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ESOF frustrations...

2K views 16 replies 7 participants last post by  Firefighterwill234 
#1 ·
So, tinkering on my new to me 2004 F250 XLT CCSB yesterday, while checking some gauges on TorquePro I decided to activate the 4wd and was greeted by my A/C switching to defrost. I had already done a little reading and knew that indicated a vacuum leak to the auto hubs. Feeling around I could tell the right vacuum line was intact but deteriorated so I was pretty confident it was an easy fix.

This morning I picked up some replacement vacuum line (actually 3/16 fuel line) and crawled under the truck. Right side line pretty much came apart in my hand. Got the old stuff out and decided to see if the hub holds vacuum. Connected my mighty vac, gave it a couple pumps to about 7-8 in HG and let it sit. Decided to replace the left side line at this time. When I was done removing the old line and getting the new one on the left I checked the pump, still holding vacuum. Finished off the right side connections and checked the left hub. It also held vacuum for about 10 minutes so I finished off the left connections.

Thinking I had this whipped I started the truck, turned the A/C on and then activated the 4wd. Immediately the A/C switched to defrost. I checked all of the vacuum line connectors, everything seems like solid rubber. I suspected that maybe one of the hard lines might be cracked but decided before chasing that I decided to check the vacuum coming off the PVH.

I connected my pump/gauge where the line from the PVH makes the first connection rather than try to get the dual connector off the solenoid. Once everything was connected I hit the 4wd switch and again the A/C switched to defrost. Since everything but the PVH was eliminated for this test I have to believe the solenoid itself is bad. That or the hard line between the solenoid and first connection now that I think about it.

What are y'all's thoughts, am I on the right track?
 
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#2 ·
So, after posting my question it dawned on my I could check the hard lines with my hand pump. Good news, working form the first connection I was able to pull and hold 15 in HG for an easy 10 minutes. I think the hard lines are good to go. Then I did a quick google search, looking for part pricing and that search pulled up some older posts here, father back than I was manually going, which discussed the very same issues (to include the tests I had done). I am pretty sure the PVH solenoid is toast.

From the older posts it also appears my best bet is OEM. Good thing there is a Ford House in town.
 
#5 ·
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#7 · (Edited)
NIce, I'm poking around in the vendor forum now.

I have inquired about the part number from Sunrise, in their system 7C3Z-9H465-A does not show to fit my truck. Price is good and their facility is only 30ish miles away. Should be pretty quick shipping too. Just waiting for the answer on the part number.
 
#9 ·
ANWBL is in Minnesota. :poke
 
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#12 ·
just in case you didn't know

the dash lights only confirm the transfer case has done what it is supposed to
there are sensors in the t case to verify shift fork location

there is no way for the system to verify if the hubs engaged

that is easy to check by reaching in to the axle knuckle and seeing if the axle shaft will spin on either side
 
#13 ·
True, plus there is also distinct feedback through the steering wheel when on dry pavement.

Axles did not turn in the knuckle while parked and engaged, short drive on dry pavement allowed me to feel the feedback through the wheel.

Sure beats finding out the system is inop only after getting stuck...like I did in my '78 F250. Bought that one used in late 1980 and promptly got stuck, requiring a tow truck to unstick me. Come to find out the right hub was inop. Looked to have had a leaky seal, filled the hub with water and did bad things. A lot of cleaning and a replacement spring and a couple small parts and the system was fully functional.
 
#17 ·
Solenoid should be near the battery box on passenger side. youll see a large vac canister also, on top of the fender

My F250 did this to me once in the middle of a snowstorm. Its been a notorious issue with fords that have the auto hubs. If for whatever reason you cant figure it out, i highly recommend the Mile Marker 449SS Manual hubs, if you wanted to go that route. Personally, i disabled all the vac nonsense on mine and converted to completely manual, kind of a PITA at times, but its nice knowing youre fully locked and ready for action
 
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#15 ·
The solenoid is on the right fender, near the battery



It is the white box looking piece right by the corner of the battery.

I would check your vacuum lines to the front spindles first before jumping straight to the solenoid. Then verify the hard lines between the vacuum hoses and solenoid haven't cracked.

In my case the rubber vacuum hoses has deteriorated badly but replacing them did not cure my problem as the solenoid had crapped out.
 
#16 ·
This guy can explain it better and a whole lot quicker than I can type :grin:



-jokester
 
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