cv67

If you want the fins of the rad. and condenser really clean take a water hose and spray a strong stream from the backside (engine side) of the radiator over and over and over. If you can follow up with compressed air even better.

If you have the radiator out of the car hold it up to light youd be amazed how much stuff plugs the fins up even if it "looks" clean.

Rinse repeat til clear will make a noticeable difference.

scrappy76

Lots good work there. Real quick like. You must want to get this thing rolling.
The air dam is the lower front spoiler. Its at the bottom and if its stock, it will be about 2"-21/2" wide and usually black. Make sure its there. Also, I assume the color of whats inside the Radiator is either green,purple,or orange. Its its rusty or clear, you need to drain the radiator and add a mixture of antifreeze/coolant and water. I usually do one gallon of coolant, then top off with water.

65GGvert

Ask me what can happen to a hot aluminum radiator if you spray it with cold water.

corvettesummer79

its my 16 yr old sons everyday driver he drove it to school today
gonna try and get him to flush it out. painted and put the front spoiler on over a year ago thanks guys

OMF

At the risk of thread drift.....OK what happens?? I did it, and lots of other guys did it at the track.....no troubles.

corvettesummer79

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65GGvert

I had a 65 that overheated back in the early 70's. I pulled over and borrowed a water hose from a service station (remember those?) and sprayed the radiator. It popped and cracked and started spraying water out the split in the aluminum.

kdf1986

I think the problem is with the missing top radiator seal in his first post.

hosed off condenser and rad. missing middle top seal. antifreeze looks clean

Without this in place the air is forced over the radiator instead of through the radiator. This would lead to hotter engine temperatures.

kdf

vette_jim

By chance do you have your heater core bypassed (heater hose looped back toward engine). I had to do this in a pinch once, caused 15 + degree increase in temperature on my 73.

commander_47

These cars tend to run a little warmer than most anyways. It is normally not an issue. My car normally hovers around 190-200, but at highway speeds for any length of time can stay at around 210.

This used to concern me considerably and I spent years trying to figure a way to cool it down. After spending a long time talking to the Chevy dealers mechanics, I was convinced this is a non issue.

You don't have to worry until the car starts getting near the red, which is about 250.

Having said the above.......I am a believer in forcing the air through the radiator crowd. I have found over the years that making sure everything is good and tight, and the air seals are good will lower the temp significantly.

I also run Flowcool in my radiator. Might be a junk product for all I know, but it makes me feel better.

corvettesummer79

Im with ya Kdf ,Commander,Think its going to run a lot cooler now with the top rad seal on plus just retarded the timing a bit. The new fan clutch ought to help too. vettejim
both heater core hoses are valved off in warm months. didn't know that made it warmer.
sstocker thanks a new rad would be nice too much work and money. not until this one leaks

7T1vette

If it still runs hot and the inside of your radiator tubes are limed-up, you will have to use radiator CLEANER to get rid of the lime deposits; radiator flush will clean out old antifreeze 'gunk', but it won't do anything to remove deposits. Follow directions on the jug of cleaner and it will work well.

corvettesummer79

Thank you 7t1

tomgallucci57

ive been chasing an overheating problem for 5 years now.yesterday i decided it was time to change the heater hoses. mines a 1968,,so i remove the 2 plates from under the car that are under the heater core area. and low and behold what i saw was good and bad.the good part is that i see 3/4 in. hose is crimped or folded over like a garden hose that wont squirt much..i really really believe ive found my problem.im in the process of putting them on right now.they are made by gates-called shape-n fit-there coiled in a wire,then has a larger wire running down the lenght of it.so you can bend the hell out of them and not kink them...i would say anyone with overheating issues should take the time to check there hoses at the heater core for bends in the hoses.these old hoses im removing were not the correct style with pre-bent ends..best of luck tom, in cleveland,ohio

jb78L-82

I chased a hot running 78 L-82 for 25 years.. the later year L-82's run 225 normally and 235-240 in very hot weather with the AC going which is the temp mine ran for years. I tried everything and made sure every single factory piece was correct as many have mentioned. The only change that finally solved the problem permanently was a Dewitts aluminum radiator AND a Stewart Stage 2 aluminum water pump..The old L-82 engine never went over 180 degrees with this setup and the "new" L-82 engine has trouble getting to 175 degrees with 125-150 MORE NET HP over stock.

BTW-The radiator cap only pressurizes the system and will not change the temperature that the actual water/coolant runs but will change the boiling point of water to a higher temp-15 lbs pressure raises the boiling point of water to close to 250 degrees….Coolant added to water raises the boiling point even higher, lowers the freezing point dramatically and prevents rust in the system.

Kacyc3

you have a cooling problem somewhere. My 11:1 406 cools to 170 degrees running down the interstate, sitting in traffic the electric fans turn on and off with uncoated headers and the seal from my core support to hood is sitting in my tool box waiting to be put on.

69Vett

a blocked heater hose will not cause your car to overheat,
gm installed a vacuum control valve to do exactly that.

If you system is working properly, and radiator has properly cleaned, and correct calibrated sending unit,
your base warmed up temperature should be right at the temp of the Thermostat,
if its higher something is not functioning correctly.

If your using a 40 year old radiator, and have not cleaned it internally, that's a problem.