Truck Repair: F-350 front hubs, ford f 350, vacuum lines

Question
I have a 2001 Ford F-350 Lariat ext. cab 4 X 4 with a V-10 and auto transmission.  I ordered the truck with the optional shift-on-the-fly vacuum operated auto locking front hubs.  While on warrantee, I returned the truck to 2 different dealers because I was having trouble with the front hub locks.  The first time (Dec, 2002) the dealer said they fixed a controlling vacuum line that had melted.  The second time (April 15, 2004), both front hubs we supposedly replaced.  Recently, I found that the hubs will only lock when I manually lock them- not when they are in the "auto" mode.  I only use the 4 wheel drive feature accasionally during the non-winter months.  Now that the truck is 4 1/2 months past warrantee, I am wondering what I should check to trouble shoot the problem.  I have looked for the obvious- melted vacuum lines, etc. with no success.  Do you think the second dealer may repair it under warraantee as a pre-existing condition?
Thanks,
Jack

Answer
Hi Jack,
I would talk to the dealer where I would reasonably expect to someday buy my next truck, and explain to him that you are dissatisfied, and could he help you out. He can check on recalls, service bullitens, service campaigns,(which are like recalls, except they don't contact you...just repair them if you have a problem), etc. That is awful close on the warranty, and he could probably do something since you have had it in for problems.

Blown fuse, vacuum control valve, switch...all are possibilities you could check, to answer your question.

Keep in mind, and possibly in your conversation with them, that Chevy has a good 4X4, as well as Dodge.

Just a little side note...I have a fleet of 4X4's at work, all three brands. My newest F450's have both needed complete transfer case replacements. Just burned up. One under warranty, one on a long road trip. Neither abused.

Good luck,
Van