Thread: No thermostat?.....

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Originally Posted by rspears

Dave,
That is some very good tech info on the Stewart site, especially their explanation of the system being a closed loop, and slowing down the flow. This is a learning day - thanks.

I had forgotten how good their site is for this kind of information until this thread appeared - then something "kicked in". Thermodynamics 101 and 102

Originally Posted by IC2

I had forgotten how good their site is for this kind of information until this thread appeared - then something "kicked in". Thermodynamics 101 and 102

Yeah, it's been about 35 years since Thermo for me I try not to get caught up in the paralysis by analysis process...

Originally Posted by sunsetdart

I would like to make a comment on what they call dwell time in a radiator.
It does not make any difference at all if coolant flows thru a radiator at 1mph or 10mph, if it is flowing it is being cooled. The only thing happening in a radiator if the coolant stays there too long is it is building more pressure, not helping in cooling at all.

Allow me a moment to retort.... Circulation speed matters bigtime.

Here's an excerpt from an article on it.... The full article is at
http://www.familycar.com/classroom/coolingsystem.htm



Thermostat
The thermostat is simply a valve that measures the temperature of the coolant and, if it is hot enough, opens to allow the coolant to flow through the radiator. If the coolant is not hot enough, the flow to the radiator is blocked and fluid is directed to a bypass system that allows the coolant to return directly back to the engine. The bypass system allows the coolant to keep moving through the engine to balance the temperature and avoid hot spots. Because flow to the radiator is blocked, the engine will reach operating temperature sooner and, on a cold day, will allow the heater to begin supplying hot air to the interior more quickly.

Since the 1970s, thermostats have been calibrated to keep the temperature of the coolant above 192 to 195 degrees. Prior to that, 180 degree thermostats were the norm. It was found that if the engine is allowed to run at these hotter temperatures, emissions are reduced, moisture condensation inside the engine is quickly burned off extending engine life, and combustion is more complete which improves fuel economy.

The heart of a thermostat is a sealed copper cup that contains wax and a metal pellet. As the thermostat heats up, the hot wax expands, pushing a piston against spring pressure to open the valve and allow coolant to circulate.

The thermostat is usually located in the front, top part of the engine in a water outlet housing that also serves as the connection point for the upper radiator hose. The thermostat housing attaches to the engine, usually with two bolts and a gasket to seal it against leaks. The gasket is usually made of a heavy paper or a rubber O ring is used. In some applications, there is no gasket or rubber seal. Instead, a thin bead of special silicone sealer is squeezed from a tube to form a seal.

There is a mistaken belief by some people that if they remove the thermostat, they will be able to solve hard to find overheating problems. This couldn't be further from the truth. Removing the thermostat will allow uncontrolled circulation of the coolant throughout the system. It is possible for the coolant to move so fast, that it will not be properly cooled as it races through the radiator, so the engine can run even hotter than before under certain conditions. Other times, the engine will never reach its operating temperature. On computer controlled vehicles, the computer monitors engine temperatures and regulates fuel usage based on that temperature. If the engine never reaches operating temperatures, fuel economy and performance will suffer considerably.

Originally Posted by Evolvo

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

Originally Posted by IC2

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).

Oil pressure in the back of the block, water temp in the front of the manifold, on the passenger side if I'm not mistaken and no provision in the heads for water temp.

WOW! What great info! Thanks all..... I've decided to try another new t-stat (boiled first to check) and go from there.....if that does not do it......

David

Something else to pass on..........most all sending units for the temp gauge is located on the front of the manifold , near the upper hose outlet to the radiator. So since the coolant is passing this sender, one has to remember that the coolant will be at it's hottest . The gauge may read say 200-220 or even hotter, but the coolant is also leaving the motor and going into the rad for cooling. You are not temping coolant in the block , it is coolant temps of the what's leaving the motor. If the fan, rad, pump are doing their job, coolant temps coming back in the suction side should be 15-20 deg cooler.

ok.....pulled the tstat - glad I did as I absent mindingly put a 160 in there and not a 180. Anyway - boiled it and it opened right on time. So, now my quandry - even at 160 it seems that there was no flow.

Only 2 things I can think of: 1) can there be an 'airlock' in the system - or is that not possible given the bypass? or 2) the temp sending units are sending a wrong signal to the gauge and I am really ok.

Off to the parts store for new 180 degree high flow and will drill holes in it as well - two 3/16" in the bottom.....

OK..... We have SUCCESS! Got a new 180 tstat, drilled 2 3/16" holes and put them on the bottom when I installed the tstat. Immediatey, I could feel the radiator getting a little heat until finally - the new electric fan kicked on (YES!).

Pending weather tomorrow, will be able to back it out of the garage and drive it for the first time in a couple years. Now it's time to dial in timing and the carb.

I can't remember who said it, but looks like I'm going to have to ditch the oil breathers (DANG IT, I love how they look), but I can see the smoke coming out of them.

So happy.......

Thanks to all for the info and ideas.

David