Fellas,
I just completed getting my Fiero back on the road after seven years! 😀 My problem: (1) I bought a new thermostat
(2) I bought a new radiator
(3) I bought a new radiator cap
(4) I bought a new thermostat cap
(5) I bought a new temp switch
(6) I bought a new oxygen sensor (Bosch)
(7) I bought a '88 thermostat housing
(8h I bought a new sensor that plugs into that thermostat housing
With all that I drove maybe 1 mile and the engine gets HOT🔥 What didn't I buy? I added water, but maybe not enough? That's all I can think of ? Oh' I changed the oil and added all the anti-freeze to specs
Cordially,
kevin

[This message has been edited by kevin (edited 06-10-2015).]

What is hot in one mile? Feel the radiator and the coolant pipes to confirm coolant is moving. Air pockets in the cooling system are to be expected, and should work themselves out.

http://home.comcast.net/~fierocave/coolfill.htm

[This message has been edited by Gall757 (edited 06-10-2015).]

All car engines get hot after driving a mile.

Are your coolant tubes pinched or crushed? Most shops, even when Fiero's were new, didn't know how to properly lift the car. Check behind the front wheel wells and in front of the rear wheel wells.

After i fixed/repaired mine in three different spots it never gets above 215 deg with a stock thermostat and Rodneys low temp switch.

Like the exhaust system any restriction is not good.

[This message has been edited by KMFDMFAN (edited 06-10-2015).]

Water pump was not on the list - If the car sat seven years I'd at least be worried about the impeller rusting away....... are you sure it's working?

quote Originally posted by kevin: I drove maybe 1 mile and the engine gets HOT 🔥

Define "hot".

The temp gauge in the dash is next to useless. Have you verified with a scanner how hot the engine is actually getting?

quote Originally posted by kevin: I added water, but maybe not enough?

I've used the following procedure with half a dozen different Fieros and never had an overheating issue...

quote Originally posted by Patrick: * Make sure rad cap is the proper one for Fiero use. The catalogs are wrong! You want a non-vented one, * Check that the overflow tank and the small hose to the rad are both in good shape. Otherwise air gets sucked in. * Ensure that coolant level in overflow tank is at the "Cold" level. * Position rear end of Fiero higher than the front. * Remove thermostat housing cap and thermostat... and then add coolant to thermostat housing with rad cap also removed until coolant runs out the top of the radiator. * Re-install rad cap. * Continue to add coolant until you see the level come up to where the thermostat normally sits. * Put thermostat cap on and turn just barely enough to hold cap on. * Start engine and run for about 30 seconds. * Remove thermostat cap and check coolant level. * Repeat last four steps until coolant level no longer drops. * Re-install thermostat and thermostat housing cap. As long as there are no blockages anywhere in the cooling system and the water pump is circulating coolant, you should be good to go.

[This message has been edited by Patrick (edited 06-10-2015).]

Fellas,
I think it is remarkable how much knowledge the ''Fieronistas" have!! Truely outstanding. What I think is going on withe my Fiero is a lack of water/coolant. I have a new water pump (I forgot to mention that) and have no bent or cracked coolant tubes. I am going to add more water with the ass up in the air and the radiator cap off. I'll keep adding water at the Thermostat until it leaves out at the radiator cap. I believe that should cure my overheating issue. By the way, I ran the car for 17 minutes before the need rested on the red zone and the idiot light came.
I'll keep you all posted tomorrow morning. I have to drive it to a SMOG station tomorrow and I don't want to fail. It seems the pegged hot needle was my big issue. Thanks again for all your valuable insight.
Cordially,
Kevin

My thermostat went on my way for emissions so I pulled it and passed with the car in closed loop.

Btw You sure you aren't losing coolant? I had my waterpump loosen up some about 2k after it was installed

While we are still on this subject let me interject my issue.

I have an 85 GT (haven't had it very long), 49k miles, superb condition. Today it was 90F in New Jersey and I got stuck in traffic going to work. As I was inching along in traffic I noticed the temp gauge was in the red zone. I pulled over and shut it off to let it cool down. Then I continued to finish my journey to work.

I watched it closely going home and it is at about 160 to 190F continuously as long as the car is traveling at 40 or more mph but when I have to slow down and sit in traffic it starts to creep up again. I have learned on this thread that there can be air pockets in the system and the coolant may be low and the thermostat may need to be changed and the water pump may need to be changed. Keeping in mind that the car only has 49k on it, which resolution do you think I should address first?

I am thinking of backing up onto my ramps and doing the back to front and front to back fill procedure, but if there were air pockets in the coolant system, would it run find at high speed?

Thanks for any help you can offer.

quote Originally posted by QCMANAGER: I watched it closely going home and it is at about 160 to 190F continuously as long as the car is traveling at 40 or more mph but when I have to slow down and sit in traffic it starts to creep up again.

You never mentioned whether or not your rad fan ever comes on.

quote Originally posted by QCMANAGER: ...which resolution do you think I should address first?

It would probably take you less time to simply follow the steps I've outlined above than for us to discuss them individually.

quote Originally posted by QCMANAGER: While we are still on this subject let me interject my issue. I have an 85 GT (haven't had it very long), 49k miles, superb condition. Today it was 90F in New Jersey and I got stuck in traffic going to work. As I was inching along in traffic I noticed the temp gauge was in the red zone. I pulled over and shut it off to let it cool down. Then I continued to finish my journey to work. I watched it closely going home and it is at about 160 to 190F continuously as long as the car is traveling at 40 or more mph but when I have to slow down and sit in traffic it starts to creep up again. I have learned on this thread that there can be air pockets in the system and the coolant may be low and the thermostat may need to be changed and the water pump may need to be changed. Keeping in mind that the car only has 49k on it, which resolution do you think I should address first? I am thinking of backing up onto my ramps and doing the back to front and front to back fill procedure, but if there were air pockets in the coolant system, would it run find at high speed? Thanks for any help you can offer.

I also have an 85 GT that had sat for awhile before I got it. When I first started driving it after changing all fluids it would do what yours is doing. On my cat it turned out to be a bad water pump. When I took the old one off the impeller was all rusty and clogged.

As a previous post asked, have you checked to see if you radiator fan comes on? If not it could be the temp switch at the engine block (which you say you have already replaced), the cooling fan relay (in front of the left headlight), or, less likely, the fan motor itself.

Cool driving and overheating in traffic are 2 good signs the fans are not working. If I remember the fans are set on by the fan switch (sensor by the thermostat housing) to come on at 230* and shut back off around 190*. Rodneys switch drops that to like 185-210*. You need to verify the fans come on when the temp gets up to the red at minimum. They also come on when you turn the AC on at all temps.