Solving a spark plug problem

Q: In a recent column you responded to R.W. from Minnetonka, Minnesota, that he should not need spark plug replacement of the platinum tipped plugs until the manufacturer recommended 60,000 miles. One thing that is often not considered is that over time, the dissimilar metals in the aluminum heads and the spark plug materials make removal of the plugs difficult and potentially costly. Manufacturers tell vehicle owners that items have a longer service life than they actually do. — J. K., Deerfield, Illinois

A: Although they are dissimilar metals, the steel spark plug shells seldom seize with the aluminum cylinder heads. Mechanics used to apply anti-seize compound to the spark plug threads (some still do), but most plugs are treated and no longer require the stuff. One notorious problem, however, was the Ford Navistar engine whose spark plugs extended extra far into the combustion chambers. A buildup of carbon made them nearly impossible to remove without damage. That is a case where the problem was avoided by replacing the plugs more often.

Q: I enjoy your column and now need to ask if something my husband does is creating a repeating problem. He had a Dodge Durango 2003-10. He ended up selling it because the heat stopped working. He purchased a new Chevy Tahoe from 2010-18 (over 250,000 miles). He ended up selling it because the heating and cooling stopped working. He purchased a used Chevy Colorado with 30,000 miles two years ago. Now the heating is intermittent at best. Now he is considering selling it because of this problem. The common denominator seems to be he keeps his defrost on. Would this have anything to do with his last three trucks all having the same issues? — B.D., Chicago

A: Even if defrost is chosen, heat should be adequate. Although the air conditioner runs whenever defrost is selected, it would be quite unusual for the heat to fail just because of that. The A/C draws moisture from the air thus keeping the windshield clear. Perhaps the blend door, that mixes the hot air with the cold air, may be malfunctioning. But the chances of this happening three times in a row are questionable.

Q: I have a 2010 Mitsubishi Galant SE with 120,000 miles. Recently the “service engine soon” light has come on. My guy ran a diagnostic and came up with my needing to replace the evap vent solenoid Mitsubishi part #8657A008. Problem is Mitsubishi no longer makes this part. Googling for the part name brings up a totally different part number that does not fit my car. The local Mitsubishi dealer tells me there are none of the correct part available anywhere and there is no alternative or workaround — but I should feel free to come in and trade for a new car. There are tons of these units still on the road!

P.T., Forest Lake, Illinois

A: Auto dealers are generally required to have parts available for only seven years. Of course, some may have the part, but tracking it down is a hassle. When the original part becomes unavailable, I turn to the aftermarket parts companies. One such

company, Dorman, sells the purge valve you need. Check with your local auto parts store. We called an Advance Auto store, and they showed 200 available upon special order.

DREAMSTIME Mechanics used to apply anti-seize compound to the spark plug threads (some still do), but most plugs are treated and no longer require the stuff.