I was on highway 97C between Kelowna and Merritt a couple weeks ago. It was my introduction to the new 120 kilometre per hour speed limit in British Columbia. Portions of that road are seriously steep and the day was seriously hot. As I felt the airflow from my minivan’s ducts start to climb in temperature I was still below that 120kmh target. Yes, my fully loaded Honda was close to maxed out and still under the speed limit.
This got me thinking. Maybe a group of mechanics demanded the bump in speed limit on this road and the Coquihalla. Trying to climb a steep grade at high temperatures and at high speed is the ultimate torture test for your automobile. Some mechanics and towing companies would say it’s good for business.
You know when you are on a steady climb and your air conditioning ceases to cool that the accelerator pedal is probably millimetres from or on the floor.
You are commanding your four wheeled steed to summon all its ponies (horsepower). Running that air conditioner is using precious ponies as well as heating up the air flowing through the radiator. The engineers in their infinite wisdom feel that if you want to go as hard as you can it won’t hurt to warm you up a little.
Maybe once you get warm enough you will smarten up and let off the accelerator pedal a little. It is not only the driver and occupants that are getting warm. Think about your poor automobile.
High altitude, a steep grade, high temperatures and a full load may exceed your automobile’s cooling system capacity. Just because you can get close to or do the speed limit in these conditions does not mean you should.
It is in these conditions that a real full set of gauges would tell the real story.
I talked about gauges in a previous article and pointed out that many gauges are now no more than switches that show normal in almost all circumstances and when they are showing abnormal you have a real problem and it may be too late to recover.
It would be great to have precise readings of all lubricating and cooling fluids. In general all your fluids should be operating at roughly 100 degrees Celsius when fully warmed up. This is the ideal temperature that the engineer was shooting for in all driving situations. Now with each particular fluid there is some leeway. The engineer was under cost constraints as well as weight constraints when he concocted your vehicle’s various cooling systems.
As your vehicle ages, especially when lacking maintenance, the cooling capacity of these various systems is reduced.
A few thousand bugs in front of the radiator, maybe a little mud jammed up in the engine compartment, top it off with a few hundred extra pounds past full load and now watch your gauges closely.
That 120kmh climb will exceed your vehicles cooling capacity. If you do make it to the top don’t stop as your vehicle will cool quicker coasting down the other side.
The other option is to just back off the throttle, choose another gear, relax and enjoy the climb. Getting to the top a little slower under your own power is much easier on your car and your wallet.
Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. E-mail: nutechauto@telus.net
