EngineTemp

[55 Fargo]

Hey all, yesterday bought a new 180 t/stat, installed, added coolant started engine.

It warmed up right to 180, then opened, then I ran the engine, it was maintaining about 155-157 on the stock gauge.

I ran the engine this afternoon, for a good 1/2 hour, but just at fast idle, ,it was about 10 above outside, so not warm, but again the engine temp was sitting at 155-160.

I got out my infared temp tester, temp at gauge on head, bang on with gauge in car, temp uniform across head, temp about 171 at t/stat housing, temp about 140 or so in top of rad.

Now is this normal, is the outside ambient temp, and the fact there is no major load as would be driving down the highway, the reason my engine temp was not running at an even 180 sitting idling .

I have done a search, and no obvious answers were apparent, anyone have any ideas, or is this just the way it should be on a cold day....

BTW who runs what on their flatties 160 or 180 t/stats, and for what reasons?

[Robert Horne]

I have been running a 180 in my 38 for the past 20 years. It stays close to 180 if outside temp is not too high, like about 85.. I tried the car one very hot day, about 95 degree, letting it idle for awhile. Had a cooking temp gauge in the radiator. Car got up to 190 to 195, no boil over. .

[Niel Hoback]

I've had a 160 in mine for a good 10 years, and it runs right at 160 steady. If I run it hard, 60 mph or more, it will go to 170. It will idle all day right at 160. I really should swap it for a 180, but I just don't seem to get to it.

[55 Fargo]

I have been running a 180 in my 38 for the past 20 years. It stays close to 180 if outside temp is not too high, like about 85.. I tried the car one very hot day, about 95 degree, letting it idle for awhile. Had a cooking temp gauge in the radiator. Car got up to 190 to 195, no boil over. .

Robert, would this be the case with a 160 tstat, as on a super hot day, once opened, would it not climb to 190-195 also, or would it be lower as it opened. Thanx Fred

[55 Fargo]

I've had a 160 in mine for a good 10 years, and it runs right at 160 steady. If I run it hard, 60 mph or more, it will go to 170. It will idle all day right at 160. I really should swap it for a 180, but I just don't seem to get to it.

Hey how about you try a 180 too;), oh come on:D....

[Jerry Roberts]

Robert, would this be the case with a 160 tstat, as on a super hot day, once opened, would it not climb to 190-195 also, or would it be lower as it opened. Thanx Fred

Once your thermostat is opened , it makes no difference to your water temperature of 190-195 .

[55 Fargo]

Once your thermostat is opened , it makes no difference to your water temperature of 190-195 .

This true Jerry, with a 180 t/stat, it will be maintained closer to 180, then rise from there on hot days, and may sit at 190-195.

A 160 t/stat on hot days will open near 160 degrees, and sit at says 175-180, or if the engine is not working too hard, and the ambient temps are not too hot, it may sit around 160-165.

My concern is running too hot only yon the hottest days, I have not had boil overs, even when the gauge would read close to 200, on a few occasions. On those super hot days, my main concern is fuel issues, fuel pump, vapor locks, have had this issues, when under hood temps reached sky high, this could happen with coolant temp of 175. My oil pressure will drop a bit at idle on hot days, and when engine is running warmer too, that is normal for my un-rebuilt engine...

[Jerry Roberts]

[quote name=Rockwood; ...< snip > with a 180 t/stat' date=' it will be maintained closer to 180, then rise from there on hot days, and may sit at 190-195.

A 160 t/stat on hot days will open near 160 degrees, and sit at says 175-180 ... <snip > [ unquote ] Nope , not correct . With the thermostats open , the high temperatures will both be the same .

[TodFitch]

...snip.. with a 180 t/stat' date=' it will be maintained closer to 180, then rise from there on hot days, and may sit at 190-195.

A 160 t/stat on hot days will open near 160 degrees, and sit at says 175-180 ...snip...[/quote'] Nope , not correct . With the thermostats open , the high temperatures will both be the same .

I agree with Jerry here.

