2000 Ford F150 - Intermittent 4WD Inop FIXED!!

[NPASC_mike]

Searched through the board, found the usual answers to this issue, all of which check out fine. The normal things, GEM, solenoids, Vac system, Vacc motor on Diff. All check out fine; 4WD indicators on dash working as designed. Truck is Manual shift and Auto trans behind 5.4L

The only way I can get the 4WD to engage is to jack one wheel up ( usualy the left front) and rotate it to engage the differential. Once I do that, the 4WD will go in and out fine for a day or so, then after a cold soak ( sometimes even as little as 6 hours) the differential quits engaging again. rolling forwards, backwards, has no effect. as long as both front wheels are rolling the same directon the Diff will nnot engage, untill I jack up one wheel and spin it while tring to engage. then works fine again. for a few hours.. Just as it was designed to work..

HOWEVER, this morning, came in a backed truck out, and 4wd is working.. so far.

Has anyone run into this before? Going to send truck back out, it is coming back for more work later and if problem re-occurs, cust said he will have me tear into it further.

Mike Warren
North Port Auto Service Center
Dutch Harbor
AK

[brianp87]

SO are you getting movement on the vac motor at the diff

[NPASC_mike]

SO are you getting movement on the vac motor at the diff

Yes, all the time, even when diff does not engage, the shift lever into the diff has full travel,not like its getting bound up, I took Vacuum motor off and the does not feel like any binding or sticking int he shift lever, and it movesall the way in both directions.

Pardon my typos.. I hate this laptop... ugh

[brianp87]

Theni have no idea. sounds like you have everythign you need whenits commanded but still doesnt theni would request time for frotn diff inspection

[NPASC_mike]

Thanks, Customer needed vehicle, even if only in 2wd, not time to tear down now, just gathering notes for when I do tear it down.

[brianp87]

GL and let us know what you find

[steven kiser]

check vac at differential control. there may be a leak in the system (other than at fork switch) use a vac pump to see if it engages and holds vac. spinning the axle may just be giving this the added ummph needed. you're right at the point of finding the issue. personally i've found vac hoses damaged on passenger inner fender, diaphragms weeping and if this has vac controlled hubs leaks there as well. i've had issues at the knuckle where the steel tube rots and allows vac to escape. DON'T REPLACE THE HUB if this is the issue. what i've been doing is drilling out the tube, tapping the hole, installing a brake line adapter, then bending a brake line to fit. i had a drawer full of the bevel inserts that would come with reman master cylinders but ran out so i use the adapters to fit the line to the hub assembly. if there is a vac leak in the system and can't be easily identified, using a pressure control pressurize the system and spray soapy water around seals. you may have a system that is full of small leaks and finally had enough to cause it to fail. double check for any and all leaks. personally i'm surprised this system worked as well as it did. being from new england i'm accustomed to vac issues as well as evap fails that you wouldn't see in salt free zones. install a vac gage at the manifold where the vac feed attaches and see in there is a variation in the gage when it's switched back and forth. it may just be a fluctuation and not a flat drop. if the needle starts jumping back and forth even slightly you have a leak. it can be anywhere in the vac system. i've had more than a few cracked vac reserve bottles.

[NPASC_mike]

Thanks Steve, Been all through that as I first suspected a vacuum leak not allowing the motor to fully engage, but the shift fork has full travel, I grew up in New England aslo( dont ask me how I ended up in AK) so the corroded lines were the first thing I looked for, No Vac, hubs on this truck, I'm leaning towards something just being gummed up inside the diff, trucks a rental vehicle so it had to go back out in 2wd. Will tear back into it before the snow flies. Thanks for everyones input, Will post what I find after teardown.

[steven kiser]

good luck. there really isn't much there though so it should make it fairly easy to see. unless some other yahoo has been in there before you and installed the fork backwards. thanks for posting the fact that you're waiting. a quickie here, is there sufficient vac under a load to have the interlock work..........

[NPASC_mike]

Yes there is. (sorry for the late reply, been a little busy) I am probably not going to tear into this until late summer. The truck is part fo a rental fleet and back out in service now, but before winter sets in we will get into it. And yes, someone has been in there before, so what you said may not be too far from the truth. lol

[NPASC_mike]

Fixed.

Snows coming soon, so we tore into it. Fork was not installed correctly. Don't ask me how the other guy got it in there like that . The vacuum motor was not strong enough to overcome the added forces from the misalignment. Thanks for the replies.

[brianp87]

Nice

[steven kiser]

so there was a yahoo issue here isn't it just great when not only do we have to deal with normal troublesome failures then you get some help along the way.

[NPASC_mike]

so there was a yahoo issue here isn't it just great when not only do we have to deal with normal troublesome failures then you get some help along the way.

And I thought I was the only Yahoo here... This is not the first instance of this type of issue out here... Guy brought me a Suburban a few weeks back... his "mechanic" has had his truck for 7 months over a no start condition.. They have thrown everything at this truck.. even a new (50k used) ENGINE! still no start...

2 hours, One starter and one distributor cap later... customer drove truck home. Original issue was the starter...

I get one or two of these a week. YAY!

