My wife and I bought a 94 Z28, Corvette heads, K&N, Edel headers, 3" Borla Exhaust, 2800 stall converter. The temp gauge shows that it is running 2/3 of the distance between half and three quarters. It WAS running at 3/4, I drained the radiator twice and filled it with a 60/40 mix and a bottle of Water Wetter. I left the drained coolant in the bin over night and there was some sediment on the bottom and it was a cherry orange color.
I did change the thermo. and drilled a 3/32 hole in it.
THe fans do come on but they come on and shut off TWICE before the gauge hits half way.

ANY ideas? I'm going to make an appt to have the cooling system flushed.

Thanks in advance...
Eric

 

Did you clear the system of air???

 

Did you vent the air out of the coolant system correctly? That will really screw up the LT1's reverse-flow cooling system if you didn't.

Why did you drill a hole in the t'stat? Are you sure you have the correct t-stat for the LT1 engine? Its not the same as the other SBC's. What temp is the t'stat? Stock is 180*F.

The stock fan setup turns the first fan (early 94's; low speed on later 94's) at 226*F and the 2nd fan (or high speed) at 235*F. You indicate your fans are turning on and off twice BEFORE the dash gauge reaches the 1/2-point (~210*F). Not tight. Does the SES light cycle on an off at the same time the fans turn on/off? Have you checked the accuracy of the dash gauge? The gauge is driven off a single-wire temp sensor in the driver's side head. The PCM reads the 2-wire sensor in the water pump housing to control the fans.

Do the fans run at all when the gauge indicates the coolant is approaching the red zone? You may have to put a scanner on it and see what the coolant temp sensor in the water pump housing is reporting.

 

yeah i been battling overheating problems lately too, thanks injuneer you answered something ive been trying to find out for 2 days about which sensor controls the fans n such. i got some heavy duty flush in mine right now it said to ride on it for 3-6 hours so imma try that. mine hasnt ran "hot" to the point its boiling out but the temp gets up higher then normal and higher then id like. but the guage and the scanmaster seem to read different at times

 

When I reached 100k miles I flushed the system with a prepared flush, lots of water, drained the block too... and filled it 40/60 with permanent Antifreeze. 8 months later all my good efforts produced a blockage in the radiator so bad that when the hoses blew off at 55 miles per hour my son said it looks like an asteroid entering the atmosphere. I looked in the mirror and knew he ws right. Next stop new ...radiator no problems since at 158 k. I think the flush chemical reacted with radiatot metal and the permanent antifreeze and form a solid.

 

I think so, it's definately running cooler than it was.

I think it's vented, it's running cooler than it was. I drilled the holes in the TS to aid in removing air and coolant circulation. It's a TS fom Advanced Auto and I think it was 190*.
After seeing the sedimant on the bottom of the drain pan, I think it would be wise to have the cooling system drained, flushed and refilled and use some water wetter, and see where that gets me.
But that was some good info on the fans, I will have to throw it on the computer.

 

Are you sure you have the correct LT1 thermostat:

http://shbox.com/1/tstat.jpg

Running 190* 'stat isn't a very good idea. Hotter than stock. It only starts to open at 190*F, and isn't fully open to about 210*F... about mid-point on the coolant temp gauge.

I've been running the same Hypertech 160*F 'stat for 13 years, and never had a problem with engine cooling.... even when the engine is pumping out 800HP on a 300-shot of nitrous. Only difference between my setup and the stocker is the t'stat and a Griffin radiator.

 

I dont believe you can get a 190* for the LT1, so it must be for a traditional sbc. Seriously though it sounds like your system is not bled properly, if you did you would be positive, not maybe.
Also it sounds like the sediment is the original dexcool, the factory coolant

 

94's did not leave the factory with Dex-Cool.

 

Sorry, thought they did because when I got my 94 it had dex cool in it. Well if its an orange sediment could also be rust in the radiator.