How cool is too cool?

SeaCorey · Feb 19, 2013

Thanks for the replies to "Snapped water pump stud, now what?", I've got a few hundred miles on her with the new water pump and it's running real cool - maybe suspiciously cool.

Any chance it's running too cool to get out of warm-up mode?

Will the computer throw a code if the coolant doesn't get hot enough?

I flushed the block and radiator real well, put in a gallon antifreeze and two bottles Amsoil coolant boost (which calls for 1 bottle with 50/50 mix antifreeze/water or 2 bottles with straight water), as well as switched to 180* thermostat. I made a 300 mile almost all highway miles roadtrip and got 19mpg, then a day later made a 100 mile almost all highway round trip on a cold night (under 60 is cold for us here in Tampa) and got 15mpg. Same fuel, same driving style, took it easy, kept it under 80, same weight in the car, seemed to be running the same both trips. The heater blew heat, and the temp gauge barely gets above the 1st hash past 130, which is about where it's been since I put it all back together.

Thanks

Gearbanger 101 · Feb 19, 2013

It's the thermostat that's doing it, not the water pump. Put the stock thermostat back in. There's no need for a 180* thrmostat in a stock EFI car. Your mileage will improve, your oil will stay cleaner, longer and you'll put less more emmisions.

Bill Gordon · Feb 20, 2013

If you can get your hands on an infrared thermometer take a reading on the inlet manifold behind the tstat housing and compare it to what your gauge reads. Stock gauges are usually way off.

HISSIN50 · Feb 20, 2013

Agreed that a real reading needs to be taken before doing any diagnostics. You can interpolate the ECT if you don't have an aftermarket gauge or IR thermo'.

Gearbanger 101 · Feb 20, 2013

if the cars dummy gauge ran in the "normal" ranges before the thermostat swap, and it now doesn't after the swap, I don't see where the mystery lies? It's a $5 part....I say swap it back and consider it lesson learned.

clement · Feb 20, 2013

its possible you got a 160*. on cool days with the 160* mine will sit at 130-140*. with the 180* mine runs at 160-170*. since you live in FL i would leave it alone because when it heats up this summer itll run fine with the lower temp t stat. this whole 'run it hot' deal i dont agree with. back in the day when we had sludge for oil maybe, but all you are doing running it hotter is making it more prone to preignition when you live in an environment that is 100*+ with 80% humidity.

ratio411 · Feb 20, 2013

I think your gauge may be wrong.
We run 160* stats in our 5.0s here in Florida, and the vehicles with electric fans run 170ish by mechanical gauge in normal driving, a bit more in heavy traffic since the fans don't come on until the temp is much higher.
A mechanical fan will tend to run them cooler as it never stops spinning, but it shouldn't spend any time below the stat temp (once it is totally warmed up), assuming the stat is not stuck open for some reason.
The fact that your heat blows hot tells me your gauge is probably wrong, by itself.

Gearbanger 101 · Feb 20, 2013

clement said:
its possible you got a 160*. on cool days with the 160* mine will sit at 130-140*. with the 180* mine runs at 160-170*. since you live in FL i would leave it alone because when it heats up this summer itll run fine with the lower temp t stat. this whole 'run it hot' deal i dont agree with. back in the day when we had sludge for oil maybe, but all you are doing running it hotter is making it more prone to preignition when you live in an environment that is 100*+ with 80% humidity.

Well, see...it seems you basically agreed with me without intending to.

If you live in an environment that regularly see's 100F+ temps, then going to a 180F thermostat is warranted, as you'll still reach normal operating temperatures with it. For the rest of North America where seasonal ranges are spent mostly in the 60-85F range, the stock 192F thermostat remains ideal. He’s in Tampa…where temps seasonally run exactly in those ranges listed above. In which case…is well within the spectrum of the stock T-stat.