[steven kiser]

i'm a jasper dealer and they'll have vehicles towed in for warranty work. you'd be shocked at what i see. right now i have a box truck on the lot with 33k on it. it's had a ford reman in it, lasted 10k, a jasper unit in it that lasted 800 miles. i slid under it and saw an in line tranny filter, old as moses and installed backwards. cut it open and it was full of metal. where the transmission line came over the sub frame it looked like someone had pried against it, it was pinched. i cut it out and water would just dribble through it. pan was pushed in and you can see that it was caused by a floor jack. the front y pipe had been cut and is loud enough so i thought the muffler was bad. the welded seam looks like a 5 year old did it. i spoke with the owner and he asked me to take a look at a few other issues. it was pulling left and there's a wandering issue on the highway. it had been looked at by his regular mechanic as well as the shop that installed the jasper unit. it only took a few minutes to see the l/f caliper was blue and there was a broken rear spring. i told him it needed front brakes, calipers, flex lines, rear springs, shocks, and possible rear brakes. this is one of those times where i start to get that "what the ***** is going on" feeling. the one where you're going to be the shop that has to resolve everyone else's fubar's and be the one at the bottom of the ladder where the owner finally snaps and takes it on you. i suggested that the truck be towed back to the shop that installed the jasper unit. man you would have thought i asked for his first born. he picked this shop because of their claim of quick turn arounds. he was in the middle if a big job and all his trucks were running 12 hors a day seven day's a week. it took 5 weeks to get the truck back............... even though i've been around since, well along time, and seen a lot of hack jobs, on occasions like this i'm still floored. this is a reason i'm all for requiring a level of certification, but will that really stop shops like this from operating, probably not. all that will happen is the honest shops will get more rulers and regulations to stymie them while the hack shops get busier because we'll have to raise our rates to afford government intervention and insurance increases because of liability.

[brianp87]

Im for the ceritfication if it is enforced. But if not then no. There has to be someone to protect the people from that crap but there is nothing or no one to enfoce it sadly

[NPASC_mike]

Amen Steve... wow. I am sure we have all at one point or another been in the same boat.

There are a few techs out there that may not have certs. but are great at what they do. I wont take anything from them, unfortunately, there's more "parts changers" out here than anything. Its up to the shop owners to determine what their techs capable, or not capable of.....

I value my rep too much to A. let something go out of here that just isnt right. Even if it means I lose a buck or there. and B. Let someone else ruin it for me.

[steven kiser]

i'm not wanting to move this post from point but i have to add one more ditty. the owner called me yesterday and was amazed that given the circumstances jasper was going to cover the unit (he said unit) but not the labor. he said that the shop that installed the transmission was going to call me and explain what happened and that he had fired the tech's at his shop for shoddy work. i told him that there was absolutely no reason i should be called and really didn't care. he also informed me that the brakes had been done at his local shop last year (with a reman transmission) i told him that it would be better if he towed the truck back to one of the prior shops to have the work redone. he felt that since the work was shoddy it would be best to have me do the work. he investigated my shop yadda, yadda, yadda. he added that the shop that installed the transmission said that one reason for calling me was "to work something out" about getting paid. no way was my reply. they could refund him but i was to be paid by him upon pick up and would implement a storage fee three days after truck is completed, the exception would be if i called him friday afternoon then the count would start on monday. all i can smell is law suit or better business bureau and i'm not going to be caught in the middle. i explained that i sided with him about the shoddy work but wouldn't allow myself to be added to the mix. i said that i would have to approach this as a hostile witness and would require a certified bank check from a local bank made out to me personally (that way i can cash it instead of depositing it, if it were made to kiser automotive it would have to be deposited. i make copies of the check. cash it, deposit the cash into my bank, take the deposit reciept, make a copy, staple it to the copy of the bank check and file it incase i need to prove it was deposited into the company account) i know that i'm protecting myself by following these basic rules but i still feel like i'm doing something wrong. go figure, this guy gets bent over by other shops and somehow i feel it's my responsibility to fix all wrongs. i even tend to cut people that are in these situstions brakes because i feel bad for them. i have to keep reminding myself that it wasn't my shop that did the shoddy work and to stop acting like it was. if the reversed fork was in my shop i could see myself cutting the customer a deal because he already paid to have it repaired. i guess i'm old school and put myself in the customers place at to deep of a level. i really feel bad when i tell a customer that the only way i'll repair an issue from another shop is to remove all that they installed and install my parts. it's a prudent move since i know that once i work on it the shoddy shop is out of the loop but since i know that the customer probably isn't going to get anything from the shop i feel bad and it really works on me. well enough.................................

[NPASC_mike]

This could go on and on...lol Where we are in AK, there are not many options for repairs. (two other shops on the Island.) People here are used to bringing a vehicle in, and maybe in a few weeks they will get it back. Maybe the issue will be fixed, if even looked at. Estimates? HA! They would always pay because they really had no choice.. was it fixed correctly? oh well, if it wasn't they would pay AGAIN to have it fixed. Working very hard in the last 7 months to change that here. SO far so good. I'm charging no different than if I was in Upstate NY still. and people say I am too cheap. In 7 months I have had one comeback.. and it was a part failure. Its a good feeling when your in line at the grocery store, and you overhear someone talking about "the new shop in town" and its all good things. Nice to know there's still some honest people out here doing whats right... but like you said... we are the ones who end up paying for the half baked places.

ANWAY, have we vented enough yet? HAHA Thanks again for the responses. Wealth of info in here.