So today I found out the hard way that my Radiator fan switch was broken. Having coolant spray from the top of the reservoir sure isn't fun...
But that got me thinking and looking into cooling systems a bit more. I already ordered a 212* fan switch, and after viewing some other topics, I've come to the conclusion that that was probably a good choice. However, I do have in the car a 180* thermostat. And now after looking through this site a bit more, I'm starting to question my decision on that. I know people say "the ECM still thinks the engine is cold" and "It reduces fuel economy". But my question is: How much? Is it really a big deal? My car (1985 4 cylinder) takes around 3 minutes to warm up and idles nicely between 700 and 800 RPM. I always forget to keep an eye on the temp gauge, so I don't know what the actual coolant temp was, but 700-800 RPM sure sounds like a realistic warm idle for a little 4 cylinder to me.
So my question: If my car is warming up fine and running fine with a 180 degree thermostat, will I notice any significant dips in efficiency? Or rather, would the engine still run as if it were cold and run too rich, Giving me bigger problems than fuel economy?
Basically, am I okay with this 180 degree thermostat, or should I order myself a 195* one? I'd rather not have to buy another one, but at the same time, I'd much rather spend a few bucks than damage my engine. And if the fuel efficiency thing is true, it may be cheaper in the long run, right?
Any advice on this would be greatly appreciated.
[This message has been edited by I_N_J (edited 11-15-2015).]
What I'm trying to ask isn't so much "which one" as much as "how much difference is there". I guess I should've made that clearer. I know people are gonna come in here and say 195 all day. I'm just trying to understand how much of a difference there is.
I mean, I've seen all these topics saying that the 195 is superior, and that lower ones can cause all sorts of issues, but my car runs very nicely and doesn't seem to have any trouble heating up and/or staying there with a 180 thermostat in.
What I'm really trying to figure out is if there's really much of a difference, or if there are just a bunch of people parroting all this 195 stuff. Because like I said, I can find people saying 195 all day, and I can find people saying I'll have fuel efficiency issues all day, but I can't seem to find anybody who's actually done it and can accurately give me an idea of what kind of differences I'll experience with a 180 as opposed to a 195.
...but I can't seem to find anybody who's actually done it and can accurately give me an idea of what kind of differences I'll experience with a 180 as opposed to a 195.
Well, for the price of a thermostat (not a lot of money)... YOU can be the guy who'll quantify the differences!
People regularly make mileage claims based on short-term data collection, frequently of dubious accuracy. There can be a significant difference between tankfuls from different pumps. The only way to ensure you're replacing the gas you used is to fill the tank to the top of the filler neck each time. That in itself is frowned on by many, but is the only way to ensure your calculation is accurate. An average over several tankfuls is helpful for accuracy.
I've kept a running tally since I bought my '84 SE 4 speed new. The last fill-up was at 370,627 kilometers & 32,122.5 litres. That's 8.6L per 100 km during the last 31+ years of weather, with a variety of usage patterns over the years as well. Or, 230,297 miles & 8498 US gals for 27 MPG. 7066 imperial gals gives 32.6 MPG. I've also run different thermostats, but never tracked the mileage versus any particular thermostat.
ANYway, lol, to make a long dissertation short(er) I think if you want to have accurate data, you'll have to accumulate it yourself. I predict that if you are careful to collect accurate data during a period of similar weather and similar car usage over several tankfuls at least, you'll find no detectable difference in fuel economy.
[This message has been edited by David Hambleton (edited 11-15-2015).]
Originally posted by I_N_J: But that got me thinking and looking into cooling systems a bit more. You believe several myths... Normal Engine Temp Should Be 200-220ยฐF and ECM is programed for this. Gives best MPG and lowers emissions.
But that got me thinking and looking into cooling systems a bit more. I already ordered a 212* fan switch, and after viewing some other topics, I've come to the conclusion that that was probably a good choice. Not really. 220ยฐF is better. GM even program ECM 87+ L4 using 221ยฐ Turn on sooner but stay off for most driving. (w/o AC on... AC control turn on the rad fan.)
Engine running hot then you have problem. Crush pipes, bad rad and likely other things block coolant flow. "old design" Tstat would won't help... Is why Patrick said: Spend a couple extra dollars and get this superior 195ยบ thermostat - Stant SuperStat 45819.
However, I do have in the car a 180* thermostat. And now after looking through this site a bit more, I'm starting to question my decision on that. <snip> Basically, am I okay with this 180 degree thermostat, or should I order myself a 195* one? Any advice on this would be greatly appreciated. 180ยฐ vs 195ยฐ can slow warmup time all the time. Worse in cold/freezing weather. slow warmup time can hurt MPG. Can lower heat to cabin too.
180ยฐ helps some owners driving in Warm to Hot weather most of time. Engine temp still runs in 200-220ยฐ range.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
The ECM programming does take coolant temperature into account when calculating how much fuel to inject. Also, the coolant needs to reach a certain minimum temperature in order for the ECM to go into closed-loop mode. So yes, a colder thermostat can reduce fuel economy. The question is how much. I know from personal experience that using a 160°F thermostat can noticeably affect fuel economy. But I haven't done any testing on a 180°F thermostat.
