Tested the relay by pulling the temp switch harness and doing the paper clip to motor test and the fan and fan relay appear to be functioning normally. Also the fan comes on when I turn on the a.c.

What temp should turn the fan on? Only thing I have to go by is the temp gauge on the dash for reference. Not sure if ive ever heard the fan run and suspect maybe a faulty temp switch.

If I remember, theyre the same as Corvette....237*

According to the service manual, the switch turns the fan on at 235*F (113*C), and once on, only turns off below 225*F (107*C).

Edit: corrected as per Gall's post below.

[This message has been edited by Bloozberry (edited 06-14-2011).]

the service manual has as much trouble with Celsius as I do......

107

[This message has been edited by Gall757 (edited 06-13-2011).]

Bloozberry is correct

------------------
86 Fiero 2M4 Silver, and 86 GT

K TYVM all but gotta say that I get a lil freaked out when the temp gauge gets past 220. Just a Fiero noob thing I guess. Maybe a little nurotic...

Fieros run hot......but they were set up that way. The computer expects it, and if you take out the 195 degree thermostat and put in a lower one, your mileage goes down and the thing often does not run right. It is kind of strange to get out of the car after a long trip and feel all that heat pouring through the deck grilles, but that's what GM intended.

quote Originally posted by Gall757: Fieros run hot......but they were set up that way. The computer expects it, and if you take out the 195 degree thermostat and put in a lower one, your mileage goes down and the thing often does not run right. It is kind of strange to get out of the car after a long trip and feel all that heat pouring through the deck grilles, but that's what GM intended.

This is hearsay. I have a 160F thermostat in my GT and it runs just fine. I get over 30 mpg on the highway, so it's running efficiently.

I installed 210 degree temp switches on all my v-6 Fieros (got them from Rodney Dickman). They work great. I never see the temps rise close to the red zone while sitting in traffic with the A/C off. I highly recommend this option I still have the 195 degree t-stat in place so running temps remain unchanged.

Once the engine cools down you simply unscrew the original temp switch and screw in the new one. Coolant does not leak out of the hole while performing this as long as you do not remove the cap on the T-stat housing.

quote Originally posted by jscott1: This is hearsay. I have a 160F thermostat in my GT and it runs just fine. I get over 30 mpg on the highway, so it's running efficiently.

You live in Houston too. I doubt if your Fiero ever has a chance to run cool. Don't presume your conditions are like everyone else's.

quote Originally posted by Gall757: You live in Houston too. I doubt if your Fiero ever has a chance to run cool. Don't presume your conditions are like everyone else's.

I didn't presume that my experience translates to everyone else, but your blanket statement is not true.

And as warm as it gets in Houston, it's never gotten to 160F (all time high temperature is 109F). In other words the engine will run at 160F all day long here and I have none of the issues that you describe. My mileage did not go down and my engine still runs right .

This is a controversial subject I know, but I'm in the "GM made it too hot" camp.
In principle, 235F is safe.
But the first time I tested my fan switch, the gauge was getting into the red when it finally switched on, so I don't trust it much.

Even if the switch is accurate, 235F doesn't give you much leeway to find out whether the fan will successfully cool the car or if it's going to keep getting hotter. My fan is doing a fine job so far but I want some warning if the situation changes.

Also, a hotter engine == hotter engine bay electronics. Heat over time kills electronics.
On a related note, the fan switch also activates the trunk fan on cars equipped with it. This fan cools the alternator and ignition coil (I wish it cooled the ICM).

I use a 180F thermostat and use the A/C switch to turn on the fan around 220. Someday I'll get a 210F auto fan switch but right now I just switch it manually.
I know from WinALDL that my gauge is very close to the CTS reading @ 220.


I do care about the mileage, and have been tracking how it improves as I fix stuff up. But I haven't experimented with thermostats yet.
Eventually I plan to see what a 195F thermostat does to my mileage vs 180F. But that experiment will give more significant results in the winter.

My inclination however, is that unless it makes a dramatic difference then I'd rather keep things cooler. I know GM set it up for 195/235F, but then these cars are also known for heat related problems so I don't take their configuration as gospel. They had some conflicting goals to worry about, including CAFE ratings and emissions.

quote Originally posted by armos: This is a controversial subject I know, but I'm in the "GM made it too hot" camp. In principle, 235F is safe. ... My inclination however, is that unless it makes a dramatic difference then I'd rather keep things cooler. I know GM set it up for 195/235F, but then these cars are also known for heat related problems so I don't take their configuration as gospel. They had some conflicting goals to worry about, including CAFE ratings and emissions.

I agree 100% I think GM was trying to placate CAFE and set up these cars to run hot intentionally. On a 20+ year old car I'm not comfortable running it that hot as it gives you very little warning if something goes wrong. With my car at 160F I will know instantly if I have a belt slipping, or low coolant, or low flow, etc. At 235F you get no warning before things boil over.

Agreed about what GM was up to....they needed the most complete combustion they could get....

