driving on a paved road(some potholes but nothing bad) came to stop sign.
after waiting for trafffic to clear, made right turn onto state highway truck began to pull to left, atfirst i thought i had a flat tire but every thing looked okay.

drove two miles to home, if let the steering wheel go, the truck would change lanes in about 25 feet

02 ford crew cab 4x4 7.3 power stroke 20k on michelin.

any ideas would be helpful

 

Ball joints between Axle and Spindle - one on top and one on the bottom. If you jack up the axle so that the wheel is dangling freely, you can use a crowbar or 2x4 to lift the wheel upwards to see and hear the play.

If you plan to do yourself:
Plan on new seals for the axle shaft, the special tool for the install of the axle shaft seal, lots of pickle forks, ball joint press with the extra kits for FORD Superduty. Lots of good info on the board and in the Tech Folders. You might as well replace the front brake lines while you are there, SpeeedBleeders.

 

Jack the front left wheel up and try and spin the wheel. My guess is a bad wheel bearing or a caliper that is holding on.

Richard

 

Because it happened suddenly, I'm going to lean more towards a Tire issue.

 

Also check the left rear brakes. If it or the emergency brake is binding, it would cause the truck to pull left too.

Did you notice any smoke coming out of either left side wheel hubs?

 

If the outer front ujoint is bound up with rust this will exhibit the same effect. How many miles on the truck? How often do you engage the 4WD?
Put the suspected bad tire on the other side and see if the pull follows the tire.
Agree with checking the BJs and hub bearing etc...Start simple with the tire thing first then inspect the BJs and wheel hub bearing. Then its time to pull it apart and look at the ujoint. Now that you have it torn that far apart let the MAWs commence...Might as Well replace the BJs U-joint and bearing with USA or FoMoCo parts.

 

A sticking brake caliper will make cause a brake smell on that side. Take a couple whiffs for a burning brake smell near the wheels.

 

x2 for sticking brake calipers.

 

Just went through this again for the third time on my LF caliper.

Look for the smoke or smell, that will tell you if a caliper is sutck, either due to internal failure or an internally collapsing hose.

It started suddenly after a stop because the brakes were applied but the caliper didn't relax it's pressure when the pedal was released.

Very common.....

 

Yep agree with this too. Start simple. Look for a hot rotor. Should feel look and smell hot.
Soft brake lines are a perishable service item. They should be changed due to condition, miles or age. Brake fluid should be bled every few years or by mileage. Fresh fluid will keep things alive much longer verses never flushing. Most follow the never flush rule.