Which Tstat ?

[cschulzy]

Which is the best tstat to use. I want to get a hypertech 180 degree as the temps here for 6 months of the year are around 120 degrees F. This seems to be the only good one that Autozone has, as I have to buy it on line and have it shipped to a mates place. It dosn't have a tstat in it at the moment and during winter it runs way to cold. I'm getting a mate to bring one back here for me. Are there any other parts places worth looking at on line?

Any help would be greatly appreciated

Chris Schulz

************************************************** **89 Gt 5 speed

[HiFlow5 0]

Robert Shaw 195* stat. Works the best for me!

[red82gt]

Use a 180*, a 160* is too cold and with the temps you've seen you'll need every cooling aid you can get. Hope you've got a good 3 or 4 core radiator. Get some redline water wetter if you can.

[gtsr515]

With the temps you see, as you stated.........I would run a stock 192-195 degree MOTORCRAFT factory replacement.........

Remember to order a gasket as well

[red82gt]

If the 192 works in Florida, then it must work. Personally, I think I'd want the coolant to be moving sooner in the heat, but then again at 120*F there won't be much time with the thermostat closed anyways.

[HiFlow5 0]

Originally posted by red82gt
If the 192 works in Florida, then it must work. Personally, I think I'd want the coolant to be moving sooner in the heat, but then again at 120*F there won't be much time with the thermostat closed anyways.

Actually you want the coolant to stay in the radiator longer to cool before it circulates. If the coolant is flowing more often at a lower temp via the stat, then its not cooling down enough, and can actually cause the engine to run warmer. That's why the stock 192-195* stat is recomended, so the coolant has time to "hangout" in the radiator cool before flowing again.

[gtsr515]

Couldn't have put it better myself, The Radiator's job is to cool, and it can't cool unless the coolant is in the radiator, if it's circulating constantly it NEVER has time to cool......only absorb's heat to the point of OVERHEATING..................

jay

[cschulzy]

I'll go with a 192 degree, but I will still grab a 180 and keep in my tool box. The cooling system is stock but it has never overheated. I see alot of guys have had overheating problems but I've been lucky. Thanks for the advice guys

Chris Schulz

************************************************** **89 GT 5 speed

[red82gt]

"Actually you want the coolant to stay in the radiator longer to cool before it circulates. If the coolant is flowing more often at a lower temp via the stat, then its not cooling down enough, and can actually cause the engine to run warmer."

You guys got it backwards. When the coolant is hot, the thermostat will not hold it in the radiator for it to cool, it will be open. The thermostat holds the coolant in the block to assist it reaching operating temperature (think of the direction of coolant flow and think of where the thermostat is). The coolant will lose more of it's heat when it is moving. The 192* stock thermostat is to assist the motor getting up to optimum temperature for emissions reasons (warmer=more effective catalytic converters). I remeber when a ford engineer made a similar statement in a magazine and got blasted by several people the next month.

[HiFlow5 0]

OK, when the coolant reaches operating temp its then flows into the radiator via the stat. Then the colder coolant from the radiator then flows into the engine to keep things at a constant balance. Without that there will be over heating. The radiator is there to cool, so when the temp of the coolant in the motor reaches the temp of the stat, it opens and the cycle begins to prevent overheating.

I don't see how what I said before is backwards, it was just a basic explination. We were tying to explain why a colder stat would cause the motor to run warmer, and how a warmer stat can actually cool more efficiently.

[red82gt]

Hook up a temperature guage with numbers and tell me how often it reads less than 192*, thats how often the thermostat will be closed. Then throw you theory out. An efficient engine should run at above 200*F at all times which means that once operating temperature has been reached it will be open. The thermostat's job is to keep the temperature high enough, without a thermostat at all, the motor runs too cold and stays in open loop mode, causing it to run inefficiently. Also, the radiator will pull more heat out of the coolant when the coolant is being circulated, not when it's stagnant. Notice how if a car is shut off when the temperature is way up the coolant will start to boil just after you shut it down, not before?
Saying that the thermostat keeps the coolant in the radiator to cool it is pretty darn backward.

[Mach 1]

It starts to boil when you shut it down because it starts to depressurize, thus lowering boiling point.

I agree with you though. Once the thermostat is open, it stays open, usually. Its not going to cycle open and closed all the time to keep water in the rad. so it has a longer chance to cool.

that theory has been floting around the web, and only the mechanically uninclined are falling for it.

[red82gt]

Yeah, you're right the pressure... Wasn't thinking. either way a cooling system does it's job better when the water is flowing otherwise we could get by with a pretty poor excuse for a water pump, not to mention all those race teams using highflow water pumps would be out to lunch.

[jimberg]

You guys are still debating this?

The thermostat DOES open and close during normal operation. If it didn't, we wouldn't need a thermostat. You can actually see the point where it opens if you watch the water temp gauge. The temperature will drop periodically and then rise again.

When the thermostat is closed, it keeps all the coolant where it is. The coolant temperature in the block will start to rise and the coolant temperature in the radiator will start to drop. When the coolant temperature in the block gets hot enough, it will cause the thermostat to open allowing the coolant to flow which will allow the hotter and cooler coolant to mix and reach equillibrium at a temperature that is lower than the thermostat opening temp which causes the thermostat to close. The cycle starts over again.

The hotter the coolant is allowed to get while waiting in the block, the cooler the coolant is allowed to get while waiting in the radiator. Whether it runs too hot or too cool when you switch to a lower temp thermostat depends on the efficiency of the radiator. If you remove your thermostat, your coolant will be too cool if your radiator is better at removing heat than your engine is at addding heat and vice versa.

It would be impossible to match a radiator with an engine so perfectly that the temperature would remain static while the thermostat was open all of the time. The amount of heat your engine generates is not constant and neither is the amount of air flowing through your radiator.

[Mach 1]

Good points, but on my mustang, and a lot of others I would guess, the thermostat stayed open after engine warm up all the time, as evidenced by my coolant temperature being consistently higher than my theromstat rated temp.