I live near Charlotte NC. Just bought a 1986 Fiero GT. Was thinking about swapping out the thermostat from 195 to 180 degree. Any thoughts no switching out to a lower thermostat in a hotter region?
The Pontiac engineers designed the engine in your Fiero to run the most efficiently with a 195° thermostat.
A lot of us feel more comfortable with the cooling fan coming on at a lower temperature than the factory setting of 235°. Therefore, the installation of Rodney Dickman's 210° on and 200° off fan switch makes a lot of sense.
Originally posted by Patrick: The Pontiac engineers designed the engine in your Fiero to run the most efficiently with a 195° thermostat.
A lot of us feel more comfortable with the cooling fan coming on at a lower temperature than the factory setting of 235°. Therefore, the installation of Rodney Dickman's 210° on and 200° off fan switch makes a lot of sense.
True for 195° T-stat... Even if have 185° often does nothing but make no heat for the Cabin in cold weather.
But 210° switch can & often Will keep the Rad Fan On all the time and often That Fails soon. Fiero AC wiring also keep fan On and often dies too. Rad Fan, and V6 engine blower, were not made to be On full time same as most other including current models.
RD sold this "fix" a lot because Most have No Clue how the coolant system works or that the Engine Do Not Care about running @ 220 to 230° but "Everyone" said it's "Running Hot." Worse, Many to Most bought that or have rewired fan circuit are people w/ major cooling system problems and make the fan On hinds the problem until so bad even that won't work. "Running Hot" way often means have Rad &or H-core full of crap in/on/both, bent pipes under the car, Fiero V6 w/ plastic WP (and often that problem is a side effect of other problems), and more.
87+ Dukes w/ ECM control rad fan Turn On @ ~ 220° and never turns On unless stuck in very slow traffic and related situations even when weather is Hot, 90-100° true temp. Most time between 200-210° and I've replace the Rad and H-core and fix other coolant problems.
------------------ 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)
Originally posted by Patrick: The Pontiac engineers designed the engine in your Fiero to run the most efficiently with a 195° thermostat.
I think the stock V6 works better at 195°F than 180°F, but I don't think it's anything the Chevrolet engineers (the V6 is a Chevrolet engine) did in particular.
I think it's just the evaporation of gasoline in the intake air that works better with the higher coolant temperature; the design staff didn't get to choose the fuel. They had to make the engine work with readily available pump gasoline.
I’m not buying it, the higher temps were for emissions…not to make the motor run better. The only place you want heat is in the exhaust to help with flow. Fuel only needs to be heated to about 110 deg to properly vaporize. Too much vaporization is not a good thing. If someone can send me a technical paper on why higher temps are better I’d be more than happy to change my mind. I’ve always had sbc 350’s and they always ran better at 180. Currently the one I have hated 195…would climb to 220 in the summer. Changed to a 170 thermostat….runs at 180-185 constantly now. It has a bit of a cam in it, radiator is a 4 row, new water pump. Absolutely loves it. So….flame on !
I've always maintained that a 180* thermostat was better for engine life. Get stuck in traffic with the 195* thermostat and coolant temperatures can soar. On a hot day with the A/C on even overheating may occur. Fieros were also designed to take in cool outside air to the intake because it is beneficial. On modified or boosted engines the 180* stat is important as less heat = additional detonation protection and ability to generate more horsepower.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
But 210° switch can & often Will keep the Rad Fan On all the time and often That Fails soon. Fiero AC wiring also keep fan On and often dies too. Rad Fan, and V6 engine blower, were not made to be On full time same as most other including current models.
RD sold this "fix" a lot because Most have No Clue how the coolant system works or that the Engine Do Not Care about running @ 220 to 230° but "Everyone" said it's "Running Hot."
Im going to disagree with one aspect of what Orge said. Be warned everything else he mentioned I believe to be 100 percent accurate, especially that people rewire their fan circuit to mask unlying issues.
However, I am an electrical engineer by trade and have a good understanding of the motors that are used in the blower and cooling fan. Running them all the time will not induce significant premature failure. There is a common misconception among old-school car mechanics that the fan running longer reduces the fan's lifetime and it's simply untrue. What actually kills the motors is when you increase the amount of time it cycles in operation (stop-start). A fan that comes on once and stays on the entire time the car is running is going to last longer than a fan that starts and stops 5-6 times. Peak current is what harms fan motors the most, which is what is experienced when you dump 12v on a stopped fan.
Whether or not a 210 thermostat will cause more cycling or not I cant tell you. But running a fan longer wont hurt it as long as you arent cycling it more!
To me it depends on a lot of factors for each owner to decide.
Back in the day, many used 180-degrees thermostats on carbureted vehicles before computer-controlled systems.
