Hi 73Delta88, All

Starting from the top.


Stat is defective, replace it.

If it's the correct part for the application, and it's working correctly, your temp will go directly from cold to normal in a short time.

What constitutes "normal" and "a short time" is determined mostly by the outside temp.

Regards, Norm

Edit: stat may not be defective, depending on the location of the temp sending unit.

Hi onionman, All,

This is for anyone who reads my posts:
Fact ....... opinion They are not interchangeable.


This belongs in a thread where an opinion is being discussed.


Yes. On the street it's not common practice, but it is done. If one encountered a problem, the stat would not be the cause.


No. Few, possibly none (other than street only type cars) use thermostats in competition.


Cooler ambient temps, yes. Thermostat is not a factor.


If you used a 160, 180, 200, 250, or a 400 degree stat and you were driving in sub freezing temps, I'm confident your gauge would never move.


I believe everyone should have the freedom to do whatever they want to their own car with out being insulted or called names.

But, I digress

To paraphrase what I've said many times: If you think it looks cool, go for it. Don't just make a change because someone said it'll get you 600 HP.

Regards, Norm

Hi speedy266, hello all,


If we believe the article, cracked heads are quite common, as drilling 2 small holes in an eleven dollar thermostat is quite uncommon.


Stat is defective, replace it.


Blocking the airflow thru the radiator will raise coolant temps in the heater core and better heat the interior.

Regards. Norm

Edit: stat may not be defective, depending on the location of the temp sending unit.

Hi 88 Coupe
What makes you think the stat is defective if its operating like that?

Hi 88delta88, All,


Your stat is not a factor.
If a low ambient temp keeps the coolant under 100*, your heater output will feel cool.

If something other than the stat limits the temp to a point lower than its design, it will have no effect on anything.

Thermostats are designed to to bring the coolant up to operating temp as quickly as possible and to maintain that temp. Nothing more, nothing less.

Target operating temp is determined by the value (140*, 180*, 205*)of a particular stat.


Sounds familiar

Regards, Norm

Hi speedy266, All,


Not a good way to phrase a question, but it is an excellent opening for a pissing match. I assume the latter not to be true.

Check my last. I was composing/editing it while you posted.

If you don't see the answer there, ask again, but rephrase it.

An example might be ........... Please explain why it's defective?

Then I might describe how it should work (should be in my last post) if it were not defective, and then I might go on to tell you how you can verify its condition for yourself.

Regards, Norm

No pissing match here, I can tell you though my stat is not defective cause its been like that all winters from all that stats ive went through. Though no two stats are alike, some just start to open at the specified temp, others are fully opened by that temp. I use a 195F from ac delco in the winter, which is probably not opening fully until higher than 195F. A hypertech 180F in the summer months that is probably fully opened by 180F.

Makes sense to me in the winter if youve got -20C coolant in the rad, while the engine is warming up and your driving the cold air is blowing on the rad and the coolant is getting even cooler, so when the stat does open the temps will drop alot. Same cylce cold air cooling the hot coolant, it will never have a chance to get to the temps that it does in the summer.

Hi speedy266, All,

Sorry I took so long to get back.


Until I know more about how cooling systems/thermostats react below freezing, I’ll reserve judgment.


If a 160 were to start opening at 160, it would be fully open at 180 or higher, and I would think the factory would rate it at 180 or higher.


If ones car runs its best at 180, seems like a 180 is what one would use all year round.


This is where I have my problem.

If the stat snapped open, there would be a sudden drop in temp and the risk of damage to the engine.

If it were to open gradually, as it was designed to, the mixture of the hot and cold liquids would be equalized. The amount if time would vary with the outside air temp.

The cold liquid passing through the stat causes it to close quickly enough to allow the temp equalization to take place.

The above is not much more that the basics that can be found here.

If something else happens in under freezing temps, I need an explanation.

Regards, Norm

The only reason why i use two temp stats during summer and winter is cause, well in winter anything lower than 195F will cause longer warm up times and not enough heat inside the car. In the summer though 195F will provide the best fuel mileage, but a 160F or 180F will keep the engine cooler in the hot summer months which burns more fuel for more power.

Temp gauges on all cars are different, ive noticed on GM cars u can easily tell when the stat is opening because of a quick change in the needle. As for a Nissan once it warms up to its right temp, the guage never moves from that one spot, its not accurate at all at it says it H and C, on a cold winter day it will stay there on a hot summer day idling with the rad fans on it will stay there.

In winter the stat does not open as frequent because of of the longer time it takes for the engine to heat up the coolant with the surround temp so low.

Im sure you know about windchill
http://www.nws.noaa.gov/om/windchill/index.shtml

On a day where the temp is -5F and ur driving 60mph on the highway the rad is actually experiencing temps of -40F blowing on it. If the coolant in the engine is 200F when they mix they'll be a big change. When mixing to temp liquids the temp equalization is not instant. If cold coolant is coming in from the lower rad hose, all the hot coolant in the engine will leave passing by the stat keeping it open until some cold coolant has a chance to close it. If the temp guage sensor is places near the stat it will not move much at all, if it is places closer to the lower rad hose it'll move alot.

Hi speedy266, All,

The coolant for the heater/defroster comes directly from the engine, so it gets warm and then cold?


