I really dont want to beat a dead horse but i still cant shake the thought that the pull i feel is the roads. It seems to do it on every road the more i drive it and the more i keep and eye on it. I even put my summer tires on, stock size General Ameritrac. I put 35 psi in them and drove it for the past two weeks or so. The pull to the right isnt as bad as it was with my ATs on but i still feel like i have to keep a slight constant pressure to the left on the wheel. I have fixed my brake problems and checked everything else out up front. Everything is fine. and have had 2 alignments all say are in spec. Its a 2004 F150 STX 4.6 4x4.I decided to check the IWE soleniod and lines and the IWE itself with my vaccuum guage since i cant find any play in the front. Thinking that maybe if the passenger side was engaging or partially engaging that it would pull it to the right. Am i correct in my thinking there? So tonight i got my vaccuum guage out and checked the IWEs at the wheel, they both hold vaccuum fine. I checked the hose that connects to the soleniod and runs to the intake. That has vaccuum. I pulled the line off the hub on the drivers side. When the truck is on it builds vaccuum (should it slowly build vaccum or should it be an instant vaccum?) I tested the line at the passenger hub and it doesnt not build vaccuum at all, if i try to create vaccumm with the pump on the guage and it wont. Should it and would this be right? I blew the lines out to make sure there wasnt water to dirt in the lines and test both ends again. Same result. So should there be building vaccuum or instant vaccuum at both lines? I would think. But is it possible that there could be vaccuum at the drivers and none at the passenger since the lines are connected? So now, if what i tested is not testing correctly, should i be concerned about the soleniod or the line? If the soleniod, i can get one at the dealership correct? And if its the line, how would i go about replacing just the driver side because of the Y in the line, and what is the way to replace the line, can i build some sort of line with hose from the parts store and some connections, or do i need to get it at the dealership. If thats the way it should be then i guess there is nothing wrong. I know i seem like i hunt for something to fix but to me it just doesnt seem quite right you know. Everything else checks out fine. Wheels spin free now from the brake problems i had, no play from what i can see in the front end and everything is tight. Let me know what you guys think now. Thanks again! One more peice of information. When the front wheels are off the ground and the truck is running while in 2wd, and i spin the wheels the half axles going from the hub to the front diff spin as well. From what i have been reading when there is the correct vaccum with the engine running the hubs should be disengaged and the axles should not turn, am i right there? If i engage 4wd while the truck is running the half axles still turn but i feel more resistence, (like its also turning the front drive shaft). So after saying all of this im thinking that maybe my IWE soleniod is not giving the right vaccumm to disengage the 4wd and its always engaged, and that is why with absolute no vaccum to the passenger side its aways engage, and partial to low building vaccum on the driver side its sometimes engaged and sometimes not. After that it would give me some pull to the right when the passenger side is grabbing and straighten out when they are both engaged. Sound like the culprit?I have also added this to my other post where i was trying to pinpoint the pulling problem with the brakes.

 

If your alignment does not have about .9 degrees less caster on the left side compared to the right side measurement then it will drift to the right.

 

Ive moved past the alignment issue, the issue with the vaccuum with the IWE is what im questioning. I dont think the alignment is the issue now.

 

Can i just make my own new vaccuum lines that go from the solenoid to the hubs? Just put a Y in it to split it off to go to each wheel. Im thinking of ordering the solenoid today from the dealership and then i would have it tommorow. Then replaceing the lines tonight. Then between the two i should have found the cause of little or no vaccuum. If i make my own line out of new hose is there anything i should be careful of to make sure i keep or do a certain way, thanks again!

 

Just called the dealership they have the solenoid in stock at $28, so im going to pick one up after work and give it a try, if that doesnt fix my vacuum problem then i will know its the lines. My solenoid on the truck is one of the ones that doesnt have the rain sheild on it, so i guess it could be shorted out, but i know it doenst have water in the line, i checked that last night and found none.

