I have six months ago fitted new hub seal, auto locking hubs and a PVH solenoid all from (Autonation Ford) , now here's the problem I'd like to solve.

Every time i start the truck whether it's been overnight or just gone to the store for ten minutes the vacuum pump starts up, so some where i have a vacuum leak!

I have checked for vacuum leaks with my Mityvac from the hubs to the pump all okay ,but as soon as i check from the vacuum pump to PVH solenoid i lose vacuum.
So i have disconnected the PVH solenoid and plugged the rubber elbow coupling and cycled the key to activate the vacuum pump and it holds 15''hg pressure, so is it my new PVH that is leaking or do i need to look further?

I have checked for leaks inside the cab at the heater box and all okay, so is there a way to check the PHV solenoid out?

 

I only just saw this mate and you may have already fixed it, often it is the vacuum lines to the hubs itself that leak. Sounds like that isn't the case. Can you be sure that the PVH is cycling correctly? Is it getting the electrical signals to cycle?

Frankly I hated the old vacuum actuated ESOF, and replaced the with Warn manual hubs on my previous trucks

 

No haven't fixed them yet , still work in progress, yes the PVH is getting 12vdc on the middle pin and 0 vdc on the outer pins , the PVH solenoid is brand new from Autonation Ford (US) , the blend door is work as is should and the vacuum pump turns on/off after about 30 sec , in saying that the vacuum pump starts up each time i start the truck even after say 15-20 minutes.

If i disconnect the PVH and plug the vacuum lines it will hold 20'' hg over night or for a couple of days, which leads me to believe the new PVH solenoid has cacked itself.

Is there and way to test the vacuum side of the PVH solenoid , it will hold vacuum on the inlet side (red line) but as soon as i connect both line it looses vacuum.
Any help will be appreciated .

Glad to read you finally have your truck fixed / sorted out and is read to do a trip around the block.

 

It does sound like the PVH solenoid.
If you back-probe and ground either of the outer wires with the ignition on, you should hear the solenoid click for both sides. If it doesn't click on one of the sides, the PVH is bad.
I have attached what words I have on the PVH. Not sure what help it will be.

When you activate "4x4" do your vents go to Defrost?

 

Thanks Adrian for the info I'll give that a good read through shortly, i have both batteries out at the moment about to fit 05-07 projector headlights.

Can i test the PVH with a 12v battery on the bench?

 

Blue, still waiting to hear about the projectors - so glad to hear your projector project is progressing

 

Hey Simon, new project is coming along good, the lights are an easy fit , they also are adjustable on the top fittings.

The PVH solenoid is another story.

 

You should be able to.

 

Now that I've got the battery and battery cradle out I'll pull the PVH and try testing it on the bench like you suggested Adrian.

When they put these trucks together there wasn't a great deal of thought put into it about where certain components would be fitted, the PVH solenoid is bolted right under the vacuum reservoir so you have to remove the battery and everything else with it to get to the PVH , but anyway it's ll done now.

 

Often problems in the PVH occur from crap being sucked up from the hubs, but if you replaced the seals etc. before putting this one in, maybe you just got a bad one.

 

Update- i have bench tested the PVH solenoid , grounded the middle pin and 12vdc on either of the outer pins and you can hear the solenoid working .

Then i have applied 15''hg vacuum to the esof system and it's holding pressure , i also heard the blend door closing at 10''hg , what's next ? another new PVH.

 

Blue, buggered if I know mate. If I understand correctly, you are holding Vacuum fine with the HVAC and the hubs, and the PVH is operating correctly, and sounds like it is getting the correct signals.

The only thing I can think of is if the PVH has some internal seals that have failed, but if so, its a problem I am not familiar with. I'd inquire with the users in the Super Duty or 7.3l forum, as I'd expect them to be more knowledgeable than I and the system is essentially the same for LHD trucks (although I think some of the pipe routing for the HVAC is different).

 

Thanks for your assistance so far Adrian, the vacuum system is working as it's suppose to the only thing i think is suspect is the new PVH , i'll try the old PVH on the test bench and see what i come up with.
Is thew PVH solenoid supposed to hold vacuum on the either side?

 

Okay here's an up-date on the suspect PVH solenoid.
The PVH solenoid i fitted six months ago i pulled which i suspected was leaking down, bench tested again and found not to be holding any vacuum at all , that was purchased from Auto Nation Ford.
I bit the bullet and purchased another PVH Solenoid from the same outlet (ANF) along with some other parts , i tested the new PVH on the bench with the mityi-vac it held 15''Hg vacuum for about ten minutes so it was better than the last one so i set out to fit it and after a while climbing over the engine bay it was all together.
Connected the batteries and fired the truck up, the vacuum pump ran for a couple of minutes than stopped as it should, so all is well BUT wait, i went back and started the truck 1 hour later and the vacuum pump started.
Question: does this happen with your truck?

I have emailed Auto Nation Ford with no reply as yet.

 

Hey mate - which Autonation Ford did you order from?