....... you dealt with the problem?

Having the overflow go out to the ground is a real pain, and a waste of fluids.

Show what you've done to create a closed system.

:)

There's a lot of ways to attack this often discussed subject. You might try a search for "overflow" in heating and cooling.

One very popular method is to run a hose across under the front lip of the rad support and use the washer bottle.

Also, if you only fill (when cold) to the "fill cold" mark cast into the pass side rad tank (it's nearly 6" down from the top) the system will typically not puke fluid.

I use the factory plastic overflow reservoir from an early 70's Nova/BOP donor. It mounts behind the battery; under the fender, on top of the wheel housing and behind the passenger side headlight. I also use the factory overflow hose and clamps to give it that OEM look. I have done this on all my pre 1970 units.

I have used the method Jim suggested, works fine. I also set it to the level Jim suggested and it has never once puked.

The only reason I set up an overflow was due to the restrictions when running it at the track. Tech inspect wanted to see some kind of overflow setup.

I have found about 2" down with the top with the core tubes just exposed works well. Since this is room for liquid expansion altitude may play a big part in how much room you leave.

I'd like to throw in a word of caution for those using dexcool to protect their alum heads, radiators and blocks from corrosion. It requires no air in the system so a modern overflow that purges when hot and sucks the fluid back into the rad when it cools is required...

Thanks for the replys. I guess i need to learn how to use these forums better. Took me 20 minutes to find this thread, which i originally posted in the "Camaro Tech" forum.

I still am having trouble figuring out where the sub category's are :(

edited to add: i had a main page link set up for the 'short' version of this site :oops:
all fixed now :)

I keep my coolant an inch or two low and don't have problems with it spilling out. I don't think a coolant overflow tank is necessary.

Thanks for the replys. I guess i need to learn how to use these forums better. Took me 20 minutes to find this thread, which i originally posted in the "Camaro Tech" forum.

I still am having trouble figuring out where the sub category's are :(

edited to add: i had a main page link set up for the 'short' version of this site :oops:
all fixed now :)

Hey Doug - Camaro Tech is kind of a catch all forum when someone doesn't know what forum to post a question in. Several mods and the admins have the ability to move threads from Camaro Tech to more appropriate forums. This thread was a perfect example. It fits perfectly in Heating and Cooling where Radiator and cooling systems are discussed.

There is no implication placed on the poster when a thread gets moved, it's just house keeping. The best way to find a thread you have posted in is to click on the "User CP" link upper left on the second red horizontal bar. There will be an area showing "New Subscribed Threads" with links to them. If what you want is not on the list look at the bottom of the list on the right for another link that says "View all Subscribed Threads" click that and all the threads you have posted in will be listed... I use this all the time, it works great. :beers:

Hey Doug - Camaro Tech is kind of a catch all forum when someone doesn't know what forum to post a question in. Several mods and the admins have the ability to move threads from Camaro Tech to more appropriate forums. This thread was a perfect example. It fits perfectly in Heating and Cooling where Radiator and cooling systems are discussed.

There is no implication placed on the poster when a thread gets moved, it's just house keeping. The best way to find a thread you have posted in is to click on the "User CP" link upper left on the second red horizontal bar. There will be an area showing "New Subscribed Threads" with links to them. If what you want is not on the list look at the bottom of the list on the right for another link that says "View all Subscribed Threads" click that and all the threads you have posted in will be listed... I use this all the time, it works great. :beers:

Thanks Dennis,
:cool:

Thanks for the helpful suggestions.

I set up an overflow system this last weekend using a generic container available from most parts stores. (found mine at Walmart) Since i converted over to an internally regulated alternator i was able to remove the external voltage regulator from the drivers side radiator support. This opens up/leaves a perfect space for the overflow container and bracket. It seems to work fine. (at least in the weather we're having here in Oregon currently. Summer will be the real test)

The reason i was hesitant on the 'underfill' idea was my understanding that air in the cooling system can be a bad thing.

My line of thinking is this:
Keeping the coolant level low in the radiator can cause air bubbles in the system. Air bubbles can result in cavitation in the water pump vanes, leading to premature failure.
That and the possibility of steam related pressures and 'pops' on the system.

Being new here i realize no one knows me yet, so please feel free to correct, and inform me, if my thinking is whack. I can take it ;) :beers:

... The reason i was hesitant on the 'underfill' idea was my understanding that air in the cooling system can be a bad thing.

My line of thinking is this:
Keeping the coolant level low in the radiator can cause air bubbles in the system. Air bubbles can result in cavitation in the water pump vanes, leading to premature failure.
That and the possibility of steam related pressures and 'pops' on the system.



The early systems were, for the most part*, designed to be 'self-purging' - meaning they would allow air to rise to the highest area of the sysetm (or radiator) so there wouldn't be a problem with air entrapment, as there can be with more modern cars with odd (read 'lower' than the highest point in the engine or system) radiator cap location.
Air entrapment in modern systems combined with many of the new "permanent" type antifreeze/coolants, like Dex-Cool types, require all the air be removed so it doesn't react with the coolant and cause problems with sludge build-up. This is why you find 'air-bleeds' or odd locations for the system fill cap on most of the newer vehicles.
If - you're using a more common "Green" (yes, I know some of the perm. types are also availble in green - but not most, yet ...) antifreezes then the amount of air that can be in the system is usually not an issue in causing sludge formation and other issues.

Cavitation of the pump impellers is a function of blade dynamics more than just