But now, bare stock fuel injection vehicles with the original 195-degree thermostat would be the best choice (IMHO) because they're programmed to run hotter; better mileage, boil out moisture from the engine oil, etc.
Most auto stores carry 195-degree thermostats and finding a 180-degrees thermostat for the Fiero may be harder. To me, deviating away from the factory thermostat on computer-controlled engines may cause drivability and other problems later.
If the vehicle sees a lot of slow traffic AND the coolant temperatures are often high, first follow theogre and made SURE that the coolant system is running properly. THEN it makes sense to replace the GM 3040674 Radiator Fan Switch to get the fan started sooner than the stock switch; don't 'mask' the problem.
Of course, a modified engine is a different animal!
And as a postscript - I agree with Dukesterpro statement by "running them (fan motors) all the time will not induce significant premature failure" and cycling (start and stop) kills electric motors.
But now, bare stock fuel injection vehicles with the original 195-degree thermostat would be the best choice (IMHO) because they're programmed to run hotter; better mileage, boil out moisture from the engine oil, etc. Of course, a modified engine is a different animal! And as a postscript - I agree with Dukesterpro statement by "running them (fan motors) all the time will not induce significant premature failure" and cycling (start and stop) kills electric motors.
Modern day ECM/PCM controlled engines take all engine inputs to adjust the fueling like the ETC or coolant temperature sensors inputs. The adjustment in fueling will be made accordingly. but at 180* the engine may run a bit richer and use more timing advance through the RPM range. As for the radiator fan; mine runs nearly all the time and hasn't burned out. The bottom line is that most will use the thermostat that they are comfortable with
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I've always maintained that a 180* thermostat was better for engine life. Get stuck in traffic with the 195* thermostat and coolant temperatures can soar. On a hot day with the A/C on even overheating may occur. Fieros were also designed to take in cool outside air to the intake because it is beneficial. On modified or boosted engines the 180* stat is important as less heat = additional detonation protection and ability to generate more horsepower.
I can't agree with your assessment that a 15 degree difference in thermostat rating will have an effect on engine life.
A 195 does not give you much room before things go too hot. If you want your engine to run at 200+…have at it. I still maintain that the higher temps were for emissions only. If you think 170 deg coolant won’t heat your car then why do boiler systems that heat up entire buildings at 180deg running thru hundreds of feet of pipe work ? I’m with Dennis on this..
Originally posted by Dukesterpro: Im going to disagree with one aspect of what Orge said. Be warned everything else he mentioned I believe to be 100 percent accurate, especially that people rewire their fan circuit to mask unlying issues.
However, I am an electrical engineer by trade and have a good understanding of the motors that are used in the blower and cooling fan. Running them all the time will not induce significant premature failure. There is a common misconception among old-school car mechanics that the fan running longer reduces the fan's lifetime and it's simply untrue. What actually kills the motors is when you increase the amount of time it cycles in operation (stop-start). A fan that comes on once and stays on the entire time the car is running is going to last longer than a fan that starts and stops 5-6 times. Peak current is what harms fan motors the most, which is what is experienced when you dump 12v on a stopped fan.
Whether or not a 210 thermostat will cause more cycling or not I cant tell you. But running a fan longer wont hurt it as long as you arent cycling it more!
Running rad fan and other motors a lot often "Violates" Duty Cycle of that part and Power cycling is just a part of a Duty Cycle Spec.
The majority of "Fan" Failures for vehicles and other things are not Electrical problems even for Brush motors. Car Rad Fan, heater blower, and others are make "Cheap" w/ mostly Oiled Bronze/Brass Bearing than causes a lot of failures. 120-240vac (depending where you live) home fans, vac cleaners and more often dies because bearing have bound up then the motor heats up and when ignored fries 1 time thermal fuse buried in the motors.
Some Rad Fan motors are 2 speeds and run at lower speed most times and they last longer but often fail for bad bearings. Most PC case and CPU fans run lower speeds too and still have same problem w/ bearings & those are Brush-less units.
Yes Can have low volts cause by anything in a car making any motor to draw more amp so something cooks, wear out bushes for various reasons, and other issues but most times is "bad" bearings as root cause.
It one hundred percent violates the specified duty cycle of the fan motor. However, I will say it won't make a noticeable difference in a good-quality fan's life. The duty cycle is typically established to only fit the need that it will fulfill in the car and not what the device is actually capable of doing.
The point you made about cheap Chinese bearings and bushing is correct though.
But my point still stands increasing the cycling of the fan will be far more harmful than continuously running it
3/4 months out of the year we are high 80’s to mid 90’s. Living in a higher populated area there’s a lot more stop and go traffic. Given temps and driving conditions thinking 180 degrees may be best. I’m afraid temps could quickly get to high.