My old Chiltons says that a thermostat should be 1/2 open at the temperature it is designed for. So on a cold day with the cooling system in good shape and no load on the engine you should be a little below 180F with a 180F thermostat because there is more than ample capacity to remove the waste heat from the engine without full flow through the thermostat. Under load on a warm day you should be a little over 180F because there is enough heat being generated that you need full flow through the thermostat. But once fully opened it does not matter if its a 160F or a 180F thermostat so the maximum engine temperature should be the same.

[55 Fargo]

I agree with Jerry here.

My old Chiltons says that a thermostat should be 1/2 open at the temperature it is designed for. So on a cold day with the cooling system in good shape and no load on the engine you should be a little below 180F with a 180F thermostat because there is more than ample capacity to remove the waste heat from the engine without full flow through the thermostat. Under load on a warm day you should be a little over 180F because there is enough heat being generated that you need full flow through the thermostat. But once fully opened it does not matter if its a 160F or a 180F thermostat so the maximum engine temperature should be the same.

This makes sense to me, but on a cold day up here is a weee bit different than what you Guys view as cold.

Let me explain, the other day it was near 0 f, and after I installed the 180 t/stat, my engine immediately warmed to 180, the t/stat opened, and then the engine, because of idling with no load sat about 155-160, but would no doubt have risen to 180 or near, on a drive at 60 mph.

But I can tell you, if it were -20f, and you went for a ride, this t/sat would probably not be open too wide, as any coolant entering the rad, would be cooling down in a "New York Minute",.

I am in the belief my engine will run around 180-185 with a 180 t/stat this summer, except those really hot days, maybe 190 or so.

Now there has been much discussion, and Greybeard's "Thoughts On Mopar Flatheads 2 ", suggest, running at lower engine temps of 160-170, can have a negative effect on the engine, and our engines should be run at 180-200, for optimum performance and longevity. I am not 100% convinced of this on our engines, but am not refuting it either.

My main agenda, was to generate some discussion on which t/stat temp range would be the best, as per anyone's experience on this forum.

To repeat, I understand a 160 or 180 t/stat is a measurement of at what temp the coolant will rise, until the stat opens and allows the coolant to flow. Some of our members feel the higher margin of degrees between 160 and 200 is better on those days where temps can build easier and quickly.....

[Young Ed]

Some of our members feel the higher margin of degrees between 160 and 200 is better on those days where temps can build easier and quickly.....

Yup thats me. I also believe long trips and regular oil changes with modern oil and unleaded gas will prevent most of the sludge found in older engines.

[Dan Hiebert]

I have a 160 degree thermostat in mine. Bought the car when we were living in El Paso, TX and when I went through the engine the first time I installed a 180 first (didn't even have one when I got it). It was so blasted hot all the time the system couldn't catch or keep up with the 180, so I installed a 160, and there it still is, and haven't had a problem since. It has always run right around 160, even once we moved north. It would creep up to around 180 on really hot, still days, or when going up hills, but always tapers off. The car doesn't have a heater, so there's no affect on that (not that there would be much of a difference made with the thermostat setting).

[Dodgeb4ya]

I run 160 degree thermostats on my old MoPars. I have one in my 51 Plymouth that I rebuilt the engine back in 1968. It has about 70,000 on the engine. There is no sluge in the tappet chambers as about a year ago I did a valve adjustment on it. I do/did change the oil on a 3000 mile schedule and always used the same brand oil. Most all of my vehicles have rebuilt engines, and no sludge in any because of good oil changes and using the same brand of oil each change.

I don't worry about the 160 degree thermostat and sludge.

Bob

[55 Fargo]

Just warmed engine up, t/stat opened at 172 or so, then went for a 5 mile drive, engine temp after the t/stat opened, on my drive was in the 155 range. It isa clear cold morning of -2f, so in cold weather it would be vitally necessary to have a 180, but on hot days, don't think so.

I may swap to a 160 this week, or wait until it is warmer in the driving season, I may not be able to start driving my car until another month anyway, by then temp should be 50s and 60s...

[55 Fargo]

I run 160 degree thermostats on my old MoPars. I have one in my 51 Plymouth that I rebuilt the engine back in 1968. It has about 70,000 on the engine. There is no sluge in the tappet chambers as about a year ago I did a valve adjustment on it. I do/did change the oil on a 3000 mile schedule and always used the same brand oil. Most all of my vehicles have rebuilt engines, and no sludge in any because of good oil changes and using the same brand of oil each change.

