I don't really ever post anything I just stop by every now and then. I have quietly been enjoying being the envy of my friends with my 85 GT Fiero until one day the relay that controls the radiator fan failed. This caused it to boil water out of the overflow bottle. After buying a new relay the fan now works and I have it wired into a switch that controls when the fan comes on and lately I have been running the fan all the time, from the moment I pull out of my driveway to the moment I'm back home. My problem is that it keeps on boiling water out of the overflow bottle. I'm worried that i have a cracked head caused by the engine boiling the first time. My question is what are my options as an Australian fiero owner. I am 17 and will not have the money to fix this car if it is a cracked head.

If it were mine, I'd be inspecting all parts of the cooling system about now. What colour is your coolant now?

Since you're in Australia you are about in the same position I am over here as far as the stock powertrain goes - if something breaks you're kinda boned since neither the Iron Duke nor the 60° V6 were available new in our neck of the woods.

But as I'm sure you'll notice how many of our American friends are doing 3800SC swaps. You and I have a plentiful source of 3800s of our own in the Commodore - the LN3 and Series I in the VN/VP/VR, the Series II in the VS/VT/VX/VY. The L67 3800SC is much less common since nobody really got into the supercharged Commodore S, but they are around. Swapping them isn't always child's play, but it's a possibility if all else fails.

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Have you checked the thermostat to make sure it's functioning properly? Sometimes they are worn, bent or damaged and need to be replaced.

Air bubbles in the cooling system are also a really common problem. Not sure if either of these would be the exact cause of your issue, but I'd be looking into them first (especially if you're unable to afford more costly engine repairs).

I still have my old 2.8 block and a few other bits for the moment, I have been trying to decide what to do with it as I may not be able to continue storing it. It's a difficult decision to make as I know how uncommon they are in Australia.

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James

RHD 1987 Pontiac Fiero GT

Try replacing the radiator cap. If its not holding pressure the coolant will flow out the overflow bottle.

x2

Thanks for all of the responses guys, as far as I know the thermostat is working and the radiator cap is holding pressure, I can't really drive the car for more than 10 minutes without it overflowing out of the overflow bottle. Yet when this happens I can put my hand on the radiator cap and its hot but not so hot that my hand gets burnt or anything. I'm suspecting that I might have a cracked head and if i do then I will just scrap the car.

What if it's just a bad gasket?

If it gets to scrapping it put the whole car in a container and set it over the Tasman to me brother

Probably already have, but have you tried "burping" your coolant system?

Try a radiator leak stop compound. If it works, your problem is probably a head gasket. You may be able to use the car until you get around to fixing it.

quote Originally posted by Cruza: Thanks for all of the responses guys, as far as I know the thermostat is working and the radiator cap is holding pressure, I can't really drive the car for more than 10 minutes without it overflowing out of the overflow bottle. Yet when this happens I can put my hand on the radiator cap and its hot but not so hot that my hand gets burnt or anything. I'm suspecting that I might have a cracked head and if i do then I will just scrap the car.

What'd you ever do with your car Cruza?

quote Originally posted by Big Paul: Probably already have, but have you tried "burping" your coolant system?

I have long suspected that many of the overheating issues reported are due to a failure to perform the correct coolant filling procedure. I've never had a need to it myself but it is more than just filling the reservoir to the line. These is a very specific set of steps that must be performed to make it function correctly.

Maybe someone has a procedure, or a link, to how those steps are performed.

X3 on the radiator cap, my 86GT was doing the same thing - weak cap wouldn't hold pressure and pumped
coolant into the overflow tank until it ran out. The engine fill cap is higher than the radiator cap, a lot of
antifreeze can be pushed out by a bad cap. Just filling the radiator leaves a large air pocket in the engine.

To fill, remove the radiator cap, the engine cap and pull out the thermostat from the housing.
Add antifreeze to the engine until it starts to come out the radiator then put the radiator cap back on.
Fill the engine until full, put engine cap back on. Start engine for a minute to circulate water & get out air bubbles.
Remove engine cap & fill to the top, put thermostat back in and replace engine cap.

Warm the engine up & make sure the overflow tank is at the correct level, when the engine cools down it will
pull in more coolant if the system still had some air in it (if the radiator cap is working).

If it got hot it might be a good idea to replace the thermostat and radiator cap.

[This message has been edited by AL68 (edited 01-09-2015).]

I can not believe this has not been asked already, but what is your coolant temperature showing when it starts boiling over? The 85 GT came with the Aux gauges correct?

Negative on the rally gauges in the '85 GT John.

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quote Originally posted by Carcenomy: Negative on the rally gauges in the '85 GT John.

Idiosyncrasies with the Fiero never cease to amaze me Stuff like the 85 GT tail lights will not fit any other Fiero GT year

A quick test of the thermostat is at least simple. Take out the thermostat, and see still over heats. It is worth doing even if you are certain that is not what it is, just cuz it is fool proof and simple.

[This message has been edited by JohnWPB (edited 01-09-2015).]

See my Cave, Radiator Caps, Coolant Fill and rest of coolant section.

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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 (It's also at the top and bottom of every forum page...)

[This message has been edited by theogre (edited 01-09-2015).]

Replace the fan with a VR or VS commodore fan $10 at wrecker. Old thread but worth doing. The fiero fan spins so weak you could stop it with hands (don't recommend it incase yours works) but found the stock electric motor weak.