Well it finally hit 100 here and my 88 fiero with a 4.9 decided it s to hot. Anyone have any answers on over heating I didn't have a problem till it hit the ninteys . It runs a little warm at 75 miles per hour but as soon as I get to where I'm going and shut dpwn it boils over . I start it up to idle to cool it down and the gauge pegs no a/c on. I replaced the thermo with a 180 and new radiator cap no help. I don't know if the Fiero factory put in a larger radiator when they did the swap. Any answers please I would like to drive it in the summer too.
Fan is running Radiator is probably the stock V6 since this is a formula. I'm wondering if I remove the screens from the bottoms of the engine vent grills this should help me remove more engine heat they restrict a lot of heat removal from the engine compartment. Is there anyway to get more air to the radiator? Or would a larger one help.
Even if you have the 2.8 radiator it could easily be partially plugged if its the original radiator.
That's what i was thinking too. When my car started to run 20 degrees higher than normal, i took it to the radiator shop. He removed the side tank and hooked up a hose. About 1/2 the tubes were partially or totally blocked. The guy ran a swab through each tube until flow was restored. Now it's good as new .
Boiling over could be a sign your system can't hold pressure. Get the "loaner tool" radiator pressure tester from Autozone. Not sure if O'reillys or the other stores carry it. I had a similar problem and found at least 3 places where fluid was leaking. It is easy to find the leaks as the tool pressurizes the system and you can hear/see them. This simple tool stopped the head scratching and parts replacement mode.
[This message has been edited by flimbob (edited 05-30-2014).]
You could have the wrong radiator cap. You need the kind where the little vent in the center of the underside of the cap is spring loaded, so that it stays closed. If you have the kind where the little vent dangles loose, it won't work on a Fiero.
The car only has 48000 miles on it so I don't think its a radiator problem . I bought the correct cap. I'll try the pressure leak check though I can't find any leaks when it sits and idles. Can't wait to drive it when it hits 115 degrees and I definitely need to have the air on. P.S. I found a good way to add cup holders I drilled 2 2 3/4 inch holes in the center armrest back of the liter and inserted chrome golf cart cup rings a nice clean install. I don't know how to show the picture of the installation.