UNDER THE HOOD
Behind the popularity of 2.0-liter engines
Q:
I was curious why there seems to be such a huge number of 2.0-liter engines on the market now. What is there about this size that makes it so popular?
—Frank H.
A: What we're seeing, thanks to the benefits of direct fuel injection, variable valve operation, and turbocharging are four-cylinder engines with plenty of power for the average car. Light weight and easy packaging are bonuses as well. Why 2.0 liters of displacement? A while back European scientist/engineers determined that 500cc (0.5-liter) cylinders were the ideal size for internal combustion engines. Keeping an engine's internal surface to volume ratio as low as possible is also desired as less combustion heat is transferred to the cylinder head, and hydrocarbon emissions are minimized. This means many engines now have a bit longer stroke and smaller bores than before. Looking around at various engines, particularly BMW, Mercedes, and VW shows the 0.5-liter concept; 1.5liter three cylinder, 2.0-liter four cylinder, 3.0-liter six cylinder, 4.0liter eight-cylinder, and 6.0-liter twelve cylinder engines.
Q: I’ve got this one tire that loses about 3 pounds of air each month. It drives me nuts to have to keep checking and refilling it. At the last oil change I had them check it for leaks and they couldn’t find one. I’ve probably got another year maybe two left on it. Sealer? Live with it?
—Val B.
A: Most tires lose about a pound a month, with a lot of variables. Possible leakage points are the tire valve-stem connection at the wheel, the core (valve) inside, the tire-wheel bead seal, and a puncture, likely in the tread area. I'm wondering if your service place used a tire leak testing tub or simply sprayed water on it. Your leak is small but should show up with a diligent inspection. An application of tire sealer would likely do the trick except that it might make trouble with your TPMS sensor inside and it makes such a mess you'd need to bring a box of doughnuts and a big smile to the next person who'll need to service or replace the tire.
How about mixing up a dash of dishwashing liquid and water in a spray bottle and double checking at least the accessible parts of the tire yourself? Don't forget also to remove the valve stem cap and gently snug the valve core, using the appropriate tool. You might try using a brush to work the soapy solution a little more into the tire bead and tread areas. With patience and repositioning the tire on the ground, there's a good chance the leak will show up.
If it turns out the leak is at the bead, there's a chance the tire was nicked slightly during installation, the wheel bead wasn't adequately cleaned, or the wheel's surface plating is flaking or eroding. A bead sealer product can be applied to the surfaces to help with minor flaws.