MEMOIRS OF AN INDEPENDENT REPAIR SHOP OWNER: Cold-Weather Cause-And-Effect (not “Tall Winter Tales”)

As long as it's still the winter season in the Northern Hemisphere—more wintry for some than others, here in the U.S.—it seems appropriate to stay on that topic for a while longer, here on the "Memoirs" page. Having spent much of my career as an auto tech and shop owner in the Southern California area, I really didn't get much of an opportunity to solve cold-weather problems on customer vehicles—mainly because there just wasn't (and still isn't) much of that stuff going around, down there. Moving to New York—and then Louisiana—in the '80's quickly changed all of that. Of course, most vehicles had carburetors back then; and compared to those equipped with fuel injection, they tended to be more susceptible to the cold—especially when accompanied by high-humidity conditions (of which there is no shortage in either locale). This fact led to a number of personal cause-and-effect revelations, which, while unfamiliar to me, undoubtedly were familiar ones to the locals. They were interesting revelations, nonetheless; and I'm going to relate a couple of the highlights right now. When it came to choke systems on most typical carburetors of the day, I found that choke setting was not terribly critical in SoCal, as long as the plate was fully open when the engine was warm. Yes, setting did become a bit more critical on "emissions" carburetors—and British vehicles always had to have a fully functional choke (technically referred to as "cold-start enrichment"), even on the typical Los Angeles "cold" start. But drop the temperature down to anywhere at or below freezing, and any flaw—however subtle it may have been—made its presence known in no uncertain terms. Choke plate not closing enough? You might have to pump the living daylights out of the accelerator pedal just to get the engine fired and keep it running long enough to warm up, and run without stalling at idle. Choke vacuum break not operating (with a properly adjusted choke plate)? Sure, the engine would start right up, only to be shortly followed by pronounced "chugging" and massive amounts of black smoke out the tailpipe. On later "emissions" engines, the thermo-vacuum valves controlling this process would fail and cause the same sort of conditions. I personally owned a Honda Accord that experienced that problem. On GM cars of the day, even a "no-charge" alternator condition would cut power to the choke heater coil, and the choke would fail to open quickly and completely. Unlike the "repair wiggle room" prevailing atmospheric conditions in the Southwest afforded, attempting some kind of witty bypass maneuver in true winter climes got you into more of a mess than biting the bullet and just making the O.E. system function by the book. Another problem I ran across—especially during the winter in Louisiana—was a malfunctioning intake air control system wreaking havoc with vehicle driveability. The customer would claim that they'd be motoring along without a problem—often at a steady state highway cruise—and the engine would lose power, and eventually sputter and shut off! If they'd let it sit for a few minutes, they could restart without problem, and resume cruise for about five to ten minutes before experiencing the power loss and stall all over again. Now in Los Angeles, the only problem I had experienced with TAC (Thermostatic Air Control) on carbureted engines, was when the air door would stay closed off to cold air, and engine "ping" followed by "vaporlock" when returning to idle would ensue, due to excessive heat in the intake air. Yes, that problem would also occur—probably even more acutely—in the Deep South. Usually, the quick and temporary solution to that problem was to make sure that the air door stayed open to cold air only; without much concern for any consequence involving the need for hot air, at any point. The strategy worked in the City of Lost Angels, but not in the State of LA. At least not for year-round vehicle use! What would happen during the winter, if the TAC system was not providing enough heated air to the carb vis-à-vis the air filter housing, was the formation of ice around the throttle plate. If the ice buildup got heavy enough, it would literally shut off the engine! In the state of LA, it didn't have to be really cold for this to happen, either. It could get so damp down there, ambient temperature only needed to drop to around 50F for that to happen! The customer would always be surprised when they learned that this was the sole cause of the problem! Stay tuned for more "revelations", next week. Phil ran a successful independent repair shop on the West Coast for close to 20 years, working over a decade before that at both dealer and independent repair shops. He is presently semi-retired from the business of auto repair, but still keeps his hand in things as a consultant and in his personal garage. from The Truth About Cars http://www.thetruthaboutcars.com

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