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Sunday at the deer lease I had to engage 4x4 in some thick sand. My ESOF did not want to work (of course right in front of my anti-Ford father-in-law) - blew air out the defrost vents so I figured I had a vacuum leak. I got home and was getting ready to order a pair of the knuckle seals I had feared went out upon initial inspection when I decided I better trouble shoot the whole system before going down a long rabbit hole. While trying to trouble shoot, I heard the click at the relays, everything was soundly connected at the solenoid, and the front axle locked as it should this time and then repeatedly afterward in the drive-way. I'm now dumbfounded. Does the intermittent nature of this issue point to electrical? Relay or solenoid? Or could it still be a vacuum leak and I should proceed with a vacuum gauge?
Based on the fact that your air was only coming out of the defrost windshield vent, that is a strong sign there was/is a vacuum leak. I would not consider vacuum leaks to be intermittent, but I have seen stranger things.
If I were you, I would physically and visually inspect and trace each line including the ones in the cab under the glove box. Each line to the hubs, etc... Check the vacuum reservoir for damaged areas.
If you have a mightyvac or something similar you can pressurize the system.
If you don't need to keep the stock hubs, just get some manuals, Your choice of Mile marker or warns. Simple install and you know they are locked without wondering or worrying about all the crap that should make them lock.
If your set on keeping the stock crap, buy a vacuum hand operated diagnostic pump off ebay for 30 bucks. I did and it's the bomb for everything this involves. Easy to use and very nice to have if your staying with stock. I had a cracked plastic elbow I never would have found.
I replaced my autolocks with Milemarker premiums 5 years ago and when I need/think I jump out and lock them and have not been let down. I strongly recommend it.
BTW, if you go with the manual hubs, you cap and terminate the ones that run to the axles and that drops the blend door issue off the problem list as well.
BTW, if you go with the manual hubs, you cap and terminate the ones that run to the axles and that drops the blend door issue off the problem list as well.
JS
I have the ability to lock my hubs manually and that's how I got out of the sand. I hear good things about the Warn hubs. What would I gain exactly over my current stock set up? Excuse my ignorance here.
Thanks for everyone's input so far. I will continue to inspect the lines. What I could easily and visually inspect looks okay so far, but I will dig deeper tracing every bit of line and also try pressurizing the system. The switch works again as designed now, but the little hiccup on Sunday has me wanting to make sure it's going to stay that way.
You will gain exactly nothing in terms of the 4x4 if your auto hubs still rotate manually. The vac issue for the heater is the only gain by disabling the vac lines to the hubs.
If I were you. Invest in a vac pump on the cheap and find out if you do indeed have a leak. So simple to diagnose. You tube has a plethora of videos on this using a hand pump.
The factory setup is really nice..........until you need it and it doesn't show up. It showed up for me a few times and I just got tired of guessing after repair after repair. I just took the 4x4 out of the question and don't mind getting out to lock up.
Some in here live on them because they drive thru mountain passes and need the reliability on the fly. If you don't need that luxury, you can minimize future problems dramatically by just terminating the axle from your vac pump. Leave everything in place for future owner and buy 30 cents worth of caps.
You can visually inspect everything and all may look great to YOUR eye.
If you don't do a vac test on each line and each hub, your the guy running in circles around a super-duty and the neighbors better have a lot of beer and smokes to watch that show.
Ain't happnin. Let's say you have a hub seal breached. The only way your going to visually inspect that is pulling your axle completely down. With a vac pump, you can isolate the exact location faster than I can make a side of ribs.
If you decide to take my advice and grab a vac pump, don't start at the top as everyone else does. Start at the hub on each side and work up. Save yourself alot of time.
I wouldn't do a cheap vacuum tool, I'd get a good one. I have a cheap one, plus I have an air-powered brake bleed kit I bought at Horrible Fright. I want to get a good metal vacuum tool - like MityVac. I used the plastic tool a gajillion times on different projects all around the truck, and it is thoroughly worn out.
When you turn the wheel or go over a bump, you are flexing the lower vacuum hoses. My hoses had weathered ends, and I had just enough hose to trim them back for a fresh connection on the hub fitting. I would look closely at where the hoses are under the most torture.
I maintained my ESOF hubs until they wore out, then I replaced them for no more money than a set of Warns... and they work perfectly.
I'm with Tugly on this one. Why remove a good working auto hub and replace it with a manual hub if the only problem you have is a .25 piece of vacuum hose has come loose. You can still switch your auto hubs to manual engagement, just like the Warn version. When ESOF is working, you can do this from in the cab of the truck.
A vacuum leak is not difficult to find, but it can be if you don't have the right tools to locate the leak.
Thanks Sous and Tug. You both have assisted me immensely over the last year with getting my 7.3 more reliable than when I first acquired it. If you were both closer, I'd buy you guys breakfast in appreciation. Maybe one day I will have that opportunity to let your many words of wisdom fall on my ears firsthand over a cup of coffee.
And maybe some of those ribs Denny is talking about
I don't have many neighbor's within sight of me, but I do appreciate the tips for my own sake.
Here is a quick and simple check without hawking anything to see if there really is a leak.
Key on the truck and run to the pass side and put your hand/ear to the pump.
If it doesn't shut off within thirty seconds. You have a problem. Check out the excelant U-tube tutorials on the esof. If it doesn't run at all, there in lies the problem. You can pull the line that feeds the vac can and your pump should roar. If not, pump went south.
Slightly longer and then it cycles, you have a leak.
As far as a vac tool goes. Anymore, if you order one for 30 bucks on ebag as I eluded to, because you'll use it 1 or 2 times before you tip over. I put mine on a known hold solution, (such as plugging the tube) pumped it a bit to 4 lbs neg and let it sit overnight. If it doesn't leak down, trust it.
Simplicity and not overspending or over-engineering the problem is the root.
I would also say that vac hose is about 50 cents a foot. Don't trim, remove, cut to size and replace.
I'm at a loss to explain what happened Sunday. I did vaccum test the system today. Vacuum holds line up to the reservoir on both sides and vacuum holds in the hubs themselves. The esof switch continues to work and without blowing out the defrost vents. The pump does shut off in a timely manner as you describe Denny. I guess I should just be happy it's working right again but the isolated miss-hap on Sunday sure is baffling. Going forward, if it happens again I'll be better prepared to diagnose the breach. Thanks all.
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