Help! Transfer case problem?

[ssamsom]

I keep my truck in 4x4 on side streets in the winter and shift out on the well plowed main roads. Went to pull out into traffic in 4x4, took off great and half way into the intersection it dropped into 2 wheel drive. Made a loud thump noise but the 4x4 light stayed on.

I switched it out of 4x4 after and back in and it was fine the rest of the day. In the truck's defense I did hit it pretty hard taking off right before it dropped out, but I can see it being pretty dangerous to have the truck drop out of 4x4 when you aren't expecting it.

Should I be concerned? It has never done this before, had the truck in the shop a few weeks ago for a coolant flush and got my mechanic to check the transfer case fluid. He said it was full and looked clean. Any ideas? Thanks in advance guys.

[ssamsom]

[scotty2280]

are your hubs on auto or lock?

[ssamsom]

As far as I know automatic, the truck is a 2005 lariat and I have the electric shift on the fly.

[scotty2280]

my shift on the fly would drop out of 4 wheel drive every now and then. it might have just been a fluke, i now leave my hubs in the locked position. maybe try that.

[ssamsom]

That means the truck will stay in 4x4 full time am I right? Sorry for the stupid question, somewhat new to the superduty world.

[scotty2280]

no only when you turn the switch in the cab. ford was nice and put hubs on there cuz they knew the auto would not always work. the lock on the hub just makes sure the front is always locked in. just remember to put it back to auto during the summer.

[ssamsom]

Thanks for all the help man I will do that, any downsides to keeping it locked for the rest of the winter?

[scotty2280]

nope......