Running cold thermostats was an old school carbureted trick. It doesn’t work with EFI vehicles...never has. That myth goes right along with TPS sensor adjustment, playing with fuel pressure on a stock vehicle and plugging the EGR coolant lines. It simply doesn't work and in a lot of cases does more harm than good. I'm not saying it won't run, or drive well, but the vehicle must reach operating temps as quickly as possible and remain there consistently for the ECU to function properly. Heck....factory cooling fans don't even engage below 200F for just this reason.

The only time a cooler thermostat is of any benefit is in the case of an engine with large displacement or high heat performance enhancements, etc that warrant it, or in the case of an environment where heat soak is a problem such a climate where high ambient temperatures are the norm, hot lapping at the race track, regular heavy stop and go traffic in low airflow situations, etc.

As I said....running the system under its recommended temp causes problems. Dirty oil, condensation, stinky exhaust, high emissions, poor mileage. It's been well documented numerous times throughout the years.

clement · Feb 20, 2013

when my car was stock in the mid 90s, with a 180* in 20* weather it still got up to 170* which is more than enough to go into closed loop. so lets just agree to disagree on that. so mpg shouldnt suffer. when my car was stock with a 180* it used to get 24mpg hwy. after putting the turbo kit on it in 1998 the mpg went up to 27 mpg hwy. if its a daily driver that sees no performance use, ok i see your point about not running a low temp (160*) or restrictor. in terms of oil, with the 5w30s that flow like water the oil temp is going to get to operating temp even with a low temp t stat if the car is driven for any length of time. an oil temp gauge will verify that. in a performance application there is good reason for running a low temp t stat; resist preignition. not to mention some local builders that go by the name reher morrison profess this same thing. in terms of running them cold not working with eec4, i have seen .2 improvement in the 1/8 running one cold in open loop vs. running at 190*. im to the point that i can give a crap if my 20 year old fox body gets good mileage, but i guess i was under the assumption we drive V8 cars for performance. perhaps i am mistaken.

Gearbanger 101 · Feb 21, 2013

clement said:
when my car was stock in the mid 90s, with a 180* in 20* weather it still got up to 170* which is more than enough to go into closed loop. so lets just agree to disagree on that. so mpg shouldnt suffer.

The degree at which fuel mileage suffers may be minimal at that level, but what about oil cleanliness, moisture, contamination, carbon deposits and emissions levels? A hotter running engine, is a cleaner and more efficient running engine.

clement said:
in a performance application there is good reason for running a low temp t stat; resist preignition. not to mention some local builders that go by the name reher morrison profess this same thing. in terms of running them cold not working with eec4, i have seen .2 improvement in the 1/8 running one cold in open loop vs. running at 190*.

I do recall saying that running a lower temp T-stat at the track was a noteable exception, did I not?

clement said:
im to the point that i can give a crap if my 20 year old fox body gets good mileage, but i guess i was under the assumption we drive V8 cars for performance. perhaps i am mistaken.

You can get crap mileage with your car if you’d like, but I rather like the idea of owning a performance V8 that knocks down good fuel economy and doesn’t smell like it’s running on 7-cylinders all of the time. The argument that a car has to be poor on fuel to be considered worthy of the “performance” title is silly quite frankly. The ’13 Mustang knocks out mid/high-20s for fuel mileage, gets better emissions and makes nearly twice the power our old Fox bodies did. I added 205hp & 130lbs/ft tq to my last car and actually picked up 1-2mpg with it.

clement · Feb 21, 2013

are you saying the coolant temp is the determining factor of how hot the whole engine gets? because i can assure you the chamber temp is way over whatever the coolant temp is at any given time the engine is running. the oil temp has a lot more to do with bearing speed and rotating/reciprocating friction, how long the engine has been running and oil weight much more than coolant temp. and oil temp for what period of time will be the biggest determinant of how clean the oil stays. as far as carbon, i have engines that i have only run vp c12 in because they were power added combos. you tear them down after 300 passes and the engines look like they were just assembled. absolutely zero carbon. and those engines never ran above 130* at the finish line. due to this it is my opinion that the fuel itself has more to do with carbon than engine temp.

i took your comment about the hot lapping at the track as road racing. my mistake. ill give you that they are more fuel efficient, i did say in a car that has zero performance use. as far picking up hp, there is a difference between what the dyno says and accelleration. if you made it run hotter with a given fuel, due to chamber/piston/cylinder temps you have to pull timing in order to keep the engine from preignition. that being the case i have NEVER seen a heat soaked accellerate faster than one that was cold. i think the disjunct here is we use our cars differently. as far as your coyote comment, i dont see a lot of performance tuners making the car run HOTTER to make it run better. im sure increase in performance has nothing to do with piston speed, variable valve events, or cylinder head/induction improvements over the past 20 years.

