Optimium engine temp?

[gotchamel]

With a 307 in a 69 c10{no a/c yet}what temp should the engine be running when warm?

Not sure what drgree thermostat I am running,open to suggestion.I live where we never have freezing temps but plenty of heat.Thanks,and what would be considered too hot?

[Frkypunk70]

I live in PA and my SBC runs at about 190. It might be differt for where you live though.
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[slikside]

I've never measured my trucks temp, but I just replaced my entire cooling system, and the thermostat I installed was a 180 degree. That's what was in it before...although it appears that for several years it probably wasn't working to well, if at all.

I can watch the temp rise until the thermostat opens, then it drops back down a needle width or so. So I would say mine normally runs at about 165?? That sounds on the cool side, but it's just a guess.

[RRR18]

I run a 205 stat in mine. Never goes higher than 215. The years that I lived in AZ I always found the the higher stats actually kept me cooler on temps. Sounds crazy but that's the way it was for me.

[ZombieWeinerDog]

is there such a thing as too cool? i wouldnt think so. mine runs at 165-180 even when its 95 out like it is today in michigan!

[danleaman]

Originally Posted by ZombieWeinerDog

is there such a thing as too cool? i wouldnt think so. mine runs at 165-180 even when its 95 out like it is today in michigan!

Yes there is, all engines have a correct operating temperature. Your local auto parts store should be able to tell you what came stock in your truck. Too cool is bad for power, mileage, will lead to acidic build up in your oil and shorter engine life. There is a reason the engineers spent all that time figuring out what operating temperature is best for your motor.

[fastwillie 696969]

Originally Posted by danleaman

Yes there is, all engines have a correct operating temperature. Your local auto parts store should be able to tell you what came stock in your truck. Too cool is bad for power, mileage, will lead to acidic build up in your oil and shorter engine life. There is a reason the engineers spent all that time figuring out what operating temperature is best for your motor.

i dont agree with the statement

[FrankieD]

I did a little searching and I found reasons to run at 180 to 205deg I copied this from another form pretty intersting. I do know if you run with no stat in warm weather you will over heat do to the fact the coolant has no time to cool off and temps continualy build. If you check out some boats they run 140deg stats you look in to the valve cover you will see moisture.

72Orange4th-December-2005, 02:58 PM
I have a 160* thermostat, and it was 40* out yesterday. Now that i have this aluminum radiator it meant my coolant temp got down to around 150* several times during stop and go driving.

I'm assuming this is too cool, but before I switch it to a 180* thermostat, what are the downsides of running too cold?

Thanks

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wskaiser4th-December-2005, 05:22 PM
One downfall of running too cool is that the oil never gets hot enough to boil out any moisture that condenses in the crankcase. You start to build up the dreaded milkshake look in the pan and valvecovers.

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Mike Goble4th-December-2005, 05:27 PM
Dr. Terry McFadden teaches a course at UAF called Arctic Engineering. It is a gold mine of tips, solid engineering, common sense and often little-known facts about coping with day-to-day problems encountered in cold climates.

If you don't like puzzles, skip the next paragraph, but I'm including it here to show the kind of problem that McFadden gives his class. It's a classic of basic engineering rationale, and requires only rudimentary mathematics and a little insight to solve. For malingerers, the answer is given at the end of this column. The problem reads:

"Some experts estimate that the wear on the rings of an internal combustion engine is as high as 0.001" per 1000 miles of operation when the oil temperature is below 170 degrees F. If the maximum allowable wear is 0.006", how long can you run your engine when the oil temperature is below 170 degrees before you wear it out?" (A 6-to-1 engine-to-wheel reduction ratio, an average running speed of 3000 rpm, and 14-inch wheels 28 inches in diameter are assumed.)

The point of this problem is to stress that by far the greatest amount of engine wear takes place before the oil is warmed up. The amount of wear that occurs afterward is insignificant by comparison.

It can be appreciated, therefore, that it is important to warm the oil, as well as the engine block. An engine that is kept warm with a circulating heater or with one that is plugged into the block can usually be started easily, but the oil is not heated and it provides very little lubrication at first. Consequently, the most engine wear occurs during the few minutes immediately after starting.

The ideal situation, of course, is to have a heater for both the engine block and the oil pan. Owners of cars with air-cooled engines like the old Volkswagen beetle know that the oil pan heaters are the only kind of heater that the engine will take (aside from dipstick heaters, and the less said about them, the better).

The answer to the problem given above is that the engine would be technically worn out after just 144 hours of cold operation. Realistically though, those 144 hours represent an awful lot of cold starts.