But operating temperature has nothing to do with your thermostat.... Your car runs hot no matter what thermostat you put in there....it just takes longer to get to operating temperature because you are opening the whole system at 160 instead of 195. After driving the Houston freeways for 10 minutes, your car is operating at 220 or so. Up north it might take 20 minutes....and all that time operating below 195 the combustion and mileage are not the best. In Minnesota in the dead of winter it may never get there....so GM wanted to make sure the minimum was 195. Using a lower temperature thermostat just lengthens the time taken to get the engine up to claimed efficiency.

quote Originally posted by Gall757: Agreed about what GM was up to....they needed the most complete combustion they could get.... But operating temperature has nothing to do with your thermostat.... Your car runs hot no matter what thermostat you put in there....it just takes longer to get to operating temperature because you are opening the whole system at 160 instead of 195. After driving the Houston freeways for 10 minutes, your car is operating at 220 or so. Up north it might take 20 minutes....and all that time operating below 195 the combustion and mileage are not the best. In Minnesota in the dead of winter it may never get there....so GM wanted to make sure the minimum was 195. Using a lower temperature thermostat just lengthens the time taken to get the engine up to claimed efficiency.

This is not entirely correct. The thermostat DOES set the lower setpoint for the engine temperature. My thermostat opens at 160F and since my a/c is running nearly constantly the fan is already on and the engine will stay at 160F.

If for some reason I turn off the a/c and the car isn't moving then the engine will heat up until the fan switches on.

quote Originally posted by Bloozberry: According to the service manual, the switch turns the fan on at 235*F (113*C), and once on, only turns off below 225*F (107*C). Edit: corrected as per Gall's post below.

Is there an AC override? Even if there was I can't see how that little fan is going to drag the water temperature down to 160....wishful thinking I suspect.

[This message has been edited by Gall757 (edited 06-17-2011).]

I read somewhere that the Fiero fan can simulate the flow of air @ 35 mph. Considering you are doing ~1000 rpm sitting in traffic, that's good cooling. If your system has a problem, no fan will help you out regardless.

I personally think 235F is too hot for the fan activation temperature. Keep in mind that the engine oil will be near that temperature, as well. And it's been proven that engine oil breakdown becomes progressively worse as the oil temperature goes above 200F. For this reason, I put a 210F fan switch (from Rodney Dickman) in my Fiero. And after installing a 7730 ECM (which doesn't use the fan switch), I programmed the ECM to turn on the fan at 200F.

The oiling in the 2.8 V6 is dodgy enough as is. There's no sense adding thermal breakdown to the mix.

One nice thing about a 195F thermostat and 210F fan switch is once the engine warms up, the thermostat needle basically parks itself halfway between the first and second hash marks on the gauge. Maybe it's just me, but having a steady coolant temperature gives me more peace of mind. It's probably better for the engine, too.

quote Originally posted by jscott1: This is hearsay. I have a 160F thermostat in my GT and it runs just fine. I get over 30 mpg on the highway, so it's running efficiently.

Im totally with you on that. I have 160* stats in almost all my cars including both the Corvettes and the Super Bee. It has no effect I can tell on anything except the engine stays cooler. Everything in the engine bay also stays cooler like battery, alt, hoses and wiring............. The only ones I havent changed are just too much of a pita to get to for me to bother with. It massively helped my turboed Fiero with performance. It ran crappy with 185*, and barely run at all with the OEM. Ran perfectly with 160* and a 175* fan switch. My fan barely ever kicked on except in bumper to bumper traffic on a 95* day.

quote Originally posted by jscott1: On a 20+ year old car I'm not comfortable running it that hot as it gives you very little warning if something goes wrong.

At 235*F, if something goes wrong you still have a margin of 30*F before the light comes on at 265*F. Albeit at 265*F the pressure cap on the rad will blow shortly thereafter. I guess we have it luckier here in the cooler climes and less traffic. My car's temp rarely gets to midscale using all OEM spec parts (thermostat, switch, etc.), let alone getting to the point of turning on the rad fan.

quote Originally posted by weloveour86se: K TYVM all but gotta say that I get a lil freaked out when the temp gauge gets past 220. Just a Fiero noob thing I guess. Maybe a little nurotic...

That's normal. I just thought I'd add that a lot of gauges are way off to begin with from pegging gauges at startup. Even if the wiring was fixed, not everyone goes to the trouble of re-calibrating the gauge afterward using proper resistors

quote Originally posted by Gall757: Is there an AC override?

If you turn on the AC, the fan will come on (assuming everything is working properly), OR if the AC pressure switch on the compressor reaches 280 psi it will tun on the fan, according to the 88 service manual. The way it is wired, it will happen even if the AC is off, so you could test either switch's wiring by grounding the wire at them.

IMO, 235 is too hot, I would use a lower temp fan switch (easiest would be for the 89 Turbo Trans Am or 86-87 Regal Grand National), and the stock 195 degree thermostat

I have a little lower of a thermostat like 180, and the 7730 conversion turns on my fan at 200 or 210. If I am driving my temp never goes above the thermostat temp. My temp gauge is accurate to my thermostat, and the fan turning on at it's tempeture. Only time my fan comes on is when it's not moving, never comes while driving. I drove it on 90 degree days and the same thing. I still get 27-28 mpg in country driving. if you are worried about the winter just switch thermostats, it takes like 1 minute. 235 degrees is unnecessarilly hot IMO.

quote Originally posted by Gall757: Is there an AC override? Even if there was I can't see how that little fan is going to drag the water temperature down to 160....wishful thinking I suspect.

