4th vs 5th gear over heat (with bumper block and belly pan)
 

I was driving up the canyon in the snow. I could not go that fast. I was trying to stay in 5th gear but had shift down to 4th. Was in 4th for a bit and was driving at 3000 or + a little bit. I noticed my temps on my scan gauge going up. It has gone up from 182f to 198f with out the needle moving. But this time it the needle got up to the 3/4 mark just under the red line. This is the second time I have noticed the needle moving.

Has anyone had this problem before?

60+ mph overheat
 

after iinstalling my bellypan and upper and lower grill block my car would get too hot at any speed over 60, so i cut a small opening in the lower grill block and problem solved,, but also make sure you have enough coolent, i was a little low and that was also contributing to my problem.

I might suggest that you install a thermostatically controlled air door on your grille or bumper block that would open as to your set point to regulate your temp.

over heat
 

I have the problem for CRX,D-100,and T-100.I anticipate the higher load at lower 'ram' velocity and run heat setting to maximum,turn blower to highest speed using the heater core as an auxiliary radiator until 'past' the situation.
A manual control for an electric cooling fan would take care of it,but since I'm a 'flat-lander' the situations are rare.

Overheating?
 

Aerohead is right on this one and I have used this trick many times, with the heat on full blast and the windows down. Climbing these long mountain passes will make the coolant heat up. I did have a question for the OP. Did your car boil or steam? Are you sure it overheated? Personally, I don't get too concerned if the Scanguage reads 205º or even higher. Boiling is 212º at sea level and you have a 15 lb. pressure cap on you radiator that raises the boiling point even higher. Also, on most modern cars the temperature guage acts more like an "idiot light". You can see the actual temperature on the Scanguage and the factory temperature guage doesn't move. I trust the Scanguage to tell me what is really going on. But as always, buyer beware, it may be better to open up your grill block before you go to the mountains than to cook your engine.

over heat
 

CO,that's a good question.
What I've observed,is that if I do not remove some of the heat flux from the cooling system on the ascent,and then pull into a filling station and park;once the engine is turned off ,the coolant will boil out into the over-flow receiver,with some spilling to the ground.Bad!!!!!!!!!! Ethlyene glycol Bad!!!!!!!! It makes me feel like a *%&$#@)(+_<>?@#!
This is at 8600-feet at Cloudcroft,NM where baro pressure is reduced.If I run the heater fan,the problem goes away.
This used to happen to me close to sea-level in my El Camino with the 396 c.i. big-block,say,waiting in line at a drive-in theater in Van Nuys,Calif.This is probably where I used the trick for the 1st time.I'd blame my girlfriend.

Louvers in the hood behind the radiator where the air that is kicked up off of the front/nose will lift out the hot air behind the radiator?

I try to NEVER shut the engine off when it has just been pulling hard, especially in a turbo car. In the mountains, even a brief downhill will drop temperatures very quickly with the engine running to circulate coolant.

Cooling issues
 

I agree with most everything brought up here. I'm in a similar boat, with my Jeep contantly running at 207 (normal for the engine), but it doesn't leave me a lot of room to get much hotter before there is an issue. I'm still in the planning phase of my grillblock, but I'm planning on solving the issue of "emergency cooling" with a actuator moter powered scoop that would open to "force" cold air from the front to radiator instead of around it. I'm still working out the logistics, but I'm making the whole thing from fiberglass but using cardboard as an analogue.

what you have to remember is that the grill is there for a reason, so adding a little opening is no sin, you could have a little manual shutter for these occasions or leave a small opening all the time... this could actually be enough to allow the fan to controle the situation, and if this situation don't occur very often, the fan is a good and safe solution.

i only tend to build up heat when stuck in stop go traffic and barely moving, as soon as i pick up a little speed the small hole i left is enough to bring things down to normal levels.

also if you overheat at low speeds where the ram effect trough the grill is small, so a hole anywhere (ie the bottom in front the the rad) where the fan can collect fresh air might work.