Mercedes vehicle will tell you when to replace brakes
Q: My wife and I have a C300 Mercedes with 55,000 miles. Every time the car has been serviced, I’ll ask for a brake check even if it’s not part of the service code. They always check fine. My adviser has told me repeatedly that there will be an “idiot light” indicating time to replace but it hasn’t happened.
Occasionally, I’ll feel the front wheels pulsing (as to indicate wear or warp) but it diminishes as quickly as it appeared. I’ve never had a car that has gone this long without a replacement of some kind. Are their pads so much better? Does the “always insist on genuine parts” really mean something? — N.L., Tamarac, Fla.
A: Yes, you can always rely on the original equipment parts to be what came with the vehicle, but improved parts may be available. We like to replace the pads when the lining wears down to about 4-5 mm. Your car is equipped with wear sensors that will trigger a reminder light when it is due for brakes. That pulsation you feel is probably surface rust on the rotors that gets wiped off by the brakes after a few applications.
Q: I have a 2004 Chevy SSR whose convertible top will not retract. It has only 25,000 original miles. I brought it to the Chevy dealership to have it checked out. They informed me that the pump motor needed to be replaced, but the part was discontinued and there was nothing they could do.
So now I have a vehicle that I can’t use or sell with the top down. I have interested buyers but not if the top is inoperable. They only made the SSR for four years. Is there nowhere to find a new motor? The car is in pristine condition otherwise. — P.O., Methuen, Mass.
A: We Googled SSR convertible top motors and got numerous returns. Some were professional rebuilders some were used motors on ebay. One was a wholesale GM parts company.
Q: I have a 2017 Hyundai Santa Fe with one of those fancy heated windshields. I have never used this feature and think it’s overkill. Now I need to replace the windshield due to cracks and chips. What would normally be a $150 replacement is now $275.
Can I decline the fancy windshield and just get a regular one? Will the shop let me do this or are they legally required to replace like-for-like? Also, what do you think of those roadside windshield crack repair vendors? — C.V., Chicago
A: Most small chips such as stone damage are reliably repairable. Most insurance companies will cover them with no deductible. Yes, you can replace the windshield with a nonheated one.
Q: I have a 2011 minivan. I place a thermometer in the A/C outlet vent in the summer to observe the air temperature. Today the outside temperature was 93, and the thermometer in the A/C vent read 58. (I’m not complaining, as the A/C performance is acceptable.) Is there is a mechanic’s rule of thumb that says if/when the delta temperature with the A/C operating reaches a certain number it is time to add a can of refrigerant? — R.R., Lisle, Ill.
A: There is no rule of thumb. A tech needs to connect a set of gauges to read the high-pressure and low-pressure sides of the system to establish the need for more refrigerant. Modern vehicles seldom leak refrigerant unless something was damaged. Keep in mind that outside temperature and humidity do affect the air conditioning performance. Relax. Be cool.
Bob Weber is a writer and mechanic who became an Asecertified master automobile technician in 1976. Send questions along with name and town to motormouth.tribune@gmail.com.