Q. I have a question with reference to the “Drive Types Explained” portion of your Car Doctor column in the Journal. My 2003 Chevrolet S10 pickup truck has 2-wheel or 4-wheel drive controlled by a push button on the dashboard. When I am in 4-wheel drive, there is no slip between the two front wheels. This makes for some bucking when turning the car, forcing me to switch out of 4-wheel drive for anything other than basically straight ahead driving. Shouldn’t there be some limited slip? I assume that AWD cars have some sort of limited- slip front differential.

A. Traditional four-wheel drive systems like yours are designed to be driven in four-wheel drive when traction conditions are poor such as snow and mud. When the roads are dry there will always be some amount of binding when taking a turn. Although in the case of your vehicle it sounds like it is a bit more severe. The first place to start is with computer diagnostic test and then look at the condition of the drive line fluids.

Fix your wagon

Q. My 1996 Volvo wagon with a manual transmission has 150,000 miles on it. I had the dealer run the diagnostic, which indicated a vacuum leak at the intake manifold. This repair will cost $700. I am told the car will not pass inspection if this is not repaired and there is a risk of damage to the catalytic converter as well. The car is running OK, although occasionally I feel some kind of skipping. Does any of this sound reasonable? I’d love to keep this car for a few more years.

A. It is possible the intake manifold has a vacuum leak, but don’t rule out something as simple and inexpensive as a leaking vacuum hose. A vacuum leak will cause the engine to run “lean” and more than likely will not pass the emissions test. If the engine does start to misfire, the catalytic converter could become damaged. My recommendation is to repair the car, maintain it and enjoy for many more years.

Dangerous bearing

Q. I own a 2001 GMC four-wheel-drive Jimmy. For the past several weeks I have hearing a scraping/squealing sound off and on from the front right wheel. I first started hearing it on left turns or while bearing left at a low speed. Then it would sound off and on while driving everywhere, even on the highway. Any ideas what might be happening? It is getting louder too.

A. It is possible your Jimmy has a faulty wheel bearing. You should get it to the repair shop as soon as possible. If the bearing fails while driving it could be catastrophic.

Don’t blame inspectors

Q. Recently I had my Lincoln Town Car into a repair shop for a state inspection. When driving the car about two weeks later, as I was coming to a stop, the lower ball joint broke. The repair shop that replaced the ball joint said it was rusted. I went back to the inspection station since I feel they should be responsible for the repair. What do you think?

A. The ball joints in some Town Car and Crown Victoria models will seize up when they wear, unlike other cars in which the ball joints become loose. It is very easy to overlook this since the inspector is looking for movement, not for the part to be tight. In this particular case, I don’t believe the inspection shop should be held responsible.

projocars@projo.com