Help please. 1998 4x4 f150 When I shift into 4 wheel drive (manual shift) everything works fine ,light comes on, front drive shaft turns,vacuum actuator on front dif. moves but heres my problem sometimes it don't seem to move in far enough and it does't engage but if I go under and pry it over even just 1/16 of an inch it will engage. I'am taking here vacuum actuator. And also sometimes if I torque it to much like turning a little to harp the front wheel will disengage. I check the actuator and the diaphram don't seem to leak so as the vacuum lines. Any ideas. Could it be worn inside. This truck was never abuse.I only use it to go to work and I only use the 4 wheel drive when the road is slippery in the winter .I have a Haynes repair manual but they don't show any part of the front diff. Would some one know where to get reading material or graphic of the front diff. Talk to Ford about it and they say it could be the fork inside that is bad.
By the way I also had a lot of electrical problem with this truck and after reading the forum I learn about the leaking windshield and would you believe that I replace it and it fix the problem. Thanks Guys. Coming back to front diff. does any one ever change this fork . Do you have to take the diff. out? I presume this so call fork is moving a collar or something to engage. I would like to see how is't made inside, so if anybody have picture I would appreciate.

 

Hi papp and welcome to the forum

I dont have a good picture of the guts of the front diff but I'll look for one.
There is a shift fork inside that could be worn. The fork does move a sliding collar.
To open up the diff you have to remove it which is actually not all that hard to do. Opening it up to see what the problem is isn't too hard either.
I dont have time to go into much detail right now but if you decide to tackle it and have any questions feel free to ask.

 

Thank you racerguy for the info. I don't think I will tackle it right now because I don't have time but I probably will this spring when the weather warms up here in Canada. In the mean time if you find some picture send them. Your right I didn't think it was that big of a job to do but I wasn't sure if the problem was inside or just the actuator. Thank you again

 

What do you mean "when the weather warms up here in Canada"?
I'm in northern BC and it hasnt been below freezing in almost 2 weeks now

 

It has been very cold here in N.B. We had -36 C one mornning and it stayed cold for a couple of weeks. Little better now.

 

It's supposed to freeze and maybe snow a bit again this weekend. It will be a nice change from the rain