First of all I want to say that I have replaced the following:

Water Pump (Definitely needed replaced)
Thermostat housing (Cracked)
Thermostat (Was good, replaced with same temp anyway)
Radiator Cap (Not sure if it was bad, but it was the first thing to do)

Question 1: When my temperature gauge says ~260 the fan for 230 come on (driver side) , and looking at the temperature in a scanner says that the temp is actually ~230

Should I ignore the gauge when it says it that hot since the scanner says otherwise?

Question 2: With all of those things replaced, the car still is running hot. I have flushed the radiator several times and felt all the hoses (definitely hot).

Is it time for a new radiator?

Question 3: Is the overflow tank supposed to be pressurized also? The seal on my cap is gone

I have a 1987 IROC-Z with a 305 (two fan setup)

Sorry I seem so formal, it's just been one problem after another and I'm out of ideas.

Additional Info: I'm pretty sure it's not a blown head gasket, there's NO loss of coolant, no water in oil, and no colored exhaust.

The only thing that's happening is after driving my car for an extended period of time (15 miles at 30 minutes with an average speed of 45 or so) the overflow tank will start filling up rapidly.

 

Very good post first of all. Nice and informative. Very well laid out.

Question 1. The fan is supposed to come on around 220-230. You say it comes on while the scanner shows about 230*. Sounds like it's working like it's supposed to.

Question 2. How hot is it running? Like I already stated in question 1, the fan isn't supposed to come on til about 222*F

Question 3. No, the overflow isn't pressurized. You can take that plastic cap off even when it's hot.

 

Thanks

The car was idling at a steady 222-223 temperature, I can only assume it's the same, if not just a bit hotter, when driving around (since the temperature gauge was in the same area the whole time)

I should probably mention that I've been having a lot of trouble with rust (or at least, brown radiator fluid that settles back to green), which is why I've flushed the radiator several times, could this easily cause the problem?

 

I've got an 88. When I let it sit at idle for awhile it runs a that temp too. That's provided the ambient temp isn't real cold. There is no air going into the radiator at idle. As you know there isn't much of a grille area letting in air in these cars. Especially just idling.

 

Yeah, actually I'm wrong about what I said earlier, the temperature gauge went down at times when I got around 50 MPH or so..

I'm just really concerned as to why I had a ton of coolant in my overflow tank, well past the limit for hot coolant.. Don't want to actually blow a head gasket :/

 

I wonder if your radiator is partially plugged? I assume the coolant level in the overflow is lower before it gets hot? I'm thinking maybe if the radiator is partially plugged it may be backing up in the overflow when it gets hot.

Maybe a radiator shop could check it out. I do see a new one on ebay for $93 bucks plus about $14 shipping. I don't know what a parts store charges.

 

I think you're probably right, I'll know for sure tomorrow (I'll switch radiators with our other Camaro, I know that one works just fine.)

Thank you very much, I'll post back tomorrow if you're interested

Correct, the "Cool" level is where it starts, and at the end it was up to about a half inch to a 3/4 inch past the "Hot" part

 

You have another car available that you can just pull a radiator from? I'm like you, since you flushed the radiator several times and, are still having alot of rust problems, it's a concern. I am interested in what you find out.

 

Yeah, we also have a 1989 Iroc Vert that recently had a new radiator put in it. (And the previous owner never put a thermostat in.. ) So if I take the radiator from that car then I should know if it's the radiator or not.

I should post sometime around 6 or 7 PST, don't hold me to it though cause something could always come up. I will make sure I post my results though

 

Well I'm doing homework atm.. Probably won't get to work on the car until Friday/Saturday. But what I'm going to do is completely flush the rust out of the block the same way that professionals do, so that way all the rust crap is out. THEN I'll know if the rust was the problem.

 

Great, let us know how you come out.