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4 Wheel Drive/SUVs/Mercury Mountaineer AWD

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Expert: - 1/10/2006


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

4 Wheel Drive/SUVs

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Carl Brandt

Expertise

Will discuss suspensions, lifts, lockers along with tire suggestions. Trail ratings and possible requirements needed for specific type of trails. Safety equipment and what you should carry with you. Certified off-road instructor. I am not a mechanic, and 4-Wheeling is a hobby, so if I can't answer a technical question it is due to my mechanical knowledge being related to vehicles that I have owned, or have worked on. I do not have manuals on all vehicles.

Experience

40 plus years of 4 wheeling in a variety of vehicles. At the present time, my major off-road rig is a 94 Jeep Wrangler with a spring over and a 1 1/2" suspension lift. This gives me a total lift of 7" or so. I have lockers front and rear. I have removed the track bars, and sway bar for maximum articulation. I am running a stock 2.5 ltr 4 cylinder with a Jacobs ignition along with a cold air high flow filter. It has 4.56:1 gears with a Dodge NV4500 transmission along with a 3.8:1 Atlas II transfer case. This gives me a final ratio of 105:1 in low gear/low range. Other vehicles I own, are a 96 Ford F-250 with a 6" lift, posi rear end, 36" Hummer tires, 5 speed with a fuel injected 460 ci engine, an 87 Samurai with an 8" lift, Ford 9" rear end with a spool, Chevy Dana 44 front end with an electric locker, 5.88 gears, 16% reduction in high range and a 6.5:1 low range with 35" Baja Claws, and a stock 2003 Grand Cherokee Overland. Trails I have run are the Rubicon (10 times), Dusey Ershim, Fordyce Creek trail, McGrew trail, several trails in Moab, Utah along with local monthly runs.

Organizations
Lost Coast 4x4's Cal 4-Wheel Corva UFWDA Blue Ribbon Coalition

Education/Credentials
Certified off-road instructor - Certificates in engineering/electronics

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