Trust me the fan will cool it to 160F all day long, and yes the fan runs anytime the a/c is selected. Note that the a/c doesn't even have to work the HVAC switch will turn on the fan regardless.

Sorry to open this post again but I have a question about the temperature in my 88 GT.

I initially searched for this post because I wanted to know what temp my fan should come on. So, idling the car and watching the gauge - the temperature creeps up to 235 and voila, the fan comes on. After a very short while the temperature drops to about 225 and it goes off so I am assuming my temperature gauge is fairy accurate,

So can someone give me some pointers as to why when driving around she sits at a constant 150 with no AC or fans running inside?

The car has just had a full coolant flush as well but no difference and I have a 195 thermostat in her which is just over 1000 miles old.

Many thanks

quote So can someone give me some pointers as to why when driving around she sits at a constant 150 with no AC or fans running inside?

an88_fierodiva

150 deg F is quite cool--too cool for proper engine operation.
I would check to see if the needle on your gage has moved. During "bulb test" (unless the fix has been performed) the temp gage needle bangs the stop on the far right, and it is not uncommon at all for that constant impact with the stop peg to force the needle to move back (clockwise) on it's shaft, giving an erroneous and cooler reading at all actual temperatures.

[This message has been edited by maryjane (edited 12-10-2011).]

Thanks for your response which is an interesting idea however the fan switch on temp is exactly 235 on the gauge and the fan off temp is 225 on the gauge so this must mean that the needle has not slipped? Perhaps a faulty thermostat?

The other thing to look at is a stuck thermostat. New parts can be bad....so just pull it out and see if it looks right. If you want you can boil it on the stove to find out when it opens.......

The ONLY thing that regulates the temperature of the engine is the thermostat.

If your temp gauge is working correctly, then your thermostat is not.

quote Originally posted by an88_fierodiva: So can someone give me some pointers as to why when driving around she sits at a constant 150 with no AC or fans running inside?

Sounds like you might have the problem I reported here... Check your thermostat !

If so, spend a couple extra dollars and get this superior 195º thermostat - Stant SuperStat 45819.

Thanks but I pulled the stat out today when doing the coolant change and it's fine with no bends etc

Might have to order a new one but shipping costs to the Uk seem to have almost doubled

Checked on rockauto.com and their quote for the part is approx $6 and shipping is $25 lolol

Can probably pick one up here but will probably be jap made

quote Originally posted by Patrick: Sounds like you might have the problem I reported here... Check your thermostat ! If so, spend a couple extra dollars and get this superior 195º thermostat - Stant SuperStat 45819.

Napa has it here for $14.95 their part number is #552095. Going to pick it up today then toss it in when things cool off. TYVM Patrick +4u!

I wish I had a napa close by

quote Originally posted by an88_fierodiva: I wish I had a napa close by

More then happy to send you this one at cost and shipping if it's any cheaper. Or I could just run and get another. You could probably get it quicker and cheaper tho, dunno. If I can help just let me know.

First thing I checked was for the made in USA before I even paid and it's there.

The Fiero goes into closed loop operation between 125° and 150° according to Rodney Dickman's site.
I would consider 150° to be too low since it's right on the edge of that window. There's nothing wrong with the stock Fiero fan temp coming on at 235°F. But we are talking about 23+ year old cars now, and while it was fine for a new Fiero, I prefer to lower the temp a bit just to ease down the pressure on the cooling system. I use a 180° t-stat and Rodney''s 195/185 fan switch. My temps never go above about 200° under any circumstances and I still have normal drive-ability and enough heat in winter to run you out of the car.

quote Originally posted by weloveour86se: More then happy to send you this one at cost and shipping if it's any cheaper. Or I could just run and get another. You could probably get it quicker and cheaper tho, dunno. If I can help just let me know. First thing I checked was for the made in USA before I even paid and it's there.

Thank you so much - I will find out from our supplier here in the UK how much tomorrow and will come back to you

[This message has been edited by an88_fierodiva (edited 12-12-2011).]

I have managed to get a Stant thermostat from our supplier here in the UK for 16 gbp (approx 24 USD) including shipping.

Thanks for your offer though.

Many thanks.

quote Originally posted by an88_fierodiva: I have managed to get a Stant thermostat from our supplier here in the UK for 16 gbp (approx 24 USD) including shipping.

... $24

I'm hoping it's the SuperStat you're getting (especially for that price!), as Stant also sells regular crappy thermostats.

I'm not sure which one it is but it's the only place that sell them here and there was no choice either.

I shall let you know what it is when it arrives - should be here tomm.

quote Originally posted by an88_fierodiva: I'm not sure which one it is...

That's why I posted the part number to get, as the regular Stant thermostat is probably just another made in China piece of garbage. Oh well, cross your fingers.

quote Originally posted by Patrick: ...get this superior 195º thermostat - Stant SuperStat 45819.