From http://www.gi.alaska.edu/ScienceForum/ASF7/747.html

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72Orange4th-December-2005, 05:49 PM
Thanks for the response guys.

And I've been doing some research. It seems that running too cold also leaves carbon deposits in the combustion chamber and on the valves I'll definitely be switching to a 180* very very soon.

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Mike Goble4th-December-2005, 05:54 PM
I would go straight to a 195° thermostat for winter driving. If your car runs 150° with a 160° thermostat, you want to warm it up at least 30°.

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Paul Wright4th-December-2005, 06:25 PM
I second the statements about cold operation. As noted most of engine wear occurs when the engine is cold. Despite conventional wisdom about keeping fluids as cold as possible, prolonged cold operation is not beneficial.

You are are also measuring coolant temp which may not be the whole story.
Engine oil temp should be at least 212F before running the engine hard. As noted this is to be sure to boil off condensation. 220-230F is optimum for oil viscosity and flow.
Since there is often a 30 degree difference between coolant tem and oil temp, a 195 thermostat is better for a daily driver especially in the winter months.

If you want to get something cold then cooling off intake air flow will yield performance gains.

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tpinovaII5th-December-2005, 01:57 PM
I would go straight to a 195° thermostat for winter driving. If your car runs 150° with a 160° thermostat, you want to warm it up at least 30°.

As a side note, it is well known that manufacturers use a 195 thermostat to aid in cleaner emission output. We had been swapping to 180's for years to try and have a slightly cooler intake. A friend (and fellow mechanic) had told me that a engine with 195 thermostat would burn less fuel. My dad tested this theory and said he saw an improvement in fuel economy with the 195 on every vehicle he tested.

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stricknine14th-March-2006, 03:48 AM
As a side note, it is well known that manufacturers use a 195 thermostat to aid in cleaner emission output. We had been swapping to 180's for years to try and have a slightly cooler intake. A friend (and fellow mechanic) had told me that a engine with 195 thermostat would burn less fuel. My dad tested this theory and said he saw an improvement in fuel economy with the 195 on every vehicle he tested.

Wow, these are things i never really thought about. never knew running to cold was bad.. and here i was bragging that my car never got above 155.. goes to show you learn something new every day...thanks for the info.

[RRR18]

FrankieD.....thanks for all that. Interesting.
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[steelhorse]

I personally recomend keeping it between 180 to 200 unless it is a newer fuel injected motor,then run whatever is recomended.

[danleaman]

Originally Posted by fastwillie 696969

i dont agree with the statement

That's OK it's allowed.

[AusTx68]

Originally Posted by FrankieD

...I do know if you run with no stat in warm weather you will over heat do to the fact the coolant has no time to cool off and temps continualy build.
.

I've run without a thermostat thru many Texas summers without any problems (not in my current truck). If I were to put in a 180 t-stat it would just stay open once the motor warmed. It would be equal to not having one. My current truck has a 160 t-stat but it never sees that temp in the summer. In the winter it stays at 160. Winter without the t-stat would drop temps down to 150.

[gotchamel]

Thanks,looks like mine likes the 180 mark.

[lil hoodlum]

Gosh, it has been such a long time since I replaced my t-stat. I usually just grab whatever I think my engine needs at the time. I must have grabbed a 180* t-stat because my truck runs at 180* I get very nervous if/when it gets close to 200*. I live in North Texas and we often get 100+ degrees in the summer time.

So I guess you should just run whatever degree t-stat your engine seems to run best at.

Keith

[FrankieD]

The biggest problem with running a cool engine is moisture and you will start sludging the engine up. Most of these trucks they are our toys so they don't get a lot of miles on them to get the contaminants out especially those of us that live in areas that can go from 40 to 100deg in the summer w/100% humidity and 40 to -30deg in the winter, condensation will get in the engine just sitting in the garage for 4 or 5 months. You guys in the desert don't have these problems but up north there are times when we will go out to the garage and the floor will be wet from the humidity and the engine will cover with moisture which also plays hell on aluminum parts. The oil should be changed before you put it away for the winter and in the spring because the oil will get acidic from condensation and sitting. I know some will say they have never had any problems but the price of oil is cheaper than an engine. Sorry for the rant.

[MagmaJct]

Your cooling system, radiator, fan, etc... set the maximum engine temperature. The thermostat sets the minimum temperature. Running at the proper temperature does many things, most have already been stated. One not mentioned yet is improved thermal efficiency.

When a fuel is burned it produces heat. The heating of the gases in the combustion chamber causes an expansion of the gases which produces power by exerting force upon the pistons. The cooling system removes some of this heat. Removing the heat also reduces the rate of expansion of the gas.

