[irgoatmike]

My 67 gto overflows coolant after parking it from a 1/2 drive. Car is in the 210-215 range at shutdown and not acting like it's overheating but come out to a puddle on ground. These cars never had an overflow tank, but I think adding one would not hurt. Any opinions or input from folks who have done this on their car? Irgoatmike

[GT182]

Mike, how many pounds is the radiator cap set for? I just went to a 16# cap and no more overflow. No, I don't have an overflow tank on my 66. It would "mark it's territory" often but no more. Just an idea. Try it first and see what happens.

Edit:
I was told that the 16# cap will raise the boiling point a bit higher and help stop overflow.

[TedRamAirII]

Make sure its not "over filled", and that the cap is good. I suspect your cap is not holding pressure.

[Chris65LeMans]

Easy to do: mount a container, run a hose from the radiator to the can. Fill your radiator all the way up, then fill the can to just above the "min" line. (Mine expands quite a bit when warm.)

[irgoatmike]

I may have been overfilled, the cap is a 16 but sat dry for a long time. The cap would be an easy check thanks for tge tips. Irgoatmike

[rexs73gto]

When you check the amount of coolant in the rad. it should be about 1 inch down or what looks to be 1 inch low. If they get filled more then that it will overflow on the ground. These were made to look low in the rad. as the coolant does expand a lot when it gets hot & it needs to be that low in the rad. or it overflows if it's higher then that in the tank.

[Goatracer1]

The old radiators had a line on the tank indicating the full line. It was about 1 inch above the core on vertical cores. The cross flow type have a mark on the tank that the cap is on showing the full point. It is 4-5 inches down from the top. If you add an over flow tank you must change your cap to one for a radiator that has a tank. Your original one doesn't seal the cap to the top of the filler neck only seals the bottom of the cap to the radiator. If you don't change it the coolant will enter the tank but when the engine cools air will leak around the top of the cap and enter the radiator instead of the water in the tank returning.

[Geoff]

It would be a good idea to fit a recovery tank/bottle, not just an overflow bottle.
The RT allows the coolant to be drawn back into the engine when it cools down. In addition to the benefits already mentioned, it keeps air out of the system for better temp control.

[pontibeast]

I am adding a tank to my Lemans as well. What kind of cap do you need to get to switch to a recovery tank? Also is 16 pounds a good pressure for a moderately built 455? Thanks

[Geoff]

The recovery tank cap has an additional rubber seal & valve incorporated. You just need a 'recovery' tank cap, 13-16 psi, to suit your car.

[pontibeast]

Thanks, Geoff. I would prefer it to act as a recovery tank and not just an overflow.

[Chicagogoat]

Back in the day when I went to a higher capacity Griffin rad I converted to a simple Jegs alum recovery tank. With the overflow hose from the filler neck to the bottom of the tank, so the overflowed coolant draws back into the filler neck automatically. Then a top port you can run a hose towards the ground. There are hundreds of one's to chose from but no need to buy an expensive one. I saw a Be Cool one $160! A simple round or hex shape one(like Jegs) can mount neatly somewhere on the core support does the job

[Goatracer1]

If you want cheap and simple I just use a plastic windshield washer tank. Run the hose in the center of the cap and down to a 1/2 inch off the bottom of the tank.