1978 overheating

[ilangford]

I am a proud new owner of a 25th Edition '78 (my first vette!) Straight to the problem... overheating! 350 cu.in. w/auto and a/c... gauge reads 210+ after long idle w/ a/c running. (has boiled over twice) No problem if a/c is not running. Has a Modine radiator 19 - 2890717 (tag number) I know it is not original radiator... looks too narrow, slightly less than 2" deep. I have been unable to find out if this is the correct radiator for this vette. This vette originally sold in Canada and has been up north its entire life. Just can't seem to take these hot Texas summers! Has 7 blade clutch fan, shroud in tact, replaced t/stat. I don't mind investing in a new radiator, but I first want to know if that is the likely source of the problem. Help!

[fatherlarry]

Welcome aboard!

Good luck with your new purchase.

You didn't mention what the mileage is on the Vette. As you know, it could be a number of things. It could be a clogged radiator, which they're known for. The factory radiator is still available from GM. Or you can go to your local radiator repair shop and they could sell you a heavy duty unit that will work just as well as the factory and look the same as factory.

Or, it could be a bad thermostat, even though it's new. Or, the clutch on the fan could be bad. Or, the fan may have been replaced with an aftermarket one that isn't correct for your car. You could also have clogged water passages around head gasket or the system may be air bound. These cars do tend to run hot, especially with the A/C running. Check to see if you're losing any water, because if you are, it could be a bad water pump. Check each item I mentioned, and through process of elimination you will hopefully find it. I'm going with the thought that it's the radiator or clutch attached to the fan. Good luck and let us know how you make out. Let's see some pics.;bt :usaribbon :shift:

[ilangford]

I got a reply back from Modine... the replacement radiator installed by prior owner is not for vette's with a/c! Any recommendation on new radiator? Tom Benford, in his book Performance Projects recommends a "all aluminum direct fit racing unit from Dewitts. I would like other opinions before making this purchase. Thanks again.

[fatherlarry]

Depending on what type of driving you're going to do, and how much money you want to spend, I feel, that what the gentleman recommended to you may be a little bit of overkill for a street use Vette. However, here are some options you may also want to look into, depending on the type of driving you plan on doing.

1) Stock radiator (one for that year which supports A/C)
2) A heavy duty triple core radiator supplied by a radiator shop in your area.
3) A stock radiator with the option of installing dual electric fans, which works very well and are affordable.

I personally would go with a triple core radiator. It looks original, has more cooling blades and has more cooling ribs which are larger. I would stay with the stock clutch and make sure the cooling fans have the same amount of blades that came with the correct original stock unit. Good luck.

[FinWolf]

this is great reading and he makes great radiator

www.dewitts.com/download/cooling.pdf

[fatherlarry]

Great job FinWolf ;bt

[FinWolf]

Originally posted by fatherlarry
Great job FinWolf ;bt

you know me i dont do much but what i do is the best.:LOL: :LOL: :LOL: :LOL:

[DavisZR1]

Finwolf,

Especially when it comes to eating cheesesteaks and cannoli's.

:rolllaugh

[FinWolf]

Originally posted by DavisZR1
Finwolf,

Especially when it comes to eating cheesesteaks and cannoli's.

:rolllaugh

I do that even better eating is my best sport.:LOL: :LOL: :LOL:

[DavisZR1]

What :dunno:

[ilangford]

hey guys,
back to my radiator problems... would a 4 coil core be any better than a 3 coil core?

[FinWolf]

I would say yes the more the better. did the rest of the system check out ok. there is a product it is called 40 below i think it is called that. you add it to a 50/50 mix. it is better then water wetter. because it is made to be used with antifreeze. it will bring your temp down 25 degrees im going to try it as soon as i can find it. I use water wetter now.

[pbcanney]

I can't add anything to the overheating issue, but I can add that the 78 is the best looking C3 in my estimation. It just flows so well from bumper to bumper.

Good choice. and good luck with the radiator. Obviously, it's in better hands now.