I don't worry about the 160 degree thermostat and sludge.

Bob

The key word, clean engine to begin with, and regular oil changes= cleane,sludge free engine. As the old Fram TV commercial, "pay me now, or pay me later".....

[55 Fargo]

Okay, call me impulsive, went out and installed a brand new 160 t/stat, the Permatex RTV for t/stat housings is curing. Will fill tomorrow, and test, not sure I need to let the permatex dry 24 hours before I refill the system, but it is only 50 in the shop.... nest task, is pulling pumpkin from diff for new gasket and pinion seal, will have it inspected at a shop too....

[Don Coatney]

Fred;

You have been given some very good information in this thread. In my opinion the biggest benefit for running a 180 stat is your engine will reach a better operating temperature quicker. And in my opinion the better operating temperature is 180 or higher for the reasons stated above. As has been said once the thermostat is fully open the thermostat is out of the equation and the efficency (or lack of it) of your cooling system takes over.

Now having said that I must admit my hypocrisy. When I built my engine I had in my stash a working 160 thermostat and that is what I installed. It is still in my engine today. However on really cold days my engine will not come up to full operating temperature as long as my car is traveling over 30 MPH. I do not have a belt driven cooling fan but instead a thermostically controled electric fan. I have the thermostat set to turn the fan on at slightly over 180. If on a cold day I am sitting at a stop light for an extended period of time my fan will turn on and drop the engine temperatue quickly. In the middle of summer when the ambient temperature is over 90F my electric fan runs continually with the car not moving. And on days like this I have seen my temperature gauge climb to over 200. But once I am moving the temperature drops and the fan shuts off. Freeway driving on summer days at 70+ MPH my fan never runs. But as soon as I slow down the fan kicks on but the temperature gauge climbs quickly and will shoot to 200 for a short time. I do notice that if I am pulling a long steep grade my engine temperature will climb and my fan will kick on. Once I got stuck behind a farm tractor while going up a steep hill for several miles. My electric fan kicked on but the temperature kept climbing and went over 210 but did not boil. Once I crested the hill and passed the tractor the engine temperature dropped below 180 and the fan shut off.

I do have a new 180 stat that I will install someday. But I can live with my system the way it works now. It aint broke etc.

[55 Fargo]

Fred;

You have been given some very good information in this thread. In my opinion the biggest benefit for running a 180 stat is your engine will reach a better operating temperature quicker. And in my opinion the better operating temperature is 180 or higher for the reasons stated above. As has been said once the thermostat is fully open the thermostat is out of the equation and the efficency (or lack of it) of your cooling system takes over.

Now having said that I must admit my hypocrisy. When I built my engine I had in my stash a working 160 thermostat and that is what I installed. It is still in my engine today. However on really cold days my engine will not come up to full operating temperature as long as my car is traveling over 30 MPH. I do not have a belt driven cooling fan but instead a thermostically controled electric fan. I have the thermostat set to turn the fan on at slightly over 180. If on a cold day I am sitting at a stop light for an extended period of time my fan will turn on and drop the engine temperatue quickly. In the middle of summer when the ambient temperature is over 90F my electric fan runs continually with the car not moving. And on days like this I have seen my temperature gauge climb to over 200. But once I am moving the temperature drops and the fan shuts off. Freeway driving on summer days at 70+ MPH my fan never runs. But as soon as I slow down the fan kicks on but the temperature gauge climbs quickly and will shoot to 200 for a short time. I do notice that if I am pulling a long steep grade my engine temperature will climb and my fan will kick on. Once I got stuck behind a farm tractor while going up a steep hill for several miles. My electric fan kicked on but the temperature kept climbing and went over 210 but did not boil. Once I crested the hill and passed the tractor the engine temperature dropped below 180 and the fan shut off.

I do have a new 180 stat that I will install someday. But I can live with my system the way it works now. It aint broke etc.

Thank you very much Don, I certainly can see how on real cold days, even a 180 t/stat would have some fun keeping the temp close 180, while moving along at speed.

