4WD auto locks not engaging
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Junior User
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4WD auto locks not engaging
2008 f350 180000 deleted not that it matters. Think I have a broken vacuum line somewhere, Good vacuum pump and new 4wd solenoid and good seals in the hubs, but still not auto engaging, works great if manual locked, and worked great until I had to have the cab lifted and the exhaust manifold studs replaced. Any idea to where to find the possible leak or would it be best just to replace ALL lines to be sure? Yea I know that's a stupid question, but should I go back with plastic line or rubber in your opinion?
Thanks
Thanks
Cargo Master
Joined: Nov 2005
Posts: 2,768
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From: East Tawas, MI
Mine failed at the drivers side just where there is a scimpy 90 deg elbow that turns down directly after the pump. (a quick disconnect fitting that helped itself)
If they are pliable and not brittle, no need to go all in on full replacement. I suspect you have a vac tool with a gauge, if not rent or buy one. They are dirt cheap and should be sold with each truck...lol
Does your pump cycle off after 20 seconds or so and how often does it run with koeo?
Denny
If they are pliable and not brittle, no need to go all in on full replacement. I suspect you have a vac tool with a gauge, if not rent or buy one. They are dirt cheap and should be sold with each truck...lol
Does your pump cycle off after 20 seconds or so and how often does it run with koeo?
Denny
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Mine worked fine until the cab was lifted off. then found the line by the passenger side battery broken so I replaced it and guess the rubber line I used didn't ever get it quite right, sometimes it would work and sometimes not, now it wont at all, the pump ran like forever after I replaced the 4wd solenoid but finally went off, cycles on just a bit when the 4wd is turned on then goes off but still nothing , so I know I must be missing something somewhere and don't want to "Band-Aid" the issue. and vacuum leaks can be a bear to find so that is why I am thinking of a full on replacement of all lines. after that their cant be much else to fix
Hotshot
Joined: Jul 2013
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There are 4 seals in the hub for bearings and such as well as there needs to be a tight fit on the abs sensor, vacuumed gitting, AND ...the tie rod on the bottom of the hitch b...mine Leah’s from there.
i already replaced everything and did a leak test with some hub oil and mine was leaking from the tie rod.
i already replaced everything and did a leak test with some hub oil and mine was leaking from the tie rod.
Lead Driver
Joined: Mar 2004
Posts: 5,372
Likes: 108
From: Northern Indiana
I personally think this is a terribly designed system. Nice when it’s working but not worth the effort and money to keep working IMHO. I just get out and lock the hubs, switch on the dash and don’t look back. I wish I had the floor lever like my old truck.
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I hear ya firefighter. I love the truck over my old dodge but did like the manual floor shifter. I have traced the lines down to where it goes down by the front right shock and that is as far as I got, so the leak is somewhere past that point. going to get a vacuum tester tomorrow and will update yall when I find it and what I had to do.
thanks again
thanks again
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Lead Driver
Joined: Mar 2004
Posts: 5,372
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From: Northern Indiana
Like Fritz said there is a bunch of seals in there. My trucks previous owner much have really wanted it to work as all the seals and bearing was siliconed in there. Guess what.....still didn’t work.
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Hotshot
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running mine as pure manual.
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Hey I think I found my issue, or I hope I have. finally broke down and bought a vacuum tester since I have been chasing my tail like my dog who is laughing at me I am sure by now, its in the right hub, so I took a chance and removed the 3 hex screws on the outside where you can manually lock the hubs in and pulled the unit out and just as soon as I did there is a orange seal oring right there at the lip and sure enough it was way too big like something made it enlarge,, well I tried putting some grease back on it and "tried" LOL to put it back in which it did go at first until I put the tester back on it, It held vacuum for like 30 seconds then I herd it pop and there goes the vacuum, Those seals come in a service kit dorman offers part #600-249 which can be found at rockauto or amazon, Now not sure yet if that is my issue but pretty sure it is so I ordered a kit which services both sides and comes with all O-rings and bolts and seals, so now I wait till its delivered and will try it out, and will let ya know what I find.
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Ok guys so far so good.. I installed my hub service kit this morning and re vacuum tested all my lines and found a bad line going to the right hub as well. So replaced that and everything is working perfectly now.. Should something change i will update all of you. Hope this was helpful to someone
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