Q: One of your recent columns reinvigorated the discussions I had in the past about the timing setup for my 2005 Toyota Scion xB. It had a timing chain (like the triple primary drive chain on my Harley with metal links). Is there any difference in wear and tear and longevity between a rubber timing belt and a metal timing chain?

A: The primary drive chain on your Harley is quite similar to the Scion timing chain. And the final drive belt on your bike is similar to a timing belt of rubber reinforced with tensile cords. Unlike rubber belts, there is no schedule for replacing the chain.

Pressure-packed question

Q: I read your article about tire pressure dropping 1 psi for each 10 degree drop in ambient temperature. If the recommended summer tire pressure is 35 psi, what is the proper pressure in the winter? Should you always set it to 35 psi regardless of the ambient temperature?

A: Your question is like those that I've gotten from many readers. Short answer: No matter the ambient temperature, inflate your tires to the pressure on the door sticker.

Hidden solution

Q: This is in reference to your advice regarding a 2008 Toyota Solara tire pressure warning light. It reminded me of a similar situation l had with my mother's 2011 Toyota Avalon. It turned out that Toyota had fitted the car with a full size spare tire, which also included a sensor. I inflated the spare tire to specifications, and the problem was solved.

A: Right you are. Because full-size spare tires are almost extinct, this solution never occurred to me.

Smoke signals

Q: I have a 1983 Mercedes 380SL that on rare occasions blows a dense whitish smoke from the exhaust. The car has a little over 80,000 miles on it. It is stored during winters. This past summer there was absolutely no smoke for over 300 miles, then, suddenly, smoke.

It usually happens when first started and driven. Also, it happens after the transmission seems to hang up shifting gears. The automatic transmission fluid is full. I've had the transmission modulator changed three times using both aftermarket and Mercedes parts. Each time, the rubber in the modulator looks fine, but the problem continues. It only smokes for a couple of minutes. Any ideas as to cause and remedy?

A: My first thought is that there's a problem with the transmission vacuum modulator. There could be a tiny leak in the diaphragm allowing transmission fluid to seep into the housing. When you start the engine, it sucks the fluid in, burns it and emits smoke from the tailpipe. But there is another source for white smoke (steam): a bad head gasket. Keep an eye on your coolant level. If it drops and there are no obvious leaks, the gasket might be the culprit.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to motormouth.tribune@gmail.com.