why is it bad for a car to not reach normal operating temperature
10-05-2010, 04:42 PM
#1
2nd Gear Member
Thread Starter
Join Date: Jun 2006
Location: PA
Posts: 213
why is it bad for a car to not reach normal operating temperature
the previous owner installed a 160 degree thermostat. Needless to say the heat isn't very good and the car never reaches a normal operating temperature. only one line on the needle during most weather, 2 lines on the hottest of summer days, I also am running an electric fan.I hear its bad for a car to not reach normal operating temps, can anyone explain to me why? I'm just curious and feel like learning something haha.
10-05-2010, 04:47 PM
#2
6th Gear Member
Join Date: Nov 2006
Location: Spfld, MA
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well, basically, computer controlled engines require a certain temperature to reach optimum settings. if you can't reach that temperature, the computer will remain in what is called open loop, which is basically a strategy that runs without input from certain sensors because the engine isn't hot enough. as this happens, the computer is constantly adjusting the engine to become more lean(very dangerous), trying to get it to warm up. not only are you actually causing harm to certain sensors by staying in open loop, you're losing gas mileage, and power. The computer will pull fuel pulse width out of the injectors to try and make the engine more lean, to heat it up. As this happens, you're losing fuel economy and power.
10-05-2010, 04:50 PM
#3
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Join Date: Jun 2005
Location: Michigan
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It's because when the metal heats up it expands. The engineers at Ford design engines with certain tolerances in mind and that is taking in to account proper operating temperature. So the block doesn't expand to it predetermined size, and thus will cause undue wear and tear at an accelerated rate.
Secondly, is for the fuel infection. Since the car never gets to operating temp it will dump more fuel, this not only burns more gas, it puts out more greenhouse gases so, obviously, it is bad for the environment. IT'll run rich all the time, which is actually bad for performance. Ever heard the term "Lean is mean"?
What radiator do you have in it? I know with the stock one, mosts 5.0L Mustangs with 160*F T-stats will overheat after a little bit of driving. Reason being is that the coolant doesn't typically have enough time in the radiator to transfer off the heat it's carrying from the engine.
I usually don't recommend anyone running a 160*F T-stat up here in MI. 180*F is the coldest you should go for a DD if you want to avoid overheating.
Secondly, is for the fuel infection. Since the car never gets to operating temp it will dump more fuel, this not only burns more gas, it puts out more greenhouse gases so, obviously, it is bad for the environment. IT'll run rich all the time, which is actually bad for performance. Ever heard the term "Lean is mean"?
What radiator do you have in it? I know with the stock one, mosts 5.0L Mustangs with 160*F T-stats will overheat after a little bit of driving. Reason being is that the coolant doesn't typically have enough time in the radiator to transfer off the heat it's carrying from the engine.
I usually don't recommend anyone running a 160*F T-stat up here in MI. 180*F is the coldest you should go for a DD if you want to avoid overheating.
Last edited by P Zero; 10-05-2010 at 04:53 PM.
10-05-2010, 05:01 PM
#4
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Join Date: Jun 2006
Location: PA
Posts: 213
yeah i figured i was losing mpg, thanks guys. I'm getting around 11-12 at best. The rad looks to be stock, My stang is a 4cyl conversion using everything from an 89 5.0 mass air car as its donor, not sure if the rad was in the car or not before the conversion though. The fan actually looks like it may have been a factory 4cyl electric fan, if they came so equipped.
10-05-2010, 05:05 PM
#5
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Join Date: Jun 2005
Location: Michigan
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yeah i figured i was losing mpg, thanks guys. I'm getting around 11-12 at best. The rad looks to be stock, My stang is a 4cyl conversion using everything from an 89 5.0 mass air car as its donor, not sure if the rad was in the car or not before the conversion though. The fan actually looks like it may have been a factory 4cyl electric fan, if they came so equipped.
If it's only about an inch thick, then it's the stocker.
10-06-2010, 11:03 AM
#10
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Join Date: Apr 2008
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There are multiple reason not to run it too cold. Open loop is probably the most important. But if you use an aftermarket tuner, you can keep the lower temps and still run in closed loop. 195* is strictly for emissions. Before that, nearly all SBF's used a 180* stock.
SOmetimes there's power to be gained with the colder temp. I have seen many tests where the Corvettes really benifit from this. The Mustangs don't seem to be as sensative to coolant temps. Which is good, as that means it's more efficient than the corvettes. Probably has to do with engine bay size. In any case, there's probably no performance advantage to runnin it much below 180*.
Cylinder wear is increased at temps below 160*. You'll be doing a rebuild sooner.
And, oil temp tends to follow coolant temp. Oil functions properly at around 180* and up. Below that, the anti wear, detergent, and viscosity properties are not where they should. 40 weight oil is measured hot, at 100*C (212*F). At 150-160*, the oil is probably more like a 50 weight oil. And that's not a good thing.
Some people say that if the oil doesn't get above 100*C water won't be boiled away. That's rediculois. If that were true, your kitchen floor would never be dry. Water will evaporate at lower temps, it just takes a little longer. That's the reason the service manual recommends changing the oil more often if all your trips are short.
If it were my car (and it's not), I would do these things:
1. Check the gauge for accuracy. You could install an Autometer gauge. But, once the engine if full warmed up and the fan is off, use an infrared thermometer on the thermostat housing. No perfect, but pretty close. I'v checked mine that way, and it matches the AM gauge pretty closely.
2. Use an aftermarket tuner to take advantage of the lower temps.
3. Replace the 160* thermostat with a 180* high flow unit. Be sure to drill a 1/8" hole in the base plate to make it almost self burping. Some thermostats come that way.
SOmetimes there's power to be gained with the colder temp. I have seen many tests where the Corvettes really benifit from this. The Mustangs don't seem to be as sensative to coolant temps. Which is good, as that means it's more efficient than the corvettes. Probably has to do with engine bay size. In any case, there's probably no performance advantage to runnin it much below 180*.
Cylinder wear is increased at temps below 160*. You'll be doing a rebuild sooner.
And, oil temp tends to follow coolant temp. Oil functions properly at around 180* and up. Below that, the anti wear, detergent, and viscosity properties are not where they should. 40 weight oil is measured hot, at 100*C (212*F). At 150-160*, the oil is probably more like a 50 weight oil. And that's not a good thing.
Some people say that if the oil doesn't get above 100*C water won't be boiled away. That's rediculois. If that were true, your kitchen floor would never be dry. Water will evaporate at lower temps, it just takes a little longer. That's the reason the service manual recommends changing the oil more often if all your trips are short.
If it were my car (and it's not), I would do these things:
1. Check the gauge for accuracy. You could install an Autometer gauge. But, once the engine if full warmed up and the fan is off, use an infrared thermometer on the thermostat housing. No perfect, but pretty close. I'v checked mine that way, and it matches the AM gauge pretty closely.
2. Use an aftermarket tuner to take advantage of the lower temps.
3. Replace the 160* thermostat with a 180* high flow unit. Be sure to drill a 1/8" hole in the base plate to make it almost self burping. Some thermostats come that way.