G.T. Fieros

My 84 made it through its 32nd season like a champ. After a couple of years of lost interest where I might have only driven the car once or twice, this year my interest was a lot keener and I ended up driving the car pretty much every weekend. A makeover of the stereo system was probably the motivating factor and made the car far more fun to drive. For the past decade I'd run the car with no thermostat as I only drive in nice weather and was more interested in keeping temperatures down in stop and go traffic. As I don't drive in traffic anymore, a new thermostat went in at the beginning of the season so now I actually have heat in the car, meaning that fall runs are now possible. Anyway, yesterday I noticed a tiny puddle of antifreeze in the front trunk. You guessed it, heater core is leaking. So the Fiero is going to bed early this year as I'm putting the repair off until the weather is warm next year. I hate when that happens.

Did you find the engine ran OK without the thermostat? I tried it with my 84 (iron duke) and it didn't run very well - it really needs the constant temperature (using a 180 degree tstat). That said, I also tried the 195 degree and overheating was a bit of an issue.

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Mark
1984 Indy Fiero
B O A T - Break Out Another Thousand

It ran fine, just obviously took a little time for the idle to drop. Not sure what thermostat I had in it before but I found that in long traffic jams you could see the temperature rise dangerously high. You could see from the gauge that the thermostat was indeed opening and closing, and you could hear the fan was firing up, but with every cycle the the needle would peg a little higher. Just got sick of sitting in traffic with my heater blowing at full throttle to keep the thing from overheating.

That said, where's the best place to get a non AC heater core in the Durham area? This seems to be a lot more costly part than I thought it would be. Close to $200 CDN with taxes? Can these be rebuilt?

Try calling Partsman in Oshawa for a quote. They are located at the corner of Park & Gibb. We've bought a few from him in the past.

You're other option is to order it direct from rock Auto. They have two brands one is $50 CAD, other is $80 CAD. The $50 part can be shipped to your door all in for $70 CAD

Awesome Thumper. Any idea what the difference would possibly be between the $50 and $80 parts at Rock Auto. I don't mind paying more for quality, I hate paying more for essentially the same thing.

$80 part is better quality and built here in Canada I believe.

Assuming you have the original 1984 4 cylinder like I do, I know exactly what you are talking about. I have a customized aftermarket temp gauge calibrated to the OEM sensor, and it does that up-down thing too but even more dramatically because it does not have that "dead center zone" OEM gauges have. It reacts to the smallest changes.

It seemed to get worse last fall (doing it even at cruising speeds) so this spring I built an ALDL display so I could monitor the second sensor that the ECU reads (it is in a different location on the engine). It is a dramatic difference - the ECU sensor stays pretty even, right at 178 to 180 and climbing to maybe 185 when the other gauge reads well over 200. Because of where the ECU sensor is I believe it is more "accurate" to the real operating temperature - the gauge sensor is reading that bit of fluid right at the top of the block that does not move when the tstat is closed where the ECU sensor is further down. It is like that "high false read" you see when you turn the engine off for a few minutes then back on.

Mine also has the rad fan disconnected from the ECU and on a separate switch which works great - if it climbs a bit I can kick it in manually.

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Mark
1984 Indy Fiero
B O A T - Break Out Another Thousand

BTW the fluctuations with the 195 tstat were much worse and a bit scary - the 180 works great in mine.

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Mark
1984 Indy Fiero
B O A T - Break Out Another Thousand

The Sendor for the ECM sits lower on the engine then the Sensor for the gauge's. When you're coolant level goes lower then the Sensor is, it starts to read the AIR temperature around it and that's what fluctuates the gauge reading. I've had the temp gauge go from normal reading to red hot in an instant then back again. Whenever I see that, I know there's air in the system.

Thanks for the input guys. I believe the thermostat I put in was a 180 degree one, although my memory may be a little off as I actually bought it in the fall of 2015 but couldn't get the thermostat housing cap off, so it was left to the beginning of this summer. Everything seems to work fine, gauge is stable, heater works, and the car works great at all temps. My only concern is that the temp gauge is showing a fairly low reading, maybe sitting at 25% mark. As I recall, it used to sit at about the 60% mark when warm? Wondering if my gauge is a little pooched from not having moved much in the last decade (due to not having a thermostat) or if my temp sensor is not functioning?

When you start your car, does it do the initial sweep test? If so, your gauge should be working fine, unless you modified it to delete the sweep test like I do on my cars.

Whats a sweep test? I assume you mean like when all the gauge lights go on then out one at a time? I can't actually recall if it does that. If so its very quick.

Needle sweeps across the face from low to high, back to low, then jumps to current position somehow indicating the gauge is live.

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Brian
88 GT - 'Ol Blu

Got ya. Cant really check that until the spring now. Battery is out and she's all tucked away for another winter.