It would take longer to bring the temp up to 195 than it would to bring it to 180.


My understanding is, the stat, when working correctly, will not allow the quick drop in engine temp to happen as you've described. I’ve never seen a stat, in proper working order, react differently.

I am not happy when I don’t understand why a mechanical device doesn’t do what I think it’s supposed to.


In the Los Angeles Basin, windchill is how we get temps that are below freezing.

I didn’t think about it, but if it is factored in, my experiences have been with even lower temps and I’m more confused.


If the pump is circulating hot coolant past the stat, returning it to the engine, and heating the incoming liquid, the drop should not happen.


The turbulence caused by the pump should make the heat transfer almost instant.


Because it reflects the actual engine temp.


It will show the inlet temp, instead of the actual engine temp.

I believe I have made sense. Where did I go wrong?

Regards, Norm

Anybody?

Well ideal temp that GM pretty much puts on all there cars is 195F, reaching a constant 195F is hard enough with a 195F stat, with a 180F it will probably never get to 195F.

If the thermostat was placed by the lower rad hose when its bathed in cold coolant than needle changed would be slight because the stat wouldnt be open for long at all, the second it would open cold coolant over it would close it in 2 seconds.

All cars have thermostats in different locations and different length lower and upper rad hoses, also coolant temp sensors in different locations so its hard to compare 2 cars or even stat facts in general.

So youve had experience in real cold weather, with which kinds of cars may i ask?

The pump is circulating hot coolant by the stat, and in winter months cold coolant will be coming back into the engine, temperature effects is not a linear line, as you get colder its an expoential curve. Heating is not instant it takes time to heat the cold coolant. Same with mixing two liquids even with turbulence, it will never be instant. Times vary depending on the temp range of the coolant, in the summer months the coolant in the engine and the coolant in the rad have close temp ranges. In winter months because of the expoential effect the temp differences can be quiet large, longer time it takes for the engine to heat the coolant in the engine because everytime the stat opens its pretty much like the stat is opening for the first time in the summer.

Like i said placement of stat and sensor has a big affect, depends on the car uve had experience with and where its located on those cars, the sensor should not be placed near the upper (stat) hose or lower hose, both wont show actual engine temps, upper will show outlet coolant temp, lower as u said will show inlet coolant temp. it should be places equal distance from both hoses.

My ciera has to outlets from the water pump one to the heater core and the other to the intake manifold. right as it enters the intake manifold i have 3 sensors for coolant there, one for my guage, one to let the ECM know the temp and the 3rd for the fan switch.

What kind of winter temps have you had experience with?

Hi speedy266, All


Cooling systems in all American cars, beginning in 66, were designed to run at temps over 212. That’s where they run unless outside temps, component wear/deterioration, or modifications, prevent it.

Stat cannot prevent temp from going higher than its rating; it prevents it from going lower.


Agreed.


Stats and sensors should be placed in the best position to show the exit temp.

I am not trying to compare different car designs, I’m trying to learn how cooling systems react differently below freezing temps than they do above freezing and how that reaction led me to believe you had a defective stat, when you did not.


I have lived in Southern California all my life. No experience with temps below freezing. That’s the reason I’m trying to understand how/why automotive cooling systems react differently below freezing than they do above it.

My response to your windchill reference was not clear. I should have said “I am familiar with the phenomenonâ€

Im not sure what you do or do not know about windchill, you could read up on it, but bascially a higher windchill factor is going to cause anything to cool down faster.

I meant by passing through the stat sorry.

Heres how my setup is, Lower rad hose to pump, pump has 2 outlets, one to the intake manifold, other to the heater core. Heatercore line bypasses the thermostat, and is pretty much connected back to the upper rad hose. The other coolant soaks up block heat, and flows out through the uppers rad hose.

I think ive refered to the cardboard on the grille, people in colder climates do it so the coolant in the rad doesnt cool down to fast and never let the engine get to operating temp, and operating temp as u said is around 212 doesnt bring enough heat into the car.

Hi speedy266, All,


Windchill is a simple concept and I have been aware of it since I was a small 88. How it works was explained fully in science I in high school.

I have driven 80 and 100 mile on a predawn winter day with nothing but cool air from my heater.


Your explanation of the mechanics of heat transfer is a good one, however it does not explain how the stat allows cold liquid to enter in a large enough quantity to cause such a large temp drop.



Your setup is not much different than anything else I’ve seen, except the pump normally has three inlets and one outlet.

The one to the manifold is the Bypass hose (It allows hot coolant to bypass the thermostat for circulation back into the engine) and is from, not to, the manifold.

The one to the heater is actually from the core to the pump. The hose to the core is pretty much fed from and is connected around the upper radiator hose where the hottest available coolant is found.

The other coolant soaks up block heat, mixes with the above, and the resulting recirculation restricts flow of the cold liquid from the radiator. This allows it to be preheated before it reaches the hottest area of the engine, the heads. The mix then flows out the upper hose and into the radiator.
Exception is SBC. Difference is, the stat is bypassed via a heater hose.


And as I replied then, I’m familiar with the practice of blocking the airflow through the radiator. I have done it myself, but for different reasons.

Regards, Norm