I had two leaks - one when the 4X4 was off (bad ESOF module) and one when the 4X4 was on (cracked vac lines at the wheels - both sides). I replaced the ESOF module, then I cut about an inch and a half off the ends of the vac lines to the wheels and reinstalled. Life is good here.

 

My rig had 31,114 miles on it in 2010 when I found it....it was absolutely mint....the winter came....driving to work after a nice snowfall, it was a blast stunt driving all the way to work, when I got there...a co-worker had plowed a 4' pile of snow at the entrance...hah ! I've got a super duty dually 4x4....ill just turn this little **** from the comfort of the cab, and bash right through. But....after a few minutes of carefully removing the now....6' high mound of snow....I discovered those vaccum lines to the hubs were as brittle as hummel porcelain. That's where I'd look first. Happy holidays all

 

On my truck the electric valve that sends vacuum down to the front hubs was bad. I pulled the valve and plugged the lines to keep the vacuum pump from running all the time. Probably won't remember to replace it until we get a winter when it actually snows.

 

Yes happy Easter mtdigger,
The electric switch on passenger fender wall, is it the 4x4 switch for hubs? I guess the TC will shift without that being hooked up?

 

Yep - the ESOF on the passenger fender feeds vacuum to the hubs and that is separate from the TC.

 

I'll check that out bright and early. Seems like there was a red vacuum line and a black one that went to it, but ill run it all down tomorrow.

 

This should help.

PVHS - Pulse Vacuum Hub Solenoid

 

I was looking all too far from the pump. the Hvac line was cracked about 1/2" from the vacuum tank. I had another one i had gotten when i bought a used pump from a local guy. I did go ahead and switch the tee out to an elbow on the side where the hubs lock in. I have manual hubs so it ain't no big deal. I'll probably pull the switch and wiring off where i can use the vacuum locks on the 04 SD FX4 chasis i bought to go under my 69 crew cab. You can check that thread out if you care to. I havn't done a whole lot to it lately. I'm rebuilding the tranny and getting the motor prepped before i start the swap.

 

I did replace the pvhs as well...after having the climate control system stop working as well, I forgot to mention that