chasing overheat, and idle issue

[running strong]

So the other day it was like 90 degrees outside, and i was sitting at a stop light when I noticed that my temp was about 2/3 of the way to the hot marker. I slammed on the heater full blast and the temp came back to just under half way. When the light turned green i turned the heater off and the temp gage held. While driving the gage stayed fine. I checked the fans when i got home and made sure that they were spinning. I waited about 4 hours and checked the coolant in the radiator and it was fine. So today i went out to chase this issue and let the car run and idle for about an hour, and there was no overheating. The temp stayed just below the middle of the gage. I don't want to senselessly throw parts at it. There are no leaking hoses either. I'm thinking it's a thermostat or a radiator starting to die. Any opinions on this.

I also have an idle issue. It seems minor. When i start the car cold with the choke closed, the car idles about 2000 rpm. When the car is warm, i have to tap the gas to open the choke and brings the idle down to about 1000 rpm. When i first start driving, the idle will hold between 900 and 1200 rpms, but what ever rpm it idles at it will hold there. After awhile however, the idle starts bouncing between 500 and 1200ish. At times the car feels like it's going to stall. I can manually hold the idle with the gas pedal and it stays fine. I am thinking that there is a vacuum leak to the carb somewhere but i cannot find it. It doesn't make a whistling sound, but i think i hear what sound like a fan between the box and the carb. Is this a normal sound, or is it a vacuum leak?

Also, when turning on the ac compressor the idle becomes steady at 1000 rpms.

[conozo]

There are a few things to check and questions.

-Thermostat are only $15 to replace
-bleed the coolant system
-if your radiator is original, look inside and make sure the fins aren't layered in corrosion.
-Check the seal on your radiator cap, if its cracked it can let air in the system
-How old is your water pump?
-to your knowledge, has the coolant system been maintained or is there rust inside

For the vacuum leak, you can spray carb cleaner at the base of the carb, if it idle increases you have a vacuume leak in that area.

[running strong]

The coolant is kind of an ugly color, I'm going to start by flushing the system first. I have a question. Since the thermostat is cheap, I'm just going to replace it. So when i flush the system I'm going to fill it with water with the old thermostat out. When i run the car with no thermostat, will the car just stay at high idle, and will that be sufficient enough to flush the system?

[Oldblueaccord]

The coolant is kind of an ugly color, I'm going to start by flushing the system first. I have a question. Since the thermostat is cheap, I'm just going to replace it. So when i flush the system I'm going to fill it with water with the old thermostat out. When i run the car with no thermostat, will the car just stay at high idle, and will that be sufficient enough to flush the system?

With the t stat out you can run the garden hose thru there and flush the hell outta it.

[running strong]

I went and bought a new thermostat today since it was cheap, I figured no harm in changing it. When I got home from the parts store I checked the radiator for anything that may be obstructing air flow and this is what I found.
6572
The whole radiator has those pebbles in it and some fins are bent. My question is that would these be enough of a problem to cause the overheat?
It only happens on really hot days in traffic. When it happened it was 90 degrees outside. When it is cooler it doesn't happen.
Both hoses were hot as well, I might be mistaken but shouldn't one of the hoses be cooler than the other?

[Oldblueaccord]

If its more than 10 years old it might be time to swap it out. Clogged tubes and fin damage add up too lost efficency.

[running strong]

That's what I'm afraid of. I have had the car for a year, so i have no idea how old any of the stuff i haven't replaced yet is. I don't want to change the thermostat and have to dump the coolant to replace the radiator. I can't afford one right now so i would have to wait until payday.

[Oldblueaccord]

That's what I'm afraid of. I have had the car for a year, so i have no idea how old any of the stuff i haven't replaced yet is. I don't want to change the thermostat and have to dump the coolant to replace the radiator. I can't afford one right now so i would have to wait until payday.

Depending on your weather you can run water for a while until you figure it out. No sense wasting coolant. I do it all the time.

[running strong]

I'm not sure that i trust the weather here enough this time of year. That thought crossed my mind too

[running strong]

New info on the idle issue. After my vacuum leak test didn't work, i tried a physical and visual inspection of the vacuum lines. They all seem okay. I was driving the car today and when i was sitting at the light, the idle was bouncy it normally does until i released the brake while the light was still red. (flat ground, no traffic) The idle returned to normal and held steady. I went back home and tested that and it seems to be true. The booster vacuum line (i think it's the big one from the intake to the booster) seemed fine,. Could this idle issue be a bad brake booster?
What else could cause the idle to bounce when depressing the brake pedal?