Gearbanger 101 · Feb 21, 2013

clement said:
are you saying the coolant temp is the determining factor of how hot the whole engine gets?

No, that's not what I'm saying. I'm saying coolant temperature was a contributing factor in how the ECU performed its function and how cleanly and efficiently the engine will run and how it contributes to oil cleanliness, fuel economy, emissions, etc.

clement said:
i have engines that i have only run vp c12 in because they were power added combos. you tear them down after 300 passes and the engines look like they were just assembled. absolutely zero carbon. and those engines never ran above 130* at the finish line. due to this it is my opinion that the fuel itself has more to do with carbon than engine temp.

A race engine running C12 fuel, WOT, for 1/4 of a mile at a time is not your average street engine. Running any engine WOT for any length of time is a sure fire way to burn away carbon...never mind one that spends the majority of it's life doing it. How many times have you changed the oil and filter throughout the course of those 300-passes? I'll bet several. That's less than 100-miles in total. Hardly what I would consider comparable to a daily driven street engine, running pump gas (now blended with ethanol) on a daily basis in all weather and driving conditions for several thousand miles between changes.

As you said....we're talking different uses here. For a primarily street driven vehicle, keeping coolant temps up to and consistent with recommended levels is always most beneficial. I'm not saying run it hot....but run it a recommended operating temperatures. Running below recommended levels generally shows little benefit with several negatives I’ve already noted.

clement said:
i took your comment about the hot lapping at the track as road racing. my mistake. ill give you that they are more fuel efficient, i did say in a car that has zero performance use. as far picking up hp, there is a difference between what the dyno says and accelleration. if you made it run hotter with a given fuel, due to chamber/piston/cylinder temps you have to pull timing in order to keep the engine from preignition. that being the case i have NEVER seen a heat soaked accellerate faster than one that was cold. i think the disjunct here is we use our cars differently.

I wouldn't say stock coolant temperature levels are reserved for vehicles with zero performance use. Ever vehicle, of every variation rolling off the showroom floor over the last 25-years has maintained the same standard. Whether it's a 20-year-old 90hp Ford Escort, or a brand new 420hp Mustang GT. Pull the thermostat out and they're rated at the same 192-195F. They’re run at these levels because this is what’s required to meet EPA standards. They don’t just pull these numbers out of then air?

Heat soak, is heat soak no matter what you're running. You cool the vehicle between rounds to cool the entire engine down (primarily the intake manifold), not so much just the coolant levels. Running a track car with race gas built to run 1/4 at a time is one animal, bur in a street car...for that short time you're pulling up to the staging lanes, then blasting down the strip 1320ft, a 12-degree difference in thermostat opening temperatures isn't going to make a lick of difference in your ET''s. It’ll make more difference on the drive home that it will at any race track. At the track, It's not going to change your under hood radiant temps or the ambient air temperature any. You'll bet more benefit throwing a bag of ice on your intake manifold between rounds than you would swapping thermostats.

clement said:
as far as your coyote comment, i dont see a lot of performance tuners making the car run HOTTER to make it run better. im sure increase in performance has nothing to do with piston speed, variable valve events, or cylinder head/induction improvements over the past 20 years.

