I posted this in the Super Duty section, but haven't received a lot of replies.

https://www.ford-trucks.com/forums/1...-question.html

Moderators Tom and Senix have been most helpful with info posted, but I need some more assistance please.

Several months ago while working on my 4WD issues, I discovered that my axle seal was leaking when my driver side hub assembly would not hold vacuum. At the time I also popped the cap to my PVH solenoid and I believe I accidentally switched the plastic disc and covered the wrong valve inside. I'm thinking now that I had two issues going on at the same time and I fixed one, which was the axle seal.

Currently, when I switch to 4WD High the truck will periodically fully go into 4WD as I can tell by my tires and axles bind in a turn on dry pavement. When I switch back to 2WD and drive for a short time I feel the truck out of 4WD(transfer case disengage) but the axles will not disengage. To disengage the axles on both sides I have to switch my hubs manually from AUTO to LOCK several times, which resets them, then reach under the truck and twist my axles until I feel them release. Therefore, there is not enough vacuum to release the hubs via the ESOF system.

If I have the plastic disc on the wrong valve that might explain why they won't disengage the axles. When I switch the disc to the other valve I then have air blowing out of my defrost vents.

I found this pic on the internet and his covered valve appears to be towards the front of the truck. Mine is on the other valve, towards the cab(rear).



Can someone do me a favor and pop the top off of your PVH solenoid? Underneath there is a foam filter and under that are two brass valves. One of the valves is covered with a plastic disc.

I need to know which valve is covered with this plastic disc. I had to replace my foam which had deteriorated and I don't remember which valve is covered.

If the correct valve to be covered is the one towards the front of the truck, and when I put the disc on that one, which makes the system default to blow out the defrost vent, I'm thinking my PVH solenoid is bad or working incorrectly. To test it I first have to know that I have the plastic disc over the correct valve.

Any help would be greatly appreciated.

 

The Disk is installed closest to the Fire Wall. Almost all issues with ESOF is due to lack of maintenance of the Hubs. See Guzzles ESOF Lube directions.

 

Then you are saying the picture above shows the disc is covering the wrong valve? The pic above shows the valve towards the front of the truck is covered.

I took both of my hubs apart and regreased everything according to Guzzles' write-up. My hubs do lock into 4WD, but my issues is that my axles will not disengage as they should once I switch back to 2WD. I'm thinking that there is not enough vacuum to make the hubs disengage.

 

When installed on the R/H fender the disk should cover the hole closest to the firewall. The Hubs engage by applying vacuum for 4 sec to engage and six seconds to disengage (or visa-versa). You can use a vacuum gage to check to see if the solenoid is activating for the prescribed period.

If you've done the maintenance to the Hubs, you may also have a seal issue on the Hub Seal where it meets the Axle (Yellow Seal).

If you have a compressor which you can supply < 5 PSIG you can tap it in AFTER the solenoid spray the lines with soapy water to find a leak.

Also, ensure you have both (+) and a god (-) on the Solenoid connection.

I have never replaced one as the problem for the Hubs disengaging. Most times I find a deteriorated rubber vacuum liner at a splice or "T" connection, bad seal, or improper assembled Hub. It only requires 1.5" Hg to activate / deactivate the Hub. If your Vacuum Pump Stops after say 30 or 40 seconds, you have more than enough Hg.

Tom

 

I had a similar issue when I used a set of Dorman hub o-rings. Found some USA -152 o-rings....solved.

 

I don't think my hubs are leaking. I took the hose from the fitting at the frame which goes to each hub and pumped the vacuum up to 15 and both held. At first my driver side did not hold and that is when I tore it down and replaced the axle seal and o ring.

Could my solenoid allow enough vacuum to engage the axles but not supply enough vacuum to disengage the axles? Again, this is on both sides, not just one. Once I switch back to 2WD I have to go to each hub and turn from AUTO to LOCK several times, and then reach under and twist the axles back and forth to disengage them.

 

Well, I called the Ford dealership and had him pull a new solenoid off the shelf and open the top cap. He advised once opened and the connector facing him the valve on the left(like picture above) should be the one that is covered. On mine, the valve on the right is covered, which is incorrect.

Yesterday, when I switched the disc to the valve on the left, which is the correct placement, my vents default to the defrost vents, which means I have a leak somewhere. Hopefully it's just my solenoid is bad. I remember trying to troubleshoot the system with a handheld vac, but I could not find a leak in any of the hoses.

Back to square one.

 

Anyone have a spare solenoid that you are not using when you switched to manual hubs, and willing to sell?

Or....where is the best price for this solenoid online?

I'm not sure how to test this as being the problem, but what I have done so far points to this solenoid as being the culprit. I'd hate to pay dealer cost and then find out it is something else.

 

$38 at Rock Auto

 

Thanks. It's not OE but made by Dorman. I guess there are no issues with it not being OE?

I'll try to verify this is my problem since I borrowed my last hand vacuum pump. I guess I need to make a trip to Harbor Freight as well.

 

If you're looking for the OE Part you won't find the original unless its excess stock. Ford had many revisions and eliminated it all together during the 6.0 Lifespan. The original casting was #F81A-9H465-BA 921DO341.

HOWEVER, FMC (OEM) remanufactured the same valve for the 2010 and later Ford Models (#7C3Z-9H465 A which is the exact same valve).

Some parts persons have to be aware enough to check the cross-reference or Sheet #9H465-BA Blow-Out Diagram for the 99.5 and later. Otherwise it will show as Obsolete and they'll suggest the Dorman as replacement.

 

............

 

Here is how I tested my solenoid. I tested first to see that I was getting power to the electrical connection as the middle wire was getting 11.9 volts.

Next I hooked up my vacuum pump to the top barb of the solenoid, turned the ignition to RUN, and then switched the 4x4 selector on the dash to 4WD HIGH. Looking at the vacuum gauge showed no vacuum at all. It should have showed a vacuum of 10 in.....correct?

I assume this means that the solenoid is bad?

 

It's almost impossible to test these on the truck because of noise (electrical activation).

There are two general ways to test:

1. The more difficult way:

a. If you remove the Solenoid - Disconnect Harness and Vacuum Lines, Remove one bolt and loosen the other.

b. Put it on your bench, connect a 9VDC Battery using jumper wires with small alligator clips (+) is the center pin, (-) is either other pin you should here the plunger move. You can also attach a vacuum gauge and draw down to 15 Mg. It should drop off immediately when the unit is powered.

2.Much easier way (and tests entire system to the Hub Assy.):

a. Pull the Vacuum Line from the HUB. Put a Vacuum Gauge on it and rest it on the tire where its easily visible. (If you have two you can test both sides at the same time). Turn the ignition to the Run Position. Activate the 4x4 Switch on the dash. The Vacuum should be between 10 - 15 Hg for about 15 seconds or longer to activate - the important thing here is the Hg and that it maintains.

b. The Release Pulse is less time. Again, the important thing here is the Hg and that it maintains.

If you determine yours is defective, I have a known good one in my shop.

 

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