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

Phil Coconis
by Phil Coconis
memoirs of an independent repair shop owner em cold weather cause and effect not

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.

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3 of 14 comments
  • Hoser Hoser on Mar 03, 2013

    My Chevette pulled that trick on me across the state of Illinois once. The vacuum switch that triggered the warm airflow over the exhaust manifold failed. The resulting temps had me pulling over at every rest area and using the hand dryers in the bathroom to thaw my air filter. The warmth of the engine thawed the carb and I'd head out again, only to be 35-45mph top speed by the next rest area. I was on the road and focused on getting home. Knowing what happened now, it would have been a simple procedure to reroute the vacuum lines bypassing that switch and making it home with no drama.

    • Redmondjp Redmondjp on Mar 04, 2013

      Yes, in cold weather, there would be no problem with routing full manifold vacuum to the dashpot on the air cleaner intake snorkel such that fully heated intake air via the exhaust manifold would have been used. I knew one or two people who used to connect theirs in exactly that manner, for winter months, and then just disconnect it in the summertime.

  • Phargophil Phargophil on Mar 04, 2013

    I solved this on my '81 Eagle daily driver by installing a manual choke cable. SOOOO much more reliable!

  • Svenmeier Speedometer display in the center console screen? Why? This is a dealbreaker for me.
  • Alan I do believe that traffic infringements penalties based on income will affect those who are financial able to flout safety regulations.When I drive above the posted speed limit I assess my situation using probability. If I'm confronted with a situation where time is of more value to me than speed I will speed if I assess the probability of a fine to be quite low. I can afford the fine, what I can't afford is the loss of points on my drivers licence.In Australia (12 points in QLD and all States have a point system) we have a points system attached to your drivers licence. An open drivers licence is granted 12 points every 3 years. So, if you receive an infringement for exceeding the speed limit it takes 3 years for the points to be removed. I generally get caught once every 2 years.I think a points system would be a fairer system over a system based on income. Its about retaining your licence and safety, not financial gain by the government.As you can see below it wouldn't take long for many US drivers to lose their drivers licence.[h2]Current penalties for individuals caught speeding[/h2]InfringementPenalty amountDemerit pointsLess than 11km/h over the speed limit$287. 1 pointAt least 11km/h but not more than 20km/h over the speed limit$431. 3 pointsMore than 20km/h but not more than 30km/h over the speed limit$646. 4 pointsMore than 30km/h but not more than 40km/h over the speed limit$1,078. 6 pointsMore than 40km/h over the speed limit$1,653. 8 points and 6 month suspension
  • Wjtinfwb Instead of raising fines, why don't the authorities enforce the laws and write tickets, and have judges enforce the penalty or sentence of a crime. I live across the street from an Elementary School on a 4-lane divided state highway. every morning the cop sits in his car and when someone sails through the School Zone well above the 10 mph limit, he merely hits his siren to get their attention but that's it. I've never, in 5 years, seen them get out of the car and actually stop and driver and confront them about speeding. As a result, no one pays attention and when the School Zone light is not lit, traffic flies by at 50-60 mph in the 45 zone. Almost no enforcement occurs until the inevitable crash, last year some zoned out girl rolled her beater Elantra 3 times. On a dry, straight, 4 lane road with a 45 mph limit. I'm no Angel and have a heavy foot myself. I've received my share of speeding tickets, lots of them when younger. Traffic enforcement in most locales has become a joke these days, jacking prices because someone has a higher income in as asinine as our stupid tax policy and non-existent immigration enforcement.
  • Jeff S If AM went away I would listen to FM but since it is insignificant in the cost to the car and in an emergency broadcast it is good to have. I agree with some of the others its another way to collect money with a subscription. AM is most likely to go away in the future but I will use AM as long as its around.
  • BEPLA I think it's cool the way it is.If I had the money, time and space - I'd buy it, clean it up, and just do enough to get it running properly.Then take it to Cars and Coffee and park it next to all the newer Mustangs.