For those of you who have replaced their radiator cooling fan motors. Does the new motor draw less amperage than the 32 year old original? My orig. fan works fine, but when it turns on, it drags the engine down until the idle control brings the RPM's back up. Seems excessive.

Also tho, if I turn the blinker on when the engine is idling, the RPM's hunt around as the alternator compensates for the on/off load. Normal?

Mine does not do that, I would check for a short in the wiring, also check the voltage when the motor kicks on.

My 86SE and 87GT RPM drops when the fan comes on. The 86 is more noticeable and it has a motor thats only a couple of years old. Both my cars volt meter wiggles just a little when idling and the turn signals are activated.

quote Originally posted by fierofool: My 86SE and 87GT RPM drops when the fan comes on. The 86 is more noticeable and it has a motor thats only a couple of years old. Both my cars volt meter wiggles just a little when idling and the turn signals are activated.

But when the fan turns on, does the engine almost drop to a stall before the idle control kicks it back up? I can understand the gauge moving due to the load, but mine is the engine surging in between flashes.

[This message has been edited by donuteater306 (edited 07-15-2019).]

Yes, the 86 does. It isn't a short but probably due to bad grounds and connections. The 86 has had a rough life. The engine doesn't surge with flashes, though.

[This message has been edited by fierofool (edited 07-15-2019).]

Thanks for the replies. I'm going to go through the grounds, clean all the contacts and most likely replace the fan motor...just because. When I turn on my AC, the engine almost comes to a halt before the idle control picks it back up, then it's perfectly smooth. I know that with the instant electrical load on the alternator from the compressor, cooling fan, and blower motor all turning on at once...it makes sense. However, when I turn on just the defrost, the compressor turns on like normal but there's no real load on the engine. Just when the cooling fan turns on.

My next question is...

Is the Four Seasons fan motor the best, most reliable option?

I think the Four Seasons motor was what I bought. GTRS of the Georgia Fiero Club just installed this. He says it draws fewer amps and moves more air.

Any iffy wiring can and often will make big problems.
See my Cave, Electric Motors as just 1 example.

Motors can be "bad" but is often cause by iffy wiring or worse make iffy wiring worse.

Is why many recommend Replacing Battery Cables when the Starter dies. Iffy cables may look ok to you but have high resistance causing low volts when starter runs. You Cannot test this using standard DVM on Ω setting. Might test for Voltage Drop or DC Amp Clamp but starter often have no time to test and worse most can't understand starting current vs running current and get false results. Time matters because Most meters don't update the screen fast enough to read impulse loads like stater or HL motors.

Go thru the whole car to fix/clean all ground. See my Cave, Wire Service have many but not all in the ground list but can give you a start.
Next is buy/borrow DC amp clamp or maybe Starter/Alt amp "meter" to read Amps w/o cutting wires. (these "Vintage Meters" just uses magnets to read field flow over alt and other big draws. I mainly find them on Ebay etc.) Most fan/blower motors only draw 7-14a w/ engine running.
Most amp clamps are AC Only and useless here.

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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

Every Fiero I have ever owned did this, including my current, low mileage 86.

RPMs drop when fan kicks on, then car catches it and returns it to normal. I don't know that I'd say it is "near stall" conditions, but it is noticeable.

I had the same issues as mentioned above with my 2.8. I checked all grounds, etc,.... with not much change. I then upgraded to the CS-130 Conversion. Works on the 85 to 87 2.8's. I think it's 105 amps. What a difference. hardly any lag when fan comes on, signals don't slow down when other loads kick in.
No dimming of headlights when a/c is engaged at idle.
There use to be a link in Orges Cave on this.. will see if I can find it,, hold on...........................................

Might be in here.. http://fierocave.shorturl.com/ If not search CS-130 conversion.

Here's another... https://www.fiero.nl/forum/Forum9/HTML/000035.html

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

[This message has been edited by Spoon (edited 07-16-2019).]

Yup SI alts make less amps vs CS-130 at same speed and engine loads. Even w/ Aftermarket mods to make more amps SI Loses to CS w/ similar peak amps.

See my Cave, CS Alternator and Rabid-Wombat's CS-130 Conversion for 85-87 V6.
L4 might need different PN if mounting ears are different.

You still need to fix/clean all grounds at minimum.
Iffy Alt and Battery cables won't help and most have them.

Wow thank you all for the replies and suggestions. A friend has a DC amp clamp so we're going to check the motor on Saturday. If all is good with the motor (I don't expect it to be at 32 years and 265k miles) I will then check all the grounds and connections. If all checks out OK, time for the CS conversion! Prob going to do the conversion anyway because, why not

Thanks Ogre for the Cave!