I live in the mountains of vermont and on my way home from work ,its a solid steep 8 min climb to my driveway. When i pull in the drive way , the temp on my 86 , hits 215 ,then when i shut the motor off ,with the key still on i see the temp climb,till 240, and at 238 a fan thats out of sight behind the radiator kicks on, but NOT the fan you can see, "the big one" after 5 min the temp is back down to 220. Today was 91 at 5pm. if that factors in. The coolant is very dark and ugly, i think i will change it tomorrow. I welcome all opinions on this, im a newbie to corvettes. Thanks Also is it normal the engine temp climbs when i shut the engin off?

 

Would you recomend swapping out the t stat to 180, i dont drive the car in the winter. Also why wouldnt the "big" fan kick on. All i hear the little fan screaming away.

 

I'd bet that your radiator is mostly clogged like mine was, especially with the coolant being so dark. 240 temps can easily ruin your rings which means a new engine - 3 guesses how I know.

A radiator is fairly cheap $125 or so. Also get a "fan switch" that turns on the fans earlier. Once you're moving at 40+ the fans don't do anything it's all airflow at that point. That's why I'm betting your radiator is clogged.

A lower temp stat will be okay if you fix the mechanical problems but otherwise will just make the overheating worse.

 

This temp topic has been covered a million times. I routinely run at 220-230. Sitting will creep to 240. I hate it but what can I do ? It only happens once in awhile but none the less happens. Never above 240 but 230-235 isn't uncommon for me here in Mesa AZ. I will yank that stock radiator out when I get a chance and put a chinese 2 row 1" each and hopefully that will prevent going over 220. I thought that 220 was not a problem at all and not to be concerned. for that matter if GM doesn't have my auxiliary fan come on till 230+ it must not be danger zone. If yes I will stop driving my car till I can change out the radiator.

 

This temp topic has been covered a million times. I routinely run at 220-230. Sitting will creep to 240. I hate it but what can I do ? It only happens once in awhile but none the less happens. Never above 240 but 230-235 isn't uncommon for me here in Mesa AZ. I will yank that stock radiator out when I get a chance and put a chinese 2 row 1" each and hopefully that will prevent going over 220. I thought that 220 was not a problem at all and not to be concerned. For that matter if GM doesn't have my auxiliary fan come on till 230+ it must not be danger zone. If yes I will stop driving my car till I can change out the radiator.

 

Under those conditions your car is doing very GOOD...

Mine would hit 240+ climbing a long grade in 90 degree ambient and I've got almost every cooling system upgrade that's been made..
I recall the temps while driving the mountains in Az or Ca in the summer...

To answer the fan question...
the primary fan is ECM controlled and the ECM is semi dormant when the engine is off and key is ON. Its not going to react to anything unless the engine is running...so the main fan sits still. Temp rises due to the coolant not flowing to drop off heat in the radiator. The block is still very hot and the second that coolant stops moving the heat is trapped there where the CTS (sensor) is.

The aux fan (that can't be seen) is on a simple switch that is activated as soon as that switch reaches 230 degrees give or take, thru a ground. The switch itself is the ground, so whenever there is power to the switch, and a ground path, the fan runs. That fan is mounted in front of the condenser and CAN be seen by looking up, in the nose at the a/c condenser. That fan is very good for collecting trash and will eventually catch something that will break a blade or just cause it to burn up. Its NOT a 'gotta have' item..in fact it was added by dealerships in response to owners freaking out when they saw their car hit 230 in traffic with the a/c running,.,..it really does little to help. Its a placebo if anything. The car cools by forward motion. Yes, it gets hot sitting still. It has no access to fresh air until its moving. The main fan was designed to fill in those gaps where the car sits and idles and the ECM turns that main fan off after the car reaches a certain speed. About 35 mph IIRC...

To clean the radiator of leaves and grocery store bags and news papers, you MUST take the top radiator shroud off and dig the debris out that's between the radiator and the a/c condenser. There is NO way to see this, or access it without taking the top shroud off. 1st time is hardest, but if you make some simple modifications by a couple cuts on the shroud it is a 10 minute job the next time. Just 'slot' the part that passes over a hose and the trans cooler lines. Cake after that.
beware the dead things that live between the rad and condenser...there will be fur, feathers and sometimes bones. You don't wanna know...

Buying a FSM set will be the best investment you will EVER make if you plan on doing much at home service of the car. Search FleaBay for used sets for $75.

Flush the system, refill with good clean green coolant or whatever you like, (just be damn sure its compatible) and clean the debris out of the airstream and you're good to go.

 

wow, that was very informative, thanks very much.

 

holy .... makes since why my main fan wont work.. i have nooo speedooo so ur saying the fan cuts off at 45mph give or take?? wait wouldnt my fan just not stop running?? or is there a cut off in power cause the connector isnt hooked up??

 

What leesvet said...............Clean the junk out that might be in front of and behind your rad, and then make sure the radiator has no air in it, put it on an incline and then park it on an incline, take the rad cap off, then let it idle and get to temp, then check to make sure you have decent circulation, and check the coolant level

 

My car has 20 miles from restore.. No cruise, EGR, Th350 swap 88 tpi so idk might just put a switch on everything