PFF - Pennock's Fiero Forum, PDA Edition

180 or 195 Thermostat (Page 1/3)

MasterBaker

AUG 09, 09:03 PM

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?

Patrick

AUG 09, 09:35 PM

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.

theogre

AUG 09, 10:59 PM

quote

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.

See https://web.archive.org/web...cast.net/~fierocave/ coolant section.
Also Stant is Gone http://www.fiero.nl/forum/Forum2/HTML/146523.html and Stant Fiero Part Numbers http://www.fiero.nl/forum/Forum2/HTML/147005.html

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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 Ogre's Fiero Cave

[This message has been edited by theogre (edited 08-09-2023).]

Patrick

AUG 09, 11:30 PM

quote

Originally posted by theogre:

But 210° switch can & often Will keep the Rad Fan On all the time and often That Fails soon.

Fear mongering.

True, I don't live in Death Valley, but my rad fan rarely comes on with my 210° switch.

quote

Originally posted by theogre:

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°...

"Most"? Maybe, but not all. At least you didn't call us all morons.

pmbrunelle

AUG 10, 12:53 AM

quote

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.

PhatMax

AUG 10, 06:43 AM

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 !

Dennis LaGrua

AUG 10, 07:19 AM

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.

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" 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 "

Dukesterpro

AUG 10, 09:40 AM

quote

[b]

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!

Vintage-Nut

AUG 10, 11:58 AM

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.

Dennis LaGrua

AUG 10, 12:22 PM

quote

Originally posted by Vintage-Nut:

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