1969 Radiator Overflow tank applications.

[John M.]

I'm still waiting for my AIM and other books to come in so hopefully everyone won't mind some rookie questions for a bit.

I'm laying out all the parts i need to order for restoration and was surprised not only to not see an overflow tank on my car, but no holes in the inner fender to accomidate it.

Did the application of the overflow tank depend on Aluminum or copper radiator, or have I had some extensive body panel replacement I'm yet unaware of.

It appears I'm set-up with the copper radiator and have a very late (last day of production) 69.

Thanks in advance.

[Michael W.]

Re: 1969 Radiator Overflow tank applications.

No Corvette prior to 1973 had an overflow tank. What you're thinking of is an 'expansion tank'. They look similar, but perform very different functions.

All Corvettes prior to 1973 had an expansion tank, either internal or external to the radiator. Typically copper/brass radiators had a cap on them meaning that the expansion tank was internal whereas aluminum radiators with no cap required an external tank. The external expansion tanks (sometimes called a surge tank), are usually located in the passenger side inner fender well and are made of brass or aluminum being that they form part of the pressurized coolant system.

All pre-73 cars were dependant on having a controlled volume of air on the pressure side of the system, usually located beneath the radiator cap. As the coolant expanded with increased engine temperature the pressure inside the system followed suit. Any pressure exceeding the rating of the cap was expelled as air, not coolant. An overfilled system would 'puke' excess coolant on the ground as a result.

The 73 and up cars have no internal or external expansion tanks. Instead, the radiators are filled to the brim and excess coolant is routed to a non-pressurised overflow (or coolant recovery) tank, if and when the system pressure exceeds the rating of the cap. The coolant remain trapped in the tank and is later drawn back into the radiator when the engine cools and pressure decreases.

If you have a copper/brass radiator with a cap on it, this might be the correct set up for your particular engine option.

[John M.]

Re: 1969 Radiator Overflow tank applications.

Thanks Michael.

I'm assuming since there are no holes on the inner fender, and it appears to be a pretty original car with an all original drive train, that it's correct.

Is there any easy way to see the difference between the core supports or other tell tale signs of an original copper radiator factory installation?

[John C.]

Re: 1969 Radiator Overflow tank applications.

John

The use of copper vs Aluminum radiators in 69 was dependent on engine, transmission, and AC options. This also affected if the car recieved an expansion tank or not.

We need to know what is your engine, transmission, and AC options are?

John

[Terry M.]

Re: 1969 Radiator Overflow tank applications.

Too many Johns here

Your 1969 350/350 (I had to look at your public profile to find that information) is not supposed to have an expansion (surge) tank. When you get the TIM&JG you will find that it is (in most cases) supposed to have a copper/brass radiator. There are some folks who have indicated some 350/350 came with aluminum radiators, but I am not among those. As you become more familiar with your car, and explore similar Corvettes, you will soon be able to judge whether the equipment on your car "looks" original or not.

Join a local chapter and bring your car out for the judges to look at. They will show you how to tell these kinds of details.

The configuration of the cooling system on early C3 Corvettes depended on the engine size (both cubic inches AND horsepower) and whether the car had C60 (Air Conditioning) and sometimes the type of transmission installed.

[John M.]

Re: 1969 Radiator Overflow tank applications.

Yes sorry,

L46, M-21, 4:11 rear and void of options other than what I just listed.

Also a very late (18th to last) 69 produced (if that has any bearing)

It appears to have an original Harrison radiator and GM shroud (3956109) so it appears to be the correct set-up.

Kind of dissapointing as the Expansion tank is a nice engine bay detail.

This is my 3rd 69/70 Vette over the years. My 69 427/390 and 70 base Vert both had them so it threw me a bit.


Thanks for all your help.

[Joe L.]

Re: 1969 Radiator Overflow tank applications.

Yes sorry,

L46, M-21, 4:11 rear and void of options other than what I just listed.

Also a very late (18th to last) 69 produced (if that has any bearing)

It appears to have an original Harrison radiator and GM shroud (3956109) so it appears to be the correct set-up.

Kind of dissapointing as the Expansion tank is a nice engine bay detail.

This is my 3rd 69/70 Vette over the years. My 69 427/390 and 70 base Vert both had them so it threw me a bit.


Thanks for all your help.

John-----


As Terry mentioned, most 1969's with L-46 used a copper-brass radiator with NO external supply tank. In fact, the correct radiator for your application has no provisions for an external supply tank so you couldn't use one if you wanted to.

Some 1969 L-46's did use an external supply tank, though. I believe this was limited to early cars. I have a friend that's the original owner of his 1969 L-46. His car was built very early in the model year and it was originally equipped with an aluminum radiator with external supply tank. It lost its original radiator years ago, though, due to his lack of maintenance, and replaced it with a "hokey" copper-brass replacement unit. It still has the original supply tank, though.