My comment about the Coyote had nothing at all to do with coolant temps...or temperature at all for that matter. I was only addressing your statement that presumed to poor mileage and high performance had to go hand in hand with one and other.

clement · Feb 21, 2013

Gearbanger 101 said:
No, that's not what I'm saying. I'm saying coolant temperature was a contributing factor in how the ECU performed its function and how cleanly and efficiently the engine will run and how it contributes to oil cleanliness, fuel economy, emissions, etc.

oil can stay clean as long as it gets to operating temp for a long enough period of time. whether you do it by driving it or using an oil heater in a dry sump, it doesnt matter. if you are dumping so much fuel in that you have contamination of the oil, you are going to wash the rings out of it. as i said before, the piston, cylinder and chamber temp get hot. the rings seal. ring seal is what keep most of the contamination out of the oil the difference in engine temp alone with a 192 vs a 160 or even 120, assuming the oil gets up to temp and the pistons have expanded enough to seal; is such a small variable its not even worth considering when it comes to oil contamination. the contamination that occurs happens before the pistons have cycled enough to reach operating temp and expand. that is why the oil temp needs to get high enough to evap it off. which will happen if you run it long enough, even if the coolant temp is down. im kind of surprised i am having to explain this to you.

A race engine running C12 fuel, WOT, for 1/4 of a mile at a time is not your average street engine. Running any engine WOT for any length of time is a sure fire way to burn away carbon...never mind one that spends the majority of it's life doing it. How many times have you changed the oil and filter throughout the course of those 300-passes? I'll bet several. That's less than 100-miles in total. Hardly what I would consider comparable to a daily driven street engine, running pump gas (now blended with ethanol) on a daily basis in all weather and driving conditions for several thousand miles between changes.

i have also run similar race engines on pump gas. pull them apart and guess what? carbon everywhere. its the fuel. considering a daily driver averaging 2000 rpm compared to an engine that runs at 7000 rpm every time it gets started; ever heard of bearing speed? which one is easier on the oil again?

As you said....we're talking different uses here. For a primarily street driven vehicle, keeping coolant temps up to and consistent with recommended levels is always most beneficial. I'm not saying run it hot....but run it a recommended operating temperatures. Running below recommended levels generally shows little benefit with several negatives I’ve already noted.

and my point is just because the coolant temp is a little low doesnt mean the oil temp is low. they are two completely different things.

I wouldn't say stock coolant temperature levels are reserved for vehicles with zero performance use. Ever vehicle, of every variation rolling off the showroom floor over the last 25-years has maintained the same standard. Whether it's a 20-year-old 90hp Ford Escort, or a brand new 420hp Mustang GT. Pull the thermostat out and they're rated at the same 192-195F. They’re run at these levels because this is what’s required to meet EPA standards. They don’t just pull these numbers out of then air?

im aware of why its done. that doesnt mean its the best thing for piston durability in a performance application.

Heat soak, is heat soak no matter what you're running. You cool the vehicle between rounds to cool the entire engine down (primarily the intake manifold), not so much just the coolant levels. Running a track car with race gas built to run 1/4 at a time is one animal, bur in a street car...for that short time you're pulling up to the staging lanes, then blasting down the strip 1320ft, a 12-degree difference in thermostat opening temperatures isn't going to make a lick of difference in your ET''s. It’ll make more difference on the drive home that it will at any race track. At the track, It's not going to change your under hood radiant temps or the ambient air temperature any. You'll bet more benefit throwing a bag of ice on your intake manifold between rounds than you would swapping thermostats.

thats an assumption. and an incorrect one. a cold longblock is faster than a hot one and ive proven that on everything from 14 second slugs to 9 second NA combos. running a 160 or a restrictor will keep them from building heat and allow them to cool faster. have you actually tried it? whatever, im tired of arguing about it.

My comment about the Coyote had nothing at all to do with coolant temps...or temperature at all for that matter. I was only addressing your statement that presumed to poor mileage and high performance had to go hand in hand with one and other.

i was commenting on fox bodies since that was the original topic. actually i just bought a 2013 coyote last weekend, a little automatic car. its sitting next to my 93 and only has a 100 miles on it and still has 87 in the tank and since i drive a toyota daily . but maybe when it gets a few more miles on it my first test with it should be the dragstrip performance difference between operating temp and dead cold. ill get back to you on that.

How cool is too cool?

SeaCorey

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How cool is too cool?

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