First off, the car in question isn't a third gen, it's a 87 Fiero GT that I swapped a chevy 350 into. That being said, I'm at my wits end and have exhausted every idea that I've had regarding this. The unique thing about this is that the coolant is not really getting that hot. No, there isn't air in the cooling system, but for whatever reason, the top end of this engine is blistering hot in a matter of 2 minutes after starting the car. The coolant however is still onlly around 100 degrees. At this point, if you put your hand on the intake manifold or valve covers it could probably burn your skin pretty easily. Anyone ever heard of anything like this before?

Here's some additional background. The engine is a 350 bored .060" over. The heads are crappy junkyard heads (1.94/1.5). I lapped the valves and put new seals and springs on but that's all I did for the heads. The lower end of the engine was completely rebuilt and the cam is a lunatti with .507" lift on intake and exhaust. Neither the lifters nor the rockers are roller so there is a good deal of friction in this engine but it shouldn't be contributing to this much heat. The water pump is a CSI electric and the stock radiator was replaced with a oversized aluminum one exactly like the local guys all use in their circle track cars.

Please if you've got any suggestions I'd like to hear them. Like I said, I have tried almost everything I can think of and have had no luck so I'm open to any suggestions.

 

a 350 in a fierro? I bet that will fly, however this post will probably be locked

 

perhaps the thermostat is stuck. Might explain why the reading is low and the top is hot (depending on where the temp sensor is at)

 

I've tried running it with the thermostat removed and the result is exactly the same. Thanks for the suggestion though.

 

hmm ok... I dunno.. i dobt you would put a reverse flow intake on it by accident... or water pump... but that could easly cause that problem. Other than that no idea.. I know my 305 used to get hot as hell.... until i changed the timing and adjusted the carb so it was not lean.

 

I would wonder how accurate that 100 degree coolant temperature is as well. How are you determining this "fact"? Hopefully not with the notoriously inaccurate in-dash factory temperature guage......

 

Really. I have two temp guages in my car one in the new digital dash i have, and one that is not part of the dash. One on both sides of the engine the dash one is what i cll the "cool" one as it is in the stock location. My other guage hits 220 before the other guage leaves 100 to 115 then the thermostate opens up and they both level off at 190-200

 

The intake is an old holley street dominator. NOT the newer street avenger. I certainly don't think that would be a reverse flow intake.

I set the timing with a timing light so that shouldn't be the issue either. The engine actually runs very good. The power is there, but it just gets too hot to use it within a few minutes.

As for the gauge being off, I agree that you can't put much merit into the factory gauges. However, the thermostat housing remains cool long after the intake and valve covers are nice and roasty. Also, the temperature sensor which controls the electric fan for the radiator is located in the intake. (the sending unit for the gauge is in the head). I know that the fan switch is supposed to close the circuit for the fan at 220F and shut off again at 190F. Sure enough, the fan turns on and off when the guage is indicating those temperatures. That would leave me to believe that there is at least some truth to what the gauge is indicating. Otherwise the fan would switch on long before the gauge would indicate that it's up to that temp.

I'm very close, now, to just pulling the intake off and checking the manifold gaskets to see if I mistakenly put the wrong gaskets on and covered a coolant passage or something. Anyone think that is possible? I know that coolant does flow throughout the system because the radiator will infact warm up and you can feel the flow if you put your hand on one of the hoses, but I wonder if it might be partially obstructed or something???

 

possible.. i am out of ideas. but then my car is sidelined now. my 700r4 finally kicked the bucket on the way home from picking up my brother from work.. And wouldn't you know.. the second it drops the gears and free revs and then slams into the next gear and launches me uncontrollably, there is a retard cop who wants to give me a ticket