What caused a one-time brake pedal issue in my SUV?

John Paul, AAA Northeast's Car Doctor, answers a question from a reader with a brake pedal issue.

Q. I have a 2011 Lincoln MKX with 126,000 miles. Back in July, I had a one-time occurrence where my brake pedal went to the floor, with braking capability very much diminished. There was no issue with the brake fluid and my mechanic could not come up with a physical reason that caused this. This happened again last week, and the mechanic did a deeper dive and still couldn’t give me a reason. He said he had this same problem once before with a Ford Explorer. After changing that SUV’s master-cylinder and one other part (which I don’t remember), he told me he would not give his customer a guarantee that it would not happen again. Are you aware of anything about this or has Ford/Lincoln issued any bulletins about this problem? Also, with proper maintenance (I drive about 10,000 miles per year), what life expectancy can I expect from this vehicle?

A. The brake master-cylinder is the typical cause of a dropping or fading brake pedal. The system will typically present itself while waiting at a stop light with your foot lightly resting on the brake pedal. So as a pure guess, it is a pretty good one. I found no technical service bulletins that addressed this specific problem. Regarding how long this car can last depends on how it is driven and maintained. With normal care it should be able to reach 200,000 miles with ease. Now of course there could be some expenses on the way. The transmissions in some of these models can be problematic. Also, as the car continues to age, it would not be unusual to have issues with the climate control system, power windows/locks, and even the infotainment system. Keep in mind that it is almost always cheaper to fix an old car than buy a new one.

Q. I am very diligent regarding oil changes, but I have a frequency question. I am the original owner of a 2005 Mercedes CLK 320, and the car presently has just under 70,000 miles. The car is used about five months a year, and probably gets driven around 2,500 miles per year. I have been getting annual oil changes to date. My question is as follows; considering that the V6 engine requires eight quarts of synthetic oil, and considering that the car sits unused between mid-October and mid-May, would two years between charges make sense?

A. Mercedes has one of the most sophisticated oil monitoring systems of most any manufacturer. Mercedes does state that yearly service is recommended. We have a VW Beetle convertible that sits for six months, and I still service the engine each year. Could you go two years between oil changes? Probably. Would I? No.

Q. Do you have any suggestions for how to prevent mice from eating the wires of your car? My understanding is that many newer cars have soy-based wiring that mice love. Is there anything you can put inside the car to keep them out?

A. Soy is used in wiring and foam, but it is not a food product. Old wiring was petroleum based which may have been somewhat of a deterrent. That being said, I have repaired many old cars whose wires were eaten by rodents. Some things you can try, Shake-A-Way (there are others), which is supposed to give off a predator scent. Peppermint oil in tea bag-like packets is supposed to work. Other people have told me they leave Irish Spring soap shavings in the car. If parked in a garage, block any entry holes and remove any food. If parked outside, try to stay away from trash cans. There is also a heavy car cover from Cover Seal. This is a heavy weighted cover that can keep out rodents.

Q. I purchased a new 2024 Subaru Crosstrek with cloth fabric seat covers. After about two months and 500 miles we now see premature wearing (fuzzing) of the driver’s seat bolster area. I did some online research and discovered this problem of wear going back as far as 2014. A TSB was even issued by Subaru stating that the original fabric was defective, and a better-quality fabric was available for replacement. I brought the car to the dealer, and they ordered a replacement “part” which is covered under warranty. It is still on backorder. I see online that this continues to be a problem with Crosstreks. My question is what about the rest of the fabric in my car’s interior? One writer on a recent forum said his seat fabric has been replaced three times. Have you heard anything about this issue and has Subaru finally solved the premature aging defect? What is my recourse if this continues when the car is out of warranty? My wife and I are both retired and never wear any type of rough clothing that would cause fabric damage.

A. I have seen no technical service bulletins listed for 2023/24 Subaru seat wear. I did find a Reddit posting about premature cloth seat wear that spans several years. At this point all you can do is work with Subaru of America and have them replace the seat. I did locate the TSB from 2014 and over the past 10 years, the seat material and even the supplier could have changed several times. It has been my experience that once the situation with a defective product is resolved with an improved product, there will be no extension of the warranty. Once the warranty time and mileage are met, then that is the manufacturers’ only obligation. Now if the replacement product is the same as the original product, I have seen manufacturers step up and replace items outside of the warranty period. It also helps if the dealer is on your side to pursue the issue with the manufacturer. I recently road tested the 2024 Crosstrek with cloth seats. The car has been driven by many journalists and had about 9,000 miles on it and showed no signs of seat wear. Based on that perhaps the issue has been resolved. 

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your Car Doctor question to [email protected]. Listen to the Car Doctor podcast at johnfpaul.podbean.com.