The 2010 Kia Optima.

The 2010 Kia Optima. Credit: WikiMedia Commons/Dmitry Valberg

Dear Doctor: I have a 2010 Kia Optima with a five-speed manual transmission with 39,000 miles. When the car is warmed up I am not able to shift gears. When I depress the clutch pedal and try to shift gears, it just grinds and will not engage any gear. I brought it back to the dealer who said it appears to be a defective pressure plate or thrown bearing. He also said the whole clutch assembly will need to be replaced at a cost of $1,500, a repair not covered by warranty. Is this correct? -- John

Dear John: The clutch is considered a wear item and is not covered under the powertrain warranty. I have installed many clutches over the years and always put in writing that the clutch, pressure plate, and release bearing have a one-year warranty for defects (but not if the clutch is burned out). In your case, seek a second opinion. It sounds like there is problem with the clutch disc or pressure plate. If it was defective it would not have lasted four years. -- Doctor

Dear Doctor: I have a 2004 Toyota Sequoia with 170,000 miles. Every now and then the brake light appears on the instrument panel. I've had my brakes replaced and the brake fluid purged and replaced, but the light still comes on for no apparent reason. When I turn the engine off and on again, the light goes out for perhaps one, two or three weeks, then comes on again. My mechanic said there may be a bad sensor. He sees no leakage from the master cylinder or brakes. What is causing this? -- Alan

Dear Alan: I would start for testing purposes, passing the float sensor in the master cylinder to see if the light still comes on. This can be done by unplugging the wire connector at the master cylinder. You can just unplug it, or use a connector to compete the circuit. -- Doctor

Dear Doctor: I have a 1992 Toyota pickup with 67,000 miles. The speedometer stopped working, yet the odometer was running but it, too, just recently stopped working. What is wrong? -- George

Dear George: The internal part of the speedometer has failed. Take the dash cluster out and send it out for repair or buy a used dash cluster from a salvage yard. Document the mileage difference at the time of installation if you want to show the next buyer the actual mileage. -- Doctor

Dear Doctor: I take very good care of my 2010 Honda Accord with proper maintenance (synthetic oil and all original equipment fluids and filter). I have 126,000 miles on it now, but the engine compartment has a lot of grit and dirt. How can I get the engine looking as good on the outside as it must look on the inside? Also, I own a 1978 Mercury Cougar. Would you recommend changing the transmission fluid on this car? -- Andy

Dear Andy: There are many detail shops that can clean the engine and compartment for you. I do not recommend you do it yourself. The detail shop will use a high-pressure washer and good chemical cleaner to clean the engine top and bottom, as well as the engine compartment. Regarding the 1978 Cougar, when you have the shop remove the transmission pan and filter, you are changing about half the total amount of fluid. Make sure you use the correct fluid type. I have no problem with you changing the fluid and filter. -- Doctor

Dear Doctor: I bought my 2003 Chevy Astro AWD seven years ago and from day one it shuddered on turns, which I thought was normal, and this has remained constant ever since. Yesterday a guy at the lumber yard let me drive his AWD Astro around the parking lot and it had no shudder. Why? -- Michael

Dear Michael: A shudder when turning, especially at slow speeds and tight turns, is usually caused from the center transfer case in AWD vehicles and/or the rear differential posi-traction unit not allowing the proper slippage needed. When turning the steering wheel the outside tire wants to rotate more than the inside tire. On an AWD system, all four wheels get power. On a manual engaging 4WD system, the driver has to engage the system. You will find on a manual 4WD system when turning the steering wheel (especially tight turns going slow on dry pavement) that the vehicle will actually seem like there is a problem and the steering wheel will want to move back and forth an inch or so. There are fluid friction modifiers that will help eliminate the shudder feeling. There is new technology with newer all-wheel drive systems that also ease tire wear, as well as that shudder you describe, basically by building slippage in the all-wheel drive system. -- Doctor

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