correct level of coolant in the overflow tank for a '72 454?

[Randall K.]

I flushed and refilled my coolant not too long ago. I probably had some air bubbles initially, but I think they're all gone now. I have been refilling the overflow tank and then watching coolant come out of the overflow hose when hot. Engine temp seems to be stable during driving.

What is the right level of coolant that I should be seeing in the overflow tank when the engine is cold??

Thanks
Randy

[Dick W.]

Re: correct level of coolant in the overflow tank for a '72 454?

I flushed and refilled my coolant not too long ago. I probably had some air bubbles initially, but I think they're all gone now. I have been refilling the overflow tank and then watching coolant come out of the overflow hose when hot. Engine temp seems to be stable during driving.

What is the right level of coolant that I should be seeing in the overflow tank when the engine is cold??

Thanks
Randy

Finally gave up on keeping water in the tank, continually pushed out. Just watch temp guage and go.. I know that is going to get me flamed, but facts are facts.

[Terry M.]

Re: correct level of coolant in the overflow tank for a '72 454?

Not ever having a big block in a Corvette (well, not a real iron one anyway) I am free to ask really dumb questions. Does the owner's manual not tell you something about the coolant level? I confess to never having looked for that in the owner's manual. My small block has a mark on the passenger side radiator tank that says "FILL LEVEL." That makes it easy, even for us dummies.

BTW: I have heard BB owners beef about coolant burping on the ground for over 30 years.

[Dick W.]

Re: correct level of coolant in the overflow tank for a '72 454?

Not ever having a big block in a Corvette (well, not a real iron one anyway) I am free to ask really dumb questions. Does the owner's manual not tell you something about the coolant level? I confess to never having looked for that in the owner's manual. My small block has a mark on the passenger side radiator tank that says "FILL LEVEL." That makes it easy, even for us dummies.

BTW: I have heard BB owners beef about coolant burping on the ground for over 30 years.

The BB has a level line on the tank, I dare anyone that drives one hard and with the A/C on to keep it at that level.

[Mark H.]

Re: correct level of coolant in the overflow tank for a '72 454?

This may be some help re: coolant overflow and coolant recovery tanks. Mark http://homepages.donobi.net/sufuelpu...YSTEMS_AND.pdf

[Thad L.]

Re: correct level of coolant in the overflow tank for a '72 454?

I own a 70BB with A/C. Top off the tank, go drive and get up to temp. Park and watch it puke out what it dosent want. Forget about it

[Joe L.]

Re: correct level of coolant in the overflow tank for a '72 454?

I flushed and refilled my coolant not too long ago. I probably had some air bubbles initially, but I think they're all gone now. I have been refilling the overflow tank and then watching coolant come out of the overflow hose when hot. Engine temp seems to be stable during driving.

What is the right level of coolant that I should be seeing in the overflow tank when the engine is cold??

Thanks
Randy

Randy------


The correct level is about half full. Will you have to top it off regularly? Yes, you will. No pre-1973 Corvette was ever originally equipped with a coolant recovery tank so regular topping off is necessary. GM didn't add a coolant recovery system to 1973 and later Corvettes because things worked just as well without it.

[Edward J.]

Re: correct level of coolant in the overflow tank for a '72 454?

I flushed and refilled my coolant not too long ago. I probably had some air bubbles initially, but I think they're all gone now. I have been refilling the overflow tank and then watching coolant come out of the overflow hose when hot. Engine temp seems to be stable during driving.

What is the right level of coolant that I should be seeing in the overflow tank when the engine is cold??

Thanks
Randy

Randy, I would only put enough in the overflow to cover about 2 or 3 inchs off the bottom. this will at least let you know that the the level in the radiator is up. As everyone here has let you know what happens when the levels to high.

[Monte M.]

Re: correct level of coolant in the overflow tank for a '72 454?

Terry,
In answer to your burping question, YES, it just becomes part of what you get used to.

This is just normal driving where the little burping goes on.

On warmer days or on longer rides, if you just shut it off without giving them a few minutes to cool off, you get really used to adding coolant every stop. But, if you do take the time to ease up on them a bit before getting off the freeway or long stretch, just easing up for a while first will keep the burping to burping and not throwing up allover you.

Monte

[Michael W.]

Re: correct level of coolant in the overflow tank for a '72 454?

Or as Dick and others say, let it find it's own level and forget it.

[Bill C.]

Re: correct level of coolant in the overflow tank for a '72 454?

well --

think it is important to distinguish that the tank is really an expansion tank, not over-flow - two different beasts..

On my 72 I would fill it up maybe an inch or so --
Then run the car, let the air bubbles work their way out.
let it sit long enough to let the pressure down and take the cap off and see the level.
You be surprised - but it rose nearly to the top.

expansion tank......

always check levels when fluid is hot enough to keep thermostat completely open.

my 2 cents -- it worked for me.. :-)

[Joe L.]

Re: correct level of coolant in the overflow tank for a '72 454?

As far as C2 and C3 Corvettes go, radiator EXTERNAL supply tanks were only used on all 1963-67 small blocks, some 68-72 small blocks, all 1967-69 L-88, and all 1969-72 big blocks. In the case of the 63-67 small blocks, some 68-72 small blocks, all 67-69 L-88 (except 1969 with THM), and 1971 LS-6 (except THM), the external supply tank is the only tank the radiator has. These applications use an aluminum radiator without integral tanks of any kind. So, if you run the external supply tank dry, you have no way of knowing (and no expectation) that the radiator is full.

It's a bit different for 1969-72 big blocks (except L-88 and LS-6 with 4 speed transmission). These applications use an external supply tank in conjunction with a copper/brass radiator with integral supply tanks. So, in these applications if the external supply tank is dry one can still have an adequate level in the radiator for awhile supported by the integral supply tanks. Nevertheless, when the external supply tank is dry, one does not know what the level in the integral supply tanks is since there's no filler on these radiators to inspect the level in the tanks.

The above is why I do not recommend running with a dry external supply tank.

[Paul O.]

Re: correct level of coolant in the overflow tank for a '72 454?

One other problem could be if your are using a reproduction radiator cap these are know not to be as accurate holding the design pressure as original AC Delco caps.

[Dick W.]

Re: correct level of coolant in the overflow tank for a '72 454?

One other problem could be if your are using a reproduction radiator cap these are know not to be as accurate holding the design pressure as original AC Delco caps.

A 20# cap MIGHT keep it from puking, but very doubtful. It is the nature of the beast