Earlier engines were not designed with emissions and economy in mind. They ran with cooler thermostats. With the engines running cooler gasoline vapors would condense on engine surfaces and fail to burn, and not contribute to power. But installing hotter thermostats, the internal surfaces are able to run hotter and greatly reduce gasoline condensation on engine surfaces.

This improved thermal efficiency of the engine, and allowed fuel systems to be tuned leaner since less fuel was condensing inside the engine. This also had the effect of reducing emissions, reduced the amount of gasoline finding its way into the oil. Engine wear was reduced over the model years, and modern automobiles today have much longer oil change intervals as a result.

My advice? In stock applications, use the correct thermostat for the engine installed. This should not matter what the climate is. The thermostat sets the minimum operating temperature, not the maximum. 190F is going to be the same whether it's in Arizona or Maine. The only difference is that in Arizona the thermostat will be open more than the same setup in Maine.

Most automotive textbooks cover this topic very well.

[FrankieD]

Well Said

Originally Posted by MagmaJct

Your cooling system, radiator, fan, etc... set the maximum engine temperature. The thermostat sets the minimum temperature. Running at the proper temperature does many things, most have already been stated. One not mentioned yet is improved thermal efficiency.

When a fuel is burned it produces heat. The heating of the gases in the combustion chamber causes an expansion of the gases which produces power by exerting force upon the pistons. The cooling system removes some of this heat. Removing the heat also reduces the rate of expansion of the gas.

Earlier engines were not designed with emissions and economy in mind. They ran with cooler thermostats. With the engines running cooler gasoline vapors would condense on engine surfaces and fail to burn, and not contribute to power. But installing hotter thermostats, the internal surfaces are able to run hotter and greatly reduce gasoline condensation on engine surfaces.

This improved thermal efficiency of the engine, and allowed fuel systems to be tuned leaner since less fuel was condensing inside the engine. This also had the effect of reducing emissions, reduced the amount of gasoline finding its way into the oil. Engine wear was reduced over the model years, and modern automobiles today have much longer oil change intervals as a result.

My advice? In stock applications, use the correct thermostat for the engine installed. This should not matter what the climate is. The thermostat sets the minimum operating temperature, not the maximum. 190F is going to be the same whether it's in Arizona or Maine. The only difference is that in Arizona the thermostat will be open more than the same setup in Maine.

Most automotive textbooks cover this topic very well.

[ubtripn]

Yes there is, all engines have a correct operating temperature. Your local auto parts store should be able to tell you what came stock in your truck. Too cool is bad for power, mileage, will lead to acidic build up in your oil and shorter engine life. There is a reason the engineers spent all that time figuring out what operating temperature is best for your motor.

I agree with this. Temperature and friction control has always been en engineering imperative regarding efficiency and wear. Friction vary dtermined by temp, that alone suports the above statement. With todays's vehicles it applies even more withe various sensors making sure to keep it exact. On my Nissan the temp gauge sat in the middle for so long I just thought it was broke but one day after years of driving my coolant, "wore out" or broke down molecularly and the needle rose.

[Monty]

IMO, the biggest issue we are looking at is the viscosity of the oil. cold=thick. the worst engine wear doesn't come from the oil thinning from heat, it is from getting too thick when cold.

[68gmsee]

Originally Posted by AusTx68

I've run without a thermostat thru many Texas summers without any problems (not in my current truck). If I were to put in a 180 t-stat it would just stay open once the motor warmed. It would be equal to not having one. My current truck has a 160 t-stat but it never sees that temp in the summer. In the winter it stays at 160. Winter without the t-stat would drop temps down to 150.

Yes and no. A 160° stat will more than likely run wide open all of the time here in Texas but a 180-195 may not. The thermostat will open and close slightly to allow the coolant more time to transfer heat in the radiator.

Here in Texas we've been accustomed to run as cool as possible for obvious reasons, but according to the experts the engine is more efficient and will last longer in the recommended temperature.

[sanford66]

Good info. I guess i won't be too concerned when the temp gauge in my 68 reads 190-200 when i'm driving around town. Learn something new every day on this site! Joseph

[AusTx68]

Originally Posted by 68gmsee

Yes and no. A 160° stat will more than likely run wide open all of the time here in Texas but a 180-195 may not. The thermostat will open and close slightly to allow the coolant more time to transfer heat in the radiator.

Here in Texas we've been accustomed to run as cool as possible for obvious reasons, but according to the experts the engine is more efficient and will last longer in the recommended temperature.

Just yesterday I picked up a 195 degree thermostat! Based on the info in this posting it may help my engine run cooler. My dual fans kick on at 185 so at 195 the water in the radiator should be cooler than the engine. My crusing temp in the summer is 180-185. I'm thinking with this setup my temp should stay below 200 when I get stuck in traffic.

