Q My daughter has a 1999 Volkswagen Jetta with a 2.0-liter engine and 108,000 miles. When I remove the oil filler cap, I notice moisture buildup inside the engine -- a white sludge around the fill cap area. I can usually wipe out most of the moisture with a clean rag. I have been changing the oil on a more regular basis every 2,000 to 3,000 miles in an attempt to reduce the moisture. In the summer, the buildup is less noticeable than in winter. The coolant maintains the proper level, and oil consumption is about two-thirds of a quart per 2,500 miles. Any thoughts on what might be causing the moisture buildup?A The low mileage would seem to indicate infrequent use or short trips -- both of which can promote condensation inside an engine. Other potential causes are low engine operating temperature, a blocked PCV (positive crankcase ventilation) system or a failed temperature regulator thermal vacuum valve, which is designed to preheat incoming induction air.

As the engine warms up, moisture in the air inside the crankcase condenses into liquid form on the cold internal engine parts and is carried throughout the engine by the motor oil. If the engine does not or is not allowed to reach and maintain full operating temperature for a reasonable period of time, it never evaporates, and it turns into a whitish goop on the oil fill cap, dipstick and inside of the valve cover.

Changing oil more frequently helps remove this buildup, but the best answer is to make sure the thermostat is bringing the coolant up to full operating temperature and driving it at that temperature for at least 30 minutes every few days.

Q I have a 2008 Ford Fusion. Last year and this year I drove the car to Colorado for a ski vacation. Elevation at the resort is about 8,000 feet. Each year I noticed that every day when I start the car there seemed to be about a two-minute delay before the power brakes worked. After the car idled for several minutes, the problem would disappear. I checked the fluid in the master cylinder, and that is not the problem. The car has no other problems, and the brake pads have plenty of life left on them. Any idea what causes this?

A The most likely scenario is moisture freezing in the vacuum system for the power brake booster. Until this moisture thaws, no engine vacuum reaches the booster, leaving you with that rock-hard pedal. Once the moisture thaws, the problem disappears. The component most likely to freeze up is the vacuum booster check valve. Cleaning or replacing it before your next winter trip might prevent this.

Q I have a 1996 Ford F-150 pickup with about 85,000 miles on it. The past few years it has been sitting in the driveway because of some physical problems I have had. One day, the horn gave a few short blasts. A few hours later, it was a long, continuous, annoying honk. We looked outside and found it was my truck -- just honking away for no reason. We called for help, and they pulled the wires on the horns under the hood.

The next day, we saw that the warning lights in the truck were flashing. We disconnected the negative battery cable and have not had any problems since. Now that spring is here, I would like to get the truck in running condition again, but I'm afraid that if I just hook the battery back up, it will once again start with these intermittent "hauntings."

A I think a family of rodents has moved in and homesteaded your truck. These little critters seem to love rubber and chew up wiring insulation. The random electrical issues point toward individual wires in harnesses shorting together. Take a close look at the harnesses under the hood and dash.