So what exactly does it mean to be in "Closed loop operation"? Is that just when it gets fully warmed up? Because my car warms up just fine in about 3 minutes.
Originally posted by I_N_J: 200-220? I was reading around elsewhere and most were saying 190-215. That's why I got the 212* switch.
I guess I'll see how well the car warms up this winter with the 180 degree stat. And if it has trouble, I'll go ahead and grab a 195.
Many people here and internet will repeat same BS don't make data true. Worse, Many Vendors sell parts to "fix" the "problems." Even push "White Papers" saying so and people believe them. If you see White Paper think TV Infomercial at best. Maybe a few facts but allot of .
"Close Loop?" Nutshell... Close loop = O2 sensor is hot and maybe other things too. Then ECM will generate best MPG etc for that engine.
quote
Originally posted by Blacktree: The ECM programming does take coolant temperature into account when calculating how much fuel to inject. Also, the coolant needs to reach a certain minimum temperature in order for the ECM to go into closed-loop mode. So yes, a colder thermostat can reduce fuel economy. The question is how much. I know from personal experience that using a 160ยฐF thermostat can noticeably affect fuel economy. But I haven't done any testing on a 180ยฐF thermostat.
Many close loop are program when O2 warm enough to generate output volts alone. On 87+ Vin R L4 coolant temp means nothing for open/close loop. I've seen close loop in 45-90 seconds after start and engine is still cold.
[This message has been edited by theogre (edited 11-16-2015).]
To see if your ECM is in open or closed loop mode you'll need to use a scanner, or a computer with an adapter cable and the appropriate software. But honestly, I doubt that will be an issue for you. If the engine warms up quickly, doesn't run too rich, etc then it should be fine. Still, being able to "talk" with your car's ECM can be a useful tool.
You have to watch ECM data to know for sure, but knowing the specs of the ECM and the exact reading of the coolant temperature sensor will tell you with a fair degree of accuracy. I don't know what the closed loop spec on the ECM is, but I'm sure someone here does.
The thermostat's job is to set minimum temp of the engine. When it's closed, coolant circulates within the engine only allowing it to warm up relatively quickly. Once the thermostat is open, coolant begins circulating through the radiator to bleed off heat. Maximum temperature is then controlled by airflow across the radiator. Specific formulas dictate the size of the radiator versus primarily the output of the engine (given x hp produces y heat in a common internal combustion engine). In situations when there is no airflow from movement, the fan switch controls a maximum temperature the engine is allowed to hit.
Contrary to what a lot of folks believe, thermostats don't just pop open and closed. They open gradually, over around 10 or 15 degrees. This allows coolant to slowly start circulating through the radiator and continue a gradual temperature change. A 180 degree thermostat will not be fully open until 190 or 195 degrees. A 195 degree thermostat won't be fully open until 205 or 210 degrees. There are plenty of videos on youtube of thermostats working if you'd like to see one in operation.
Most fan switches have different on and off temps to prevent constant cycling of the fan. A fan might turn on at X degrees and back off at X-5 degrees. Because of the way the thermostat works, you want your fan switch and your thermostat to be separated by at least 20 degrees to avoid them trampling all over each other. If your 195 degree thermostat doesn't open until 210 degrees and your fan switch comes on at 210 degrees and cools to 205 degrees, your fan switch is going to cause your thermostat to start closing *all the time*. It's unnecessary wear on the thermostat and cooling system in general. You want to be sure your fan switch will not cause the thermostat to close.
Properly diluted and pressurized coolant is good to about 260 degrees. After that, it'll boil. Manufacturers typically leave a 20 degree safety margin to allow for improperly balanced or weak cooling systems, so maximum engine temperatures are typically in the 240 degree range. Higher engine temps can also increase the likelihood of detonation (knock) and can accelerate wear on gaskets, hoses, and seals. On aluminum or mixed-material engines (eg iron block with aluminum head) engines there are some expansion characteristics which need to be managed, and carbureted engines have fuel issues that must be managed, but fuel injected iron block/iron head motors like all stock Fiero motors are totally fine up to 240 degrees.
Typically speaking, combustion is most efficient at higher temps. That's why you'll find all these older motors are designed to run between 210 and 220 - it reduces most emissions and improves fuel economy. There are some exceptions - the turbo Buicks for example run cooler to prevent detonation, which is important when intake charge temps can spike over 200 degrees. Not a problem on naturally aspirated motors.
So, to directly answer your question: Running a 180 degree thermostat won't hurt anything in an absolute sense but it won't help anything either. All running a cold thermostat will do is make the engine take longer to warm up because you'll start cycling coolant through the radiator sooner. The engine will still ultimately run at the same temperature because that temperature is defined primarily by the size of the radiator and limited by the fan switch. Always running the engine cold, such as by increasing the size of the radiator or lowering the temperature of the fan switch, will have no practical benefit and may reduce fuel economy and improve emissions. Unless you have something *specific* you're trying to do, such as control heat generated by more power or optimize for a truly unusual operating environment, screwing with the engine's operating temperature range is pretty much a pointless endeavor. There is just no reason to do it.
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