Hello, all. Been having a rather odd issue with my truck lately. It's a 1985 F-150, only has 65k on the clock. (Hasn't rolled). Been driving perfectly for months now, just the other day I was coming down a straight bit of road after a corner, wheel straight, and there was a sudden whine that you could feel in your feet, then the truck suddenly veered off to the left. Yanked it back and all was well for about a mile, then it happened again. A few days just into town and back and no further problem. It seems to do it mostly when it's first warming up, it's as if the power steering is taking over and trying to go another way. You can turn the wheel over center about 2" and literally nothing happens, then it jumps and pulls you hard to the side. Never seen this before, any ideas?

 

That is a spool valve issue in the PS box ,it almost sounds like debris in the system is jamming it. To start I would flush the system and re fill with new Type F fluid and see if that fixes it

 

Flushed her out real good, was flowing out nice. Drove perfectly for about the first 5-10 miles, then I could feel the 'loading up' while making slight left turns. Way better though. I'll try and run it a bit then flush it another time.

 

4x4? two wheel drive?

 

She's a 4x4.

 

I had this issue years back, Drive fine the pull the wheel right out of your hands and want to go on the sidewalk.

Frozen universal in the steering knuckle. This is what happens, there are 4 caps on the universal. Lets call them North and South (linked together)
and East and West( linked together)
Now North and South are still able to rotate and spin free in the caps. (even with hubs unlocked, the axle DOES rotate some) Now as long as North and South are pointing UP and down, all is good in steering land.......

Now East and West are frozen solid.... as the axle rotates a little, East and West end up in the up and down positions, and this is when all hell brakes loose. Once North and South come back to top and bottom all is good again.
To test the frozen universal theory, With hubs unlocked and wheels straight, get into the universals and rotate them with a screwdriver (as a pry bar) Now turn the wheels to either side and try again, if frozen they lock up.

Another way to test is with tires straight, jack up the front end (both wheels) lock the hubs, then rotate the tires by hand. watch universals, are they spinning ok?
Now turn the wheel to right or left, rotate the tires by hand again, od the tires lock up? Frozen universal.........

 

Ya Run it a bit more then flush it again. Some how you got some crap in the system and it is jamming the valve hopefully it did not do any permanent damage. If the next flush does not sort it out you likely are going to need a new box.

 

Check the front axle ujoints.

 

I will be the 3rd vote for front axle u-joints, I had it happen to my 89 also. What I did was put it in 4x4 and drove it around on some dirt roads, I had a theory that this might loosen the joints up and it did, it doesn't do it anymore. Make sure you drive it around plenty of turns to angle the joints and work them really good.

 

Doing as Franklin suggests can put a lot of wear on your spindle bearing and lockout hubs. A seized joint will try to load them very heavily at odd angles until it has destroyed enough of itself to operate freely, if sloppily. Ujoints are cheap, just replace them if that's the problem. Good time to repack wheel bearings and spindle bearings as well.

 

Just lift front end, lock hubs and rotate tires by hand and now turn the wheel.....

 

Forzen u joints can be an issue for sure but the symptoms in this case do really point to that. Frozen joints will generally be fairly consistent. This one is intermittent. and it improved with a flush indicating debris in the system or a worn spool valve.

Either way it does not hurt to check the axle u joints, The quick and an easy way is to jack up the front of the truck turn the wheel to just before lock (either direction) Lock the hub on that side and turn the tire it should turn freely. Unlock hub and repeat on the other side. Any stiff spots or binding indicate a frozen joint.

 

This has not been my experience. One half of the joint gets stiff while the other may rotate smoothly and freely, the shafts will rotate randomly while the hubs are unlocked, resulting in randomly stuff steering.

 

All the 4x4's I have owned I have never had the axles rotate when the hubs were unlocked. Might have been something specifc to your T case. But this is an issue where the pump was whining even going in a straight line which would indicate the pressure relive valve in the pump was by passing. which would be because the spool valve in the box was cross feeding that can only happen if it is not functioning properly. Also the flush improved/lessened the issue, again indicating it is likely a steering box issue.

If the box has failed in this case it would be advisable to swap both the box and pump.
Replacing the pump is never bad idea when you replace the steering box regardless.

 

Hey, all. Haven't been able to get at the computer. It's definitely the U joints. I always thought it drove funny when they were engaged. Thanks! No idea how I missed that when I had it all apart.