 

Ok, here is the update, not how i wanted it to go, but when does it ever? i went ahead and changed out the solenoid just because it is the updated one with the rain cover. I checked vacuum at different places, solenoid, hoses at wheels, and the fitting at the actuator. I had good vacuum at the solenoid. I found a crack in one spot in the lines, but that was the least of the problem. I checked the actuators, passenger side i can build up and hold vacuum. Driver side actuator i cant, so guess what, im going to be changing the actuator at the drivers side. Not what i want to do. But here is what i found. Because of the actuator not taking any vacuum it wont let the whole system take vacuum so both side stay continuously locked in which from what i read is better than one side or both sides trying to lock in and grind and what not. So i made a new line going from the soleniod to both wheels, i put a T in the line and took one line to each wheel. I took the old double line at the wheel and used a razor blade and split the big line from the little line so i could reuse the little breather line. I cut out the old vacuum line where i could since im not using it. After i ran the new lines i plugged the line at the wheel at the driver side cause the actuator is not taking vacuum and then hooked my guage up to the passenger side wheel and turned the truck on. It built vacuum and held it so my system is tight and working. I then put the line back on the wheel on the passenger side and hooked my guage up to the driver side hose and turned the truck on, it built pressure and held. So my hoses are good and the passenger side actuator is holding vacuum. Before i did all of this i jacked up the truck and spun the wheels just to verifly what was moving with the truck on. Half axles are moving as well as the front drive shaft. When i applied vacuum to the passenger side actuator and spun the wheel only the wheel spun, so that made me feel a little better. So the dealership has the actuators and i should have grabbed one while i was there just in case, but i didnt so ill pick one up tommorow on my way home from work and put it in tommorow night. Im just really convinced now that all that extra rotating mass is giving me my vibration and possible the wandering of the truck. Its just not the way i wanted to spend my friday night. So now the question is what is the best way to get the actuators out? I have a good idea, but what all do i need to do and what is easiest? Do i need to take the spindle nut off and then do i need to get a new one? Thanks guys!

 

this may help you.
http://www.f150online.com/forums/200...replacing.html

 

Thanks for the link, that really helped alot and cleared some stuff up.

Ok, i took work off today to fix my truck cause it was bothering me. And i replaced the driver side actuator already. Not to hard to do after i read a couple posts here and ther on how to do it. And the driver side was deffinately shot, the seal/boot around the actuator was all ripped. I put the new one on and checked the vacuum, it holds, so the vacuum leak is fixed. I will post pictures later cause my computer is going on the fritz. I picked up two of the actuators cause i figure i might as well do both cause i know as soon as i fix one the other will go. So im off the to do the other side. Thanks!

 

good job so far my friend,let us know how truck gonna drive after you replace actuators.
if you don't mine asking how much the actuators coast? i may have to replace my actuators too.

 

I just finsihed the passneger side and it went smoother than the driver, probably cause i knew what i was doing after the first one. After i was done i started the truck and spun the wheels, and only the wheels turned! YAY! The one i took out of the passenger side was still working so i plan to hang onto it just in case. Im going to take it for a ride here in a minute and see what i feel.

The actuators at my dealership were $103 a peice, ive noticed that my dealership seems to be a little higher priced than most, but i wanted to get it done and they had them. i think Y2KFordParts has them for alot cheaper if you want to order them online. If i wasnt in a hurry to do it i would have ordered them there, but it takes about a week for me to get stuff from them cause of the distance between.

For those you wanting to do this, and have tore parts off the front end of you truck before, its cake. And the link above that you posted has a link to the repair manual procedures towards the end, and you might see a post in there from me as well. Thanks. Ill let you guys know how the drive went.

 

Ok, not so good. I went for a ride and when i get in high RPMs and the vacuum drops (from what i read about the RPMs and vacumm) i can here one or both actuators trying to engage. So i let off and it goes away so i kept out of the gas on the way home, only drove a couple miles. So i checked allthe vacuum at idle. I get 19.5 from the intake, and at the hose ends at the wheel. Everything pumps up and holds vacuum, all the lines and hubs. I cant tell if both hubs are trying to engage or one of them. i might be tearing this thing back down and check that i put everything back together ok the first time. Any thoughts.

I also was blowing out some of the lines that i left on the truck and while blowing out the one line i heard a loud pop. So i pulled the battery out and the battery tray and found a little black box that is connected to the vacuum line coming off the intake, it Ts off right below the solenoid. So i pulled that out and what happened is the seem blew apart. So i bypassed that box and the line coming off the intake goes straight to the solenoid on goes to the solenoid and one to the black box, im guessing its a vacuum resivour(sp). This all happened after i drove the truck the first time and came back, so i know that didnt cause anything. Is it ok to bypass that vacuum resavour(sp) box. i get instant vacuum for the wheels now instead of it building up. Thanks.

