fiero cooling system

Join Date: Sep 2005


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the cooling system is on my fiero is messing up. I can let it idle in my driveway for about a half an hour or so and it is fine. the hoses have a lot of pressure on them though.I let it cool down and check the coolant level and it is fine.But when i drive it to the corner and back all the fluid is coming out of the overflow. I replaced the radiator cap,radiator,,waterpump i replaced the radiator hoses i havent replaced the one that goes into the bottom of the waterpump yet was put in last year,replaced the alternator,drive belt ,all gaskets from the head on up, i am not sure what is going on with it but any insight is greatly appreciated. The thermostat is even new I took the t stat out too and drove it and it did the same thing

I have another question I have my fan hooked up to a toggle switch for right now. I replaced the other hose on the water pump the lower one. If my temperature sensor is bad would that cause for the build up in pressure? cause i called an auto store and they said that it would cause a build up of pressure because it is not telling the computer what to do.The temperature gauge is reading around 130 when this happens

How about a cracked or warped head would that cause the build up of pressure in the cooling system? The car runs and idles great If I have the heads milled you think that might work? or

Modern cooling systems are designed to build pressure. It lowers the boiling point of the coolant, so in that respect your system seems to be working correctly despite what the parts guy might say about the sensor!

My 2.8 is notorious for spewing coolant from the bottle ***if*** it's overfull.
On most Fieros I've seen the overflow tank is kept at the low mark on the tank when the engine is cold any more than that & it'll spit the rest.

The front cap, the one on the rad....I can't recall off hand but there's a specific cap for it. If you get your cap from CTC it'll be the wrong one.
Been there done that! After it's all said & done it's the front cap that controls the pressure. Spend the few extra bucks & get the proper one from GM!

Good Luck

I believe i found the problem. i did a pressure test on it and the pressure was going down slowly so i examined the heads a little bit closer plus a few of the other cooling components well the place i took to put my new heads and head gaskets to didnt tighten some of the bolts down all the way so it was drawing air in throughg the head thanks for the help

Well tighting the bolts down didnt do much good. I did a pressure test and it didnt go down i ordered another radiator cap i believe is rated at 18 . Mine is a 86 gt 2.8 I'm getting a code 35 so i must have an air leak or a bad iac. not sure what else to do at this point but wait for my new cap and see what happens. Is there two temp sensors one for the gages and the other to tell the ecm to go into loop or not if that one isnt working properly would that cause any problems with the circulation? I believe that the one for the ecm is next to or below the filler neck? there is no milky looking oil either the temp light doesnt come on when i turn the key to the on position. it used to have a/c in it but the guy i bought it off of took it out as well as the cruise control

If the heads were not torqued down properly there is a good posibility that you have a warped or cracked head or a blown head gasket. Contact the shop that did the work for you, tell them what you found and see what they will do for you. If they refuse to do nothing, find another mechanic, have the heads pulled and checked and new gaskets installed if the heads are ok. This should stop your coolant problem.

Yes, the sending unit for the dash mounted temperature gauge is separate from the sensor used to signal the ECM. Despite what anyone at Canadian Tire might tell you, the CTS does NOT control cooling system pressure. It merely reports coolant temperature to the ECM, and the ECM decides when and whether to turn on the radiator fan up front and blower in the engine compartment (if your car has one). As bmcf reminded you, the pressure cap up front limits the cooling system pressure, nothing else. If the V-6 has a cap in the rear, it is only a fill point and may hold the thermostat in position (like the L4s) - There is no pressure relief in it.

well i took it back to the shop they said everything looks fine and the guy that did the job doesnt work there anymore he got fired. and he was the same one that put my radiator in for me so i figured i better take a closer look at that as well. by the looks of things he didnt flush the old coolant out and there were alot of rust particles or something the kinda resembled slate rock but much more brittle. so i took the radiator out of the car and ran water thru it until no more particles could be found then i did the same to the lines on the car.I'm not sure about this 50/50 thing with the coolant but i put the whole gallon of antifreeze in the car and about a half a gallon of water in it so far but i yet to start the car and burp the system and then drive it. so i am hoping that this fixes my problems. and the rad cap that i order is 16 psi and vented when i ordered non vented. hopefully it wont create too much of problem. cause i might try it with the vented. or send it back and wait for the right one. This car runs excellent i replaced the iac valve i think it was like 41.00 for that little thing and it made a whole world of difference with the way my car was running. the only problem now is getting the cooling back on track. i bought off this guy for 500 an put about 2000 in it already

how much coolant does is tpically take to fill the 86 pontiac fiero gt 2.8?
Wouldnt the oil have some sort of discoloration if i did have a cracked or warpedhead?
another thing i noticed is that my oil presure goes way up too high and my fuel pump atys on if i leave the oipressure sensor hooked up

I got the cooling ystem fixed now i have to deal with it burning rich thanks for all the help

the map sensor was making it rich

You are experiencing the fun of a Fiero (or any other 20 year old car on the road). You fix one thing then find something else wrong. Hopefully repair costs are less than car payments.:shakehead

Ive been doing my own repairs since the incident with the heads i just bought a map sensor for 60$ parts for this car sure arent cheap