Tire on SUV is losing air and I don’t know why

I have a tire on my SUV that loses air to the tune of 4-5 pounds per month. I’ve looked for a nail or screw in the tread but have found none. What is your take on adding some of the tire sealant to stop the leak? My busy schedule makes it difficult to take it to a place to be fixed?

— Janice

While a sealant would probably mitigate a tiny leak such as this, perhaps for a while, I wouldn’t do it. I carry a can in each vehicle for a possible badspot-for-a-flat situation, but would hesitate using it in an elective case. The fault could worsen, and even though some sealers are touted as TPMS (tire pressure monitoring system) safe, between concern for that, and a future tire replacement technician that will hate you (super messy!), it’s best to make the time for a pro repair. A sneaker leak like this may at some point be accidentally neglected, and an SUV is the worst possible vehicle, stability-wise, to have a low tire condition. Is the valve stem cap present? If not try replacing it.

I just adopted a ‘99 Chevy pickup from my dad that wasn’t being used. It runs great but I am concerned about a clacking noise from the engine right after a cold start. It lasts for about 30 seconds and is getting better now that the weather is warming up. Ideas?

— Jim P.

This sounds like a harmless case of piston slap, a condition where the piston-to-cylinder clearance is a bit wide and the piston rocks in the bore as it passes top dead center. A sometimes sloppy original fit when the engine was manufactured compounded by a short piston skirt (reduces friction/improves economy) and normal wear can lead to this noise. As the piston warms up and expands, skirt-to-wall clearance decreases, and the noise typically goes away.

What’s the best way to get a spare key made for my Denali? It supposedly has a chip key. Do I have to go to the dealer? They wanted a fortune for one. Maybe a locksmith?

— Sully M.

It sounds like you may be contending with two issues, as the Denali likely utilizes a sidewinder (laser cut) key that contains a transponder to pair up with the immobilizer system. It can be difficult to find a hardware store that cuts sidewinder keys (some do) and they may not carry the proper transponder key blank. A locksmith should be able to take care of this without any problem, as far as the key goes, and fortunately your truck or SUV should allow on-board programming (big three American brands typically do), so you can upload the key yourself to the system. Other vehicle brands typically require the use of a pro grade scan tool in order to upload a new key. A clone key may be another option, it is flashed to imitate the original keys.

I stumbled onto a convenient ebay solution sometime back when looking into replacement key choices, an online locksmith that could take my clear photograph of an existing key, cut it into an appropriate sidewinder/ transponder blank, and promptly mail it to me with self programming instructions. The gentleman’s name is Walt Townsend at Wolf Security Hardware. I was impressed with Walt’s prompt service and clear and concise self programming instructions, in addition to taking the time to tune me up on the subject. He suggests that folks with Asian/euro vehicles get perhaps 3-5 locksmith quotes for a key and look around for a heads-up independent shop to perform the key/car handshake.