 

ok, im ruling out that i put something together wrong, i just took it for a ride and with a long hose running into the cab to my vacuum guage and the pressure is dropping too far during load and high RPMs like going up a hill. All my hoses hold vacuum and i tried both solenoids that i have. Where is the vacuum? What else should i be looking at that could be causing low vacuum at the engine? Thanks!

 

Ok i expoxied the vacuum box back together and it holds 20 psi. I put it all back together and took it for a ride. It was much better. I only had the whine noise of the actuators once. As i watched the vacuum guage in the cab that i ran a long peice of hose from a T i put in the solenoid to wheel line, i could see as the engine went higher in RPMs and under load the vacuum would go down. At the point where i got the whine, i went from a dead stop and up a constant incline. Thats the only time i got it, but the vacuum fluctuated alot during the entire drive so here is my question now.

There is a check valve in the line coming off the intake, that line T's off and one end goes to the vacuum box and the other to the solenoid. If that check valve isnt closing completely will i see the constant change in vacuum from the engine. If so then if it was working correctly wouldnt it let the vacuum box build up with vacuum as with the lines to the wheel and hold that vacuum unless the the engine vacuum increased or there was a break in the system from the check valve to the wheels? Because here is what i found.

I pulled the check valve and sucked on the ends (keep it clean guys). The vacuum side i could freely pull air through. The other side i could still suck air but it was restrictive. I had another check valve in my tool box but the wrong size. When i sucked on that one i could freely pull air through one and not the other at all. This leads me to beleive that the check valve is only partially working and im seeing the fluctuation of the vacuum from the engine in my guage and every now and then its dipping down to the 5 lb mark and that is where i get the whine.

So now after i have fixed everything else in the vacuum system a little check valve which i beleive to be worn out is standing in my way. Do i sound like that is what is going on? I hope someone is reading this stuff cause no one is responding its just me rambling, but this may help someone else down the road.

 

I replaced the check valve, took it for a ride and it went good for the first couple miles then the vacuum dropped again and started fluctuating again, so i went home and checked the check valve, it was ok, but then i found another check valve in the same supply line but up by the solenoid, i pulled it and it was completely shot, free flowing air both ways, so i went back to the parts store and got another one, put it in and took it for a ride, it went very well vacuum stayed up and it did fluctuate a little but only a few lbs here and there, im attributing that to the equalizing of pressure in the lines and that is allowing it to drop. But when i would get on it the pressure wouldnt drop too much, maybe a half a lb. I did notice while criuising on the highway that i had a constant slow leak down in pressure, never went below 14 lbs during the couple mile stretch i was on so it didnt hurt anything. So i went home again and checked the vacuum box and it isnt completely sealed i guess, i still get a slow leak down so i put more epoxy on it and im going to try it again. Good thing i have one on order. I think that is my problem now and im pretty confident that when i get the new one all my vacuum problems will be fixed. This vacuum stuff is enough to make me want to pull my hair out!

 

If all of this rambling helps one other person than its worth it. I think there could be some other better option for the 4WD system than a little vacuum line.

When i took it for a drive when the system was working, the pull was gone, i still got the crown in the road pull on certain roads, but the constant pull is dramatically decreased, i wont be able to tell for sure until i get the system completely fixed and am able to drive it for a couple days. The steering wheel is more free, the truck feels like it has more power. The truck drives smoother, and quieter. Its going to feel like a completely new truck. I just got the truck last June and this is my first ford truck. I always have felt like during normal acceleration that something was holding my truck back, i always had to mash the gas to get it to go on normal acceleration. But now i can attribute all that to my truck in a sense "pushing" the front tires to turn all the front driveline components. Maybe thats why it seems like my ATs are so noisy. I took them off for some regular tread. Ive also read that when the driveline locks up like this that it could decrease the gas mileage by 2-3 mpg, if that is true, i got 16 mpg on the last tank during my normal driving around, i could possibly get 18-19 driving around town with my 4.6

The more i think about it, what is the vacuum box actually doing anyway? I know it hold a reserve of vacuum, but there are two check valves in the system one on each side of the vacuum box, so what ezactly would it hurt if the box was taken out? i know i did it before and it didnt work, but that was before i found out my check valves were shot.

Im going to draw up a little vacuum line diagram to show all you guys the whole system for those who havent looked into it.