4 Wheel Drive/SUVs: Mercury Mountaineer AWD, wheel drive vehicles, mercury mountaineer

Question
Approx 96,000 miles on a 2002 Mercury Mountaineer and problem has started that sounds like a 4-wheel drive problem.  Taking off from a stop, turning the steering wheel, I get a sound that is much like the "shudder" that comes with taking off in gravel with 4-wheel drive engaged in my Nisson that has manual 4 wheel drive.

Dealer says they think that problem will be solved by my replacing 4 rather new Michelin tires because of uneven wear (perhaps 1/8th inch on one tire) causing AWD sensor to think one wheel isn't turning as fast as the others and kicking 4WD into action.

The tires I replaced were really worn unevenly and problem should have showed up with them as well, but it didn't.  The problem occurs after driving for a couple hundred miles and not when leaving the garage.

Any ideas to explore?
Thanks
Dale

Answer
Dale,

First,double check the tire pressure.  It is very important on any 4WD vehicle that the tires have equal pressure so that one tire isn't turning a different rpm than the others.  Also rotate the tires.  This should determine if the front tires were causing the problem.  Your dealer should have thought of this.

Next, you need to get the front end aligned due to the uneven wear of the tires.  Make sure that you take it to a reputable front end shop, preferably one that specializes in 4-wheel drive vehicles.  

If this doesn't correct the problem, then you may have a sensor that is going bad when it heats up.  This can occur after driving for several miles.  Another possibility, is that you have a front wheel or axle bearing going bad.

Carl