Cooling Fan Switch.. Why? (Page 1/1)
hunter29 JUN 08, 07:51 PM
So RD sell a switch that closes at 210*, What was GM's thinking when they decided it would be 235* ? Why let it get that hot, or is that not really that hot?
Gall757 JUN 08, 09:12 PM

quote
Originally posted by hunter29:

So RD sell a switch that closes at 210*, What was GM's thinking when they decided it would be 235* ? Why let it get that hot, or is that not really that hot?



Back in the early 80's GM was scrambling to get past the emissions testing by the EPA (I think). What they found was a hotter engine was cleaner, and passed SMOG easier. It probably helped the mileage a bit too. They really didn't want the fan on much either, because it would wear out.
theogre JUN 08, 11:44 PM
Because GM and many others knows a Engine at 220 to 235°F isn't "too hot" regardless of BS pushed by aftermarket vendors and fake "experts."

If you have AC in Fiero and some others then control head AC On force the Rad Fan and V6 engine blower On and Rad Fan Switch Does Nothing.
Many simply force Fan on w/ AC on to "fight" preheated air from AC going thru the Rad. Others cycle the fan on/off as AC clutch is on/off. Both have different advantages...

Plus many claim engine runs hot has Big problems w/ the coolant system, body panels, or both.
Examples:
Many are missing or has damage body parts to force air thru the rad and AC condenser. Fiero moving will force more air thru the rad then fan.
"Minor" bending/dents of coolant pipes hurt coolant flow way more then most think.
Many run weak or no "Antifreeze" causing rust and crap blocking rad and heater tubes etc.

Then Stant started making the SuperStat® Thermostat over 10+ years ago that "smooths out" wide temp swings that "freaks out" many owners of Fiero and other models w/ temp gauge w/ direct wired to the senders. Car has nothing wrong but Many aftermarket vendors prey on these people.
Fiero has a Larger "temp swing problem" w/ OE Tstant because Coolant system has 2 to 3 times the "water" vs FWD cars w/ same engines to heat evenly and many never "warm up" driving locally in cool or cold weather.

See my Cave, Thermostat and rest of section.

------------------
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

jscott1 JUN 08, 11:54 PM

quote
Originally posted by theogre:

Because GM and many others knows a Engine at 220 to 235°F isn't "too hot" regardless of BS pushed by aftermarket vendors and fake "experts."





I make no claims at being an expert, fake or otherwise. But I respectfully disagree. The 235°F fan set point may have been okay on new cars in the 80s in moderate climates, but there is no questions this stresses 30+ year old systems in hot climates in a way that is completely unnecessary today.

I happily run a 160°F thermostat, and with the a/c switch more or less permanently set to on, my engine runs much cooler. And yes I'm still in closed loop and yes I still get 30 mpg on the highway.
theogre JUN 09, 12:34 AM

quote
Originally posted by Gall757:
Back in the early 80's GM was scrambling to get past the emissions testing by the EPA (I think). What they found was a hotter engine was cleaner, and passed SMOG easier. It probably helped the mileage a bit too. They really didn't want the fan on much either, because it would wear out.

Sorry no.
Even before emissions rules that started in the 70's, 195°F Tstant was a very standard item. All Tstant does is set the Bottom Limit of Normal Operating Temp.
If you added a T-gauge to 50's to 70's cars then you find most run between 210 to 230°F depending on weather and more.
Very few cars and light trucks have T-gauge built into them as OE. Even one that have them, nearly none had numbers on them because is never accurate. Fiero was an "odd ball" w/ numbers but use same cheap parts to make them.

But yes, wear out of Rad Fan motor is a problem. More so when some people wired to have them on full time every time.
Is likely one reason 84 Fiero and others w/ AC has 2 speed fans... Slower RPM allows longer life and less noise.
(Other GM ECM/PCM allows 2 speed rad fans too but not wired like 87-88 Fiero L4.)