Got my 92 z28 sunday and noticed it would start getting warm if let idle for awhile so I flushed the coolant system today and replaced the thermostat with a new 195 one. It seems to cool beter and stays mainy between 190-220 while driving 40+ but when I get to slower speeds or idle it will creep up and the fans will not kick on till around 240 to me this is too late. I did notice on the pass side fan there is a extra plug coming out of the harness but I don't know what it is. Both fans are pluged up and work but just turn on way too late. Anyone have any sugestions? They come on when I turn the a/c on like they should.

 

Before you assume too much - know that these factory guages are simply "pretty features" at best, and are seldom accurate. Have a shop shoot it with a laser temp gun to verify guage accuracy before getting too worried about it.

 

Yeah I know about the faulty gauges but I don't really wanna add any extra ones since I plan to keep the car fairly stock and stock looking know what I mean. Ill shot It with the laser thermo after work but where do I need to point it at?

 

shot it with the laser when the gauge said around 220 the thermostat housing read right about 190ish and when the gauge got to the 240 area the laser picked up the housing at 215-219 when the fans kicked on.

 

I had the same problem, had my mechanic check it out throughly.
even though it's not overheating, the gauge reading is quite worrisome while driving highway speeds. mine "misreads" up to 250 at times, (260 being the max) and it damn near gives me a heart attack when I see that.

is there any way to fix it?, I've tried 3 different temp gauges, all 3 do the same thing.
with varying results..
my gas gauge is faulty as well. (rises when stopping depletes when driving)

 

aftermarket gauges. i did a flush on mine also seems better doing that too.