Yes there has been excellent information,I will see how things go once it warms up again, cuz it is still cold here, although it is a lot nicer this afternoon, than it was in morning...

[adam_knox]

So what I'm not understanding is why the engineers designed our cars to have both thermostats as options. I guess I'm just not understanding when is it appropriate to run one and not the other. Is it just to get hot water to the heater core so we can have warm air blowing from our heaters sooner? Or is there some greater purpose that is not listed in the manuals I'm reading?

[55 Fargo]

So what I'm not understanding is why the engineers designed our cars to have both thermostats as options. I guess I'm just not understanding when is it appropriate to run one and not the other. Is it just to get hot water to the heater core so we can have warm air blowing from our heaters sooner? Or is there some greater purpose that is not listed in the manuals I'm reading?

Well it's like this, according to some folks.

160 t/stat to be used in summer weather, for a greater margin of temps getting near boil over, using water.

Or when using alcohol based antifreeze, a 160 t/stat was used to prevent boiling out the alcohol antifreeze.

180 t/stats were used in winter for faster warms ups, warmer engine temps when running in cold weather, used in conjunction with permanent glycol based coolants.

I don't know why the lower t/stats, most likely the fact water was used so much of the time, so lower boiling points.

In summer on a hot day, a 180 t/stat, might sit at 180-190, while an engine with a 160 t/stat may be run slightly cooler at 160- 180, but on a real hot days, once the t/stat opens, both are gonna run warmer than the temp of the t/stat, especially on the highway, or pulling hills, the same effect can be idling a long time, or driving very slow in traffic jams....

[adam_knox]

Thank you kind sir for your concise explanation! =)

[55 Fargo]

Thank you kind sir for your concise explanation! =)

Adam, no problem, not sure how accurate I am, tried to be clear and concise, according to what I know about the subject.....

[TodFitch]

So what I'm not understanding is why the engineers designed our cars to have both thermostats as options. I guess I'm just not understanding when is it appropriate to run one and not the other. Is it just to get hot water to the heater core so we can have warm air blowing from our heaters sooner? Or is there some greater purpose that is not listed in the manuals I'm reading?

In the old days a lot of people still used alcohol based anti-freeze solutions. If you use those in a system with a 180°F thermostat, the alcohol will evaporate out and then your engine was unprotected against the cold.

[YukonJack]

So what I'm not understanding is why the engineers designed our cars to have both thermostats as options. I guess I'm just not understanding when is it appropriate to run one and not the other. Is it just to get hot water to the heater core so we can have warm air blowing from our heaters sooner? Or is there some greater purpose that is not listed in the manuals I'm reading?

Here is my understanding of thermostats. 160 is lower operating temp in the summer, but you will get very little heat in the winter. 195 gets you nice and toasty in the winter but runs a bit hotter in the summer. 180 is the best of both worlds, you get ample heat in the winter and not running that hot in the summer. I have personally experienced all of these conditions here in Chicago. From what I have read over the years, in a properly operating cooling system the thermostat opens and closes as needed. When it opens the cooler water in the radiator flows into the engine as the hotter water flows into the radiator. The cooler water in the engine then causes the thermostat to close, allowing the cooler water to heat to the temp of the thermostat and keeping the hot water in the radiator so that the fan has a chance to cool it. The cycle continues. Hot rodders in the 60's & 70's would remove thermostats to try and run cooler but the water (coolant) ran unrestricted through the radiator not having a chance to stay in the radiator to cool down. Several aftermarket performance companys make restrictors that replace the thermostat with a block off plate with a small hole in the middle. I'm sure some people will disagree with me.

Edited April 18, 2011 by YukonJack

[Don Coatney]

Hot rodders in the 60's & 70's would remove thermostats to try and run cooler but the water (coolant) ran unrestricted through the radiator not having a chance to stay in the radiator to cool down.

I recall as a kid in the 50's watching my neighbor build his flathead ford stock car for circle tracks. He would weld a large washer into the goose necks (there are two on a flathead ford) to restrict the water flow. His theory was the water did not stay in the engine block long enough to absorbe the heat so he added these restrictors to reduce flow.

Anyone know which theory is correct?