Hello. My trucks 4 wheel drive aint working anymore. When i put it in 4 i hear the clunk but there is no power output to the front tires. I get under neath the truck and the front axle spins free. Put it in four and the axle locks. So apparently the problem is with the front differential somehow. Any tips and ideas on what to look for?

 

Read this thread. https://www.f150online.com/forums/sh...d.php?t=293031

 

I lubed the shaft of the vacuum actuator on the diff. and it is working again.

 

I logged in today for the first time in a while and right off the bat saw a post (this one) that seemed relevant to my problem: no Front wheel engagement.

I can't recall the last time it worked, but I think it was last winter sometime. Earlier this year someone gave me some steps to follow and I am pretty confident the transfer case is working correctly: When in 4 H or L the front output shaft cannot be turned by hand; while when in 2wd it can be.

I tried to get some additional info from my Chiltons book...but they aren't what they used to be. Seems everytime I got to it, it doesn't cover what I want to know....look like I may as well use it for azzwype....(rant off)...

Anyways...

I had my son flick the electronic 4x selector from 2 to 4h and I could feel clicking in the solenoids...and from other descriptions at this site.. the pink and blue hoses..I must have the right ones.

OK, so...I'm laying underneath the truck and I see where 3 hoses connect up to the vauum motor or whatever you call it...but what do I do now? How do I test the vacuum? what values am I looking for? Do I disconnect all of them, or just one of them, and what is the big black hose for?

I also read that some guys did this job themselves in about an hour. Well I'm sure I could scrape together and hour if I know what to replace or do....

Someone in this thread also mentioned lubricating the vacuum motor shaft. What's involved with that?

When doing this kind of work are there any gaskets that need to be replaced when parts are removed? Do I have to worry about fliud leaking out if I start disconnecting things?

Thanks for the read...
Steve...currently in 2wd mode
...in Huntsville, Ontario

 

minimustang: The big black hose is a vent hose for the front axle. There are only two to the actuator/motor/diaphragm ( whatever term you prefer ). When in 4WD there should only be vacuum on the blue line, in 2WD only on the pink line. If you have a vacuum pump available it makes the job much easier. If not, apply human vacuum. It really takes only a small vacuum for the actuator to work. You only have to determine if the lines are leaking between the solenoids and the actuator or if the actuator is bad or stuck due to mud/corrosion/etc. No gaskets or fluids involved. Re-read the links posted above.

 

O.k., so the big black hose I don't need to worry about

So if I read what your saying correctly, I should be able to hook a vacuum gauge up to the solenoid where the blue hose is and get a reading and compare that to a reading at the other end of the hose...the front differential end. Luckily I have two of those gauges so I could put one on each ( the blue and pink hoses) and watch what happens, correct?

 

Connect the vacuum gauges to the solenoids to be sure vacuum is passing through them. If so, apply a vacuum source to the pink and blue lines, one at a time, it should hold the vacuum applied. If it doesn't, disconnect and plug each line at the actuator on the axle and repeat the vacuum application. If the lines hold vacuum, apply vacuum to each side of the actuator, separately. If vacuum holds, then the internal shift fork must be the problem.

 

Well I had some time this morning...

Using a Sun vac gauge I tested both the pink and blue soleniods. Both solenoids appear to work: a distinctive "click" can be heard and the vacuum gauge swings to about half scale and stays as long as the truck is running, or until switched from 2wd to 4wd...or 4WD to 2WD depending on the solenoid tested, so I'd have to say the solenoids are working.

Hooked the vac gauge up to the hose and the reading was about the same at the other end of the hose as it was at the solenoid. I believe I'm getting enough vacuum to operate the actuator.

I had my son switch between 2WD and 4WD and I could press on the shaft to move the actuator, but it didn't seem to want to move on it's own. If I had to describe it, it acted like it hadn't been used in a while. Naturally I knew it wasn't working and it HASN'T been used since earlier this year. After cycling it a couple dozen times and helping it along until the boot was fully compressed, it moved only slightly more freely, I still have to force it - by leverageing athe plastic handle of the screwdriver between the pumpkin and shaft) so that the boot along the actuator shaft was compressed. It seemed to want to extend (I think this is 2WD mode) but very slowly and I don't believe to full extension.

I did try to move the truck a couple time after moving the actuator manually...hoping I'd hear the front end try to lock up, but perhaps I didn't travel far enough..the front end didn't seem locked. As mentioned previously I've tested transfer case, and it appears to be funtioning correctly.