Yukon's sealed ball joints are nothing to worry about

Q The ball joints on my 2007 GMC Yukon were diagnosed by an independent shop as needing replacement. The truck has 55,000 miles and is under warranty. When I took it to the dealer, they shook the wheels and told me there was nothing wrong with the ball joints. It is my understanding that the '07 models had ball joints without Zerk fittings to allow lubricating with a grease gun.

My concern is the greaseless joints are prematurely failing and I'm getting the runaround from the dealer on the warranty claim. The "shaking" or "rocking" of the wheel seems very subjective in evaluating ball joints. Are there alternative wear indicators for determining replacement?

A Pulling or pushing up and down on the suspension is the correct initial test for worn ball joints. If play is seen or felt with this simple test, GM then suggests measuring the play in the upper and/or lower ball joint with a dial indicator. If measurable play is more than 2 millimeters (0.08 inch), the ball joint needs replacement.

By the way, there's no inherent problem with "greaseless" suspension components -- they are lubricated and sealed when manufactured and require no periodic maintenance.

Q My 2002 Windstar's "ABS" and "Brake" lights come on intermittently. Our service man has replaced the pads and turned the drums. This works for a while, but then both lights come on again. I've been told that the brakes are fine but the antilock brake system (ABS) is probably not working when the light comes on. What is going on here?

A If the brake warning light comes on, there is the potential for a serious hydraulic brake problem that could affect the safety of the vehicle. The brakes are not working fine. Yes, when the brake warning light illuminates, the ABS will also be disabled and the ABS warning light will come on.

The brake warning light will light up for one of three primary reasons: low brake fluid level in the master cylinder, hydraulic pressure loss or significant difference in one-half of the diagonal hydraulic brake system, or the parking brake mechanism sticking on.

Also, does your vehicle have an "LTW" (low tire warning) light on the dash? If so, the vehicle has a tire pressure monitoring system that uses the differences in wheel rotational speeds while driving to identify a tire with significantly low pressure. Low tire pressure will reduce the rolling diameter of the tire, which the wheel speed sensor will read and communicate to the ABS module. Make sure this isn't a factor in the ABS warning light coming on.

Q We recently purchased a 2009 Ford Escape with about 37,000 miles on it. Last weekend I was washing and waxing the car and I noticed a bit of rust and paint bubbling along the bottom inside edge of the tailgate. We didn't buy this car at a Ford dealership, but I was wondering if there were any bulletins about this problem and if they would fix this. If not, do I just scrape it off and apply primer or touch-up paint?

A My Alldata automotive database did not find any Ford bulletins covering paint problems on this vehicle, but you could certainly call a Ford dealer to double-check. Living where you do -- Minnesota -- corrosion and paint problems are far more likely environmental issues -- read that as road salt used during the long winter months.

And yes, you should do something to restore the rust and bubbled paint now before it gets worse. Remember, rust never sleeps!