Quote Originally Posted by Evolvo View Post
When I was a kid, many years ago, I had a 57' Chevy wagon with a 265. For some reason I can't recall I pulled the thermostat out and drove it around like that. It was OK in stop and go traffic but on a steady cruise at speed I remember as I watched the temp gauge rise I would throw it in neutral and coast with the engine idling. This would slow down coolant flow keeping it in the rad longer. Throw it back in gear and watch the temp drop to normal, and on and on it went till the end of the ride. Installed a new thermostat the next day. Problem solved.
That thing about the by-pass hose has me thinking. If water takes the path of least resistance wouldn't it go through the bigger radiator hose and not the smaller by-pass hose?
Who knows the answer?
Back to Thermodynamics and restrictions - and Roger, it's been at least 35 and probably closer to 40 years for my 101 and 102.

Evolvo what you experienced in that Chebbie was localized cooling. The water pump moves the cooling fluid at different rates depending on the engine rpm. 500 rpm idle will move the coolant slowly and while moving slow, it reaches all (most, anyhow) parts of the passageways. Now, you pick up that rpm to road speeds - and since gas was cheap 'way back then' and efficiency wasn't worried about, GM probably put something like a 3.50 or numerically higher differential. That along with the 24" tall 6.70x15 tires made for road rpm at 60mph in the 3000 plus rpm range. The water pump was flailing along with that inefficient engine making lot of heat. While the pump was flailing and possibly cavitating, the coolant was merrily letting the back of the engine get nice and toasty because there wasn't an orifice (restriction) forcing the water to all reaches of the engine. And, if I recall, the temp sender on those early GM builts were in the back of a head (but may be wrong - CRS kicks in occasionally). What I can liken it to was our GE heavy duty gas turbines. The oil flow was regulated to the bearings by an orifice which also determined the temperature of that bearing as well as the journal. If an orifice was left out (done many times during maintenance) you could damage that 8" diameter assembly - and that was easily determined by the wear pattern.

If nothing else, an orifice is needed to force the coolant throughout an entire engine.

Now - my brain says it's about time to shut this computer down for the day