[MagmaJct]

Originally Posted by AusTx68

I'm thinking with this setup my temp should stay below 200 when I get stuck in traffic.

And that's the key. If your new thermostat works correctly and you're overheating, the problem is not the thermostat. So many shade tree mechanics (the bad ones!) think that the correct thermostats cause over heating. How could a 195 degree thermostat that's working properly cause an engine to exceed 215 degrees if it's already wide open? It can't.

But so many people think replacing the thermostat with a colder one or removing it all together is the solution. Colder thermostats I'm sure have their place. I'll acknowledge that I don't know that place, but it's not in a stock application. Cheers!

[85_C10_Sleeper]

I run 115 degrees in 80 degree weather in traffic... used to do about 160 until I replaced the water pump. Then my temps went way down. As far as mpg goes I get 18mpg in town. I understand why it could be a problem, but I sure as h*ll haven't had any running way cooler than you guys.
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[FrankieD]

A little education won't hurt, here is an oil site :
http://www.bobistheoilguy.com/


Here is another site that talks about oil & water temp they all seem to say the same thing that to cool is bad

http://www.carnut.com/ramblin/cool3.html

HOTRODSRJ’s COOLING TIPS
Operating temperature vs power and longevity!
- - Back - -

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Home > Ramblin > Cooling Tips 3

by Steve Jack
HOTRODSRJ@AOL.COM
Concept One Pulleys
Jackstands at Old Cars Only

A few of you good folks must have spotted other articles that I have done either in print or online about this subject. At the request of a few folks here I am putting this up for what it's worth and expanding some information about this as well. The argument is about running 160 degree thermostats and the good and/or bad results. Now keep in mind that thermostats have absolutely NO effect on your systems ability to cool, simply a regulator of the range it operates in. So, if you think a 160 will cure an engine running at 220 with a 180 thermostat...forgetaboutit! This is not about cooling capacity at all.

The graph to follow illustrates the importance of how critical optimum coolant temperature is to the longevity and performance your engine. Cooler water makes horsepower and warmer water minimizes engine cylinder and bearing wear...or so it's thought, but only to their own limits and ranges. There is a range where both optimum performance as well as minimal wear share similar characteristics. That number lies in the 175-180 degree range as shown by the overlap in the chart which correspondingly requires a 180 degree thermostat. FWIW, higher operating temperatures of today's engines are to fight combustion by-products and pollution. Also, engine oils are designed to work over a specific temperature range with optimum performance starting at temperatures that require the coolant to be the very same 175ish range. And don't forget the moisture issue. Have you ever seen water vapor coming from your tailpipes? Sure..and the very same thing happens INSIDE your engine. YOur engine forms moisture inside when it cools and condensates on the walls of the inside. This moisture the is washed down into the oil when started and then awaits vaporization by internal temperatures rising enough to bring the moisture to the appropriate corrected vapor point (boiling). If enough moisture is left behind it combines with combustion byproducts to form acids that become dissolved in the oil itself. The oil becomes more acidic as the age of the oil progresses and picks on certain parts eventually. Also moisture will corrode other surfaces. So, it's important to get these engines to a satisfying operating temperature as soon as possible. Usually oil pooling temps are about 30 to 40 degrees higher than the coolant temps. This is a generalised statement and can vary with load and engine design but you can see why you want your oil over 212 degrees to boil out the moiture immediately! A 160 thermostat usually does NOT accomplish this temperature.



Years of research show use of 160 degree thermostats is way too low to be considered for performance or engine longevity. As the chart above illustrates, engine wear increased by DOUBLE at 160, than at 185 degrees. The 160's were invented for and commonly used in older, open loop cooling systems where only 6 pound radiator caps were used, and low 212 degree boiling points were the limit. We know better now.

Many early hot rodders found the 160's to be a smiggin better performing than the 190's, however the in between 180 appears to satisfy both ends of the spectrum. The correct water temperature and thus resulting metal operating temperatures required for the cylinders to achieve a minimum specific temperature in order to allow a fully mixed Air/Fuel charge to combust efficiently is a minimum of 180 degrees coincidentally. If you use 160s be aware that this can have a degrading effect over a time on your engine. I know alot of rodders still using them however to whatever ends they want...and that's okay. Heck, I know guys that run NO thermostat and most of you know that's another book to be covered. I just report what I learn...and you decide what's best for you. I hope this satisfies you information junkies out there.

Steve Jack
HOTRODSRJ@AOL.COM
Concept One Pulleys
Jackstands at Old Cars Only