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Cooling System Service
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Cooling System Service

  Engine overheating tops our informal, non-scientific poll of concerns that keep ETC member cars close to home.  Whether your Pontiac simply registers a high temperature on the gauge under certain driving conditions, or if it actually “boils over” and leaves you stranded by the side of the road, this article should cool off both car and driver.  Unless your ETC era Pontiac is completely out-fitted with the taxi or police special equipment, it was never intended for “parade” use and will certainly register higher temperature in stop and go traffic, even it does not lose any coolant.  So our first issue is to determine how hot is too hot.

Maximum Safe Operating Temperature

  The maximum safe engine operating temperature is more dependent upon the type of anti-freeze and engine oil used, than the basic materials and construction of the engine.  Even as late as 1954, alcohol anti-freeze was still in common use; but alcohol has a boiling point lower than plain water and could not be used during summer months.  It also required lower thermostat operating temperature, a 151 degrees was standard, to prevent the alcohol from literally boiling off during normal driving.  I sincerely doubt any of us are still using alcohol anti-freeze today.
  Ethylene glycol (Prestone) was available in the mid-twenties, but it was more expensive than alcohol and also had a couple of unfortunate tendencies.  The first of these is that it is much more likely to leak through hose couplings and gaskets than an alcohol mixture.  The second issue is that it is more likely to loosen rust and scale in the cooling system and could lead to restricting the flow of coolant through out the entire system.
 Another unfortunate circumstance surrounding ethylene glycol was the way it was often marketed; since it had a much higher boiling point, it could be left in the cooling system year around, hence the term “permanent” anti-freeze.  Unfortunately, because of its higher cost, early motorists would have it installed and never change it again, mistakenly believing it was “permanent”.  I recall older customers coming into my father’s service station to have their car winterized and readily accepting any ethylene glycol anti-freeze except Prestone because they had, or knew someone who had, a bad experience due to “Prestone” that was never changed and rusted out the cooling system!
  I believe it is safe to assume that all of us who use anti-freeze in our car use ethylene glycol in a 50-50 mixture.  This solution raises the boiling point above that of plain water; none of us has to worry about “boiling-over” when running as high as 220 degrees.  If you also run a pressurized radiator cap, which the majority of our Pontiacs’ featured as standard equipment, the boiling point is even higher.  A high temperature reading on the gauge deserves to be watched closely; but if there are no other symptoms of overheating, and if it appears you will soon be moving again at even low speed, you are better off continuing to drive with the expectation the temperature will drop back to normal readings with normal driving.  If you come upon an unavoidable situation in completely stopped traffic, you may have no option but to pull over and shut off the engine until the flow of traffic resumes again.  This would not have been considered “abnormal” even in the fifties; and it does not represent a failure on the part of your vintage Pontiac.  Our Chieftain is good for about 90 minutes in seriously heavy stop and go traffic; the temperature gauge running dead on HOT for the final 15 minutes without any boil-over.  I leaned this by unfortunate experience, but you could certainly idle your car around your own neighborhood on a hot summer day and learn how much is too much without being stranded far from home.
   Older engine oils were also far less tolerant of high temperatures than they are today.  Even into the early seventies, there were oils on the market that would literally solidify in the crankcase at highway speeds during summer months.  If you are using modern conventional motor oil in your Pontiac engine; 220 degree coolant temperature is not going to cause you any trouble.  If you are using non-detergent oil, API classification SB, you are probably OK at high temperature, but I would inspect the oil on the dipstick as soon as the engine cooled.  I do not recommend non-detergent API - SA oil under any circumstances; it is not required to have any helpful additives.

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