[This message has been edited by MasterBaker (edited 08-10-2023).]
I am in a different situation now with an aftermarket ecu but for the last 28 years I ran stock ecu with a FS stage 2 chip and the recommended 160 thermostat and 165 fan TS. It ran flawlessly for the 28 years and Performance was great in all seasons. With my new ecu I had to bump it up to 180 thermostat and 190 on the fan. I also had to upgrade my rad to a 3 core aluminum and delete my ac as the new version of my engine produces much more heat than the original 2.8. I believe each owner will have to adjust their cooling system to accommodate the upgrades they may have made to their engines !!! sleek
Originally posted by Dukesterpro: The point you made about ❓cheap Chinese❓ bearings and bushing is correct though.
I did not say that because The Chinese had little to do with these motors.
When GM and others made car parts they used same Oil Bronze bearings for the US made motors and had same problems. GM E-motors for Fiero and thousands more was built by GM (Maybe Packard Division like many other E-parts.) or 1 of the US Contractors.
I've replace Many 60's to 80's fan/blower and wiper motors in GM Ford AMC and Chrysler vehicles w/ same type motors w/ same "cheap" bearings build way before moved/sold most manufacturing to Mexico China and worse countries. Nearly all had "bad" bearings.
I can't agree with your assessment that a 15 degree difference in thermostat rating will have an effect on engine life.
While I have no proof that higher heat levels can decrease an engines life and will not challenge your comment; lower temps should help decrease the chance of detonation on a modified engine. I believe higher temps can decrease the life of an automatic transmission. I run the 4T65eHD and the 180* Stat keeps the coolant cooler should add efficiency to the integral transmission cooler on the radiator.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I’m not buying it, the higher temps were for emissions…not to make the motor run better. The only place you want heat is in the exhaust to help with flow. Fuel only needs to be heated to about 110 deg to properly vaporize. Too much vaporization is not a good thing. If someone can send me a technical paper on why higher temps are better I’d be more than happy to change my mind.
I have tried both 180 °F and 195 °F thermostats on V6 Fiero engines. I like the 195 °F thermostat more. I am not building my Fiero to meet any emissions test.
At the higher coolant temperature, the engine needs less acceleration enrichment, and the throttle response is a bit better.
This is the warmup enrichment table I tuned on my stock-ish V6 Fiero. It is a multiplier that enriches the mixture as a function of coolant temperature: (coolant temperature axis is in °C)
Most of the extra fuel added by this table ends up unburned, because of poor vaporisation. This table exists to compensate for poor fuel vaporisation at low coolant temperatures.
Every single time I take the car, as it warms up, it passes through 180 °F, and while it drives okay at that temperature, I like it better when it reaches 195 °F.
It is hard for me (or for many others) to discuss fuel temperature, since fuel temperature is often not measured/recorded. It is however easy to discuss coolant temperature, and by proxy, the temperature of the internal surfaces of the intake ports / runners. Where did you pull 110 °F from? Warmup enrichment on my Fiero continues well beyond that, as you can see in the picture.
How is too much vaporisation a bad thing? Fuel that passes through the combustion chamber unburned is wasted and does not have any benefit that I can see.
[This message has been edited by pmbrunelle (edited 08-12-2023).]
Originally posted my question over concerns of overheating. But what failed to ask is, does 1986 2.8L Fiero have overheating issues? I was under the impression they do. With living in the southeast was concerned. Is this something to be concerned over or am I over thinking this?
Originally posted my question over concerns of overheating. But what failed to ask is, does 1986 2.8L Fiero have overheating issues? I was under the impression they do. With living in the southeast was concerned. Is this something to be concerned over or am I over thinking this?
You probably are overthinking it. I have had my Fiero in NC for over 15 years and my wife has had her's for over 10 and while mine is no longer a 2.8, neither of us ever had overheating problems on stock t-stat with a properly functioning cooling system.
The 110deg was from a book….don’t remember which one….might have been Smokey Yunick. The air cleaners on older small blocks had the flap in the snorkel that was closed when cold…..opened when 110 was reached. Get things too hot and you get vapor lock. Trying to understand , I’m old school carb guy, when the weather is cooler out my car runs much better, when it’s hotter not quite as good. So if warmer temps were indeed better then why not preheat the fuel somehow ? Or build a shroud around exhaust manifolds and draw the air past it before it reaches the intake ? Help me out here..
You probably are overthinking it. I have had my Fiero in NC for over 15 years and my wife has had her's for over 10 and while mine is no longer a 2.8, neither of us ever had overheating problems on stock t-stat with a properly functioning cooling system.
True, I don't live in Death Valley, but my rad fan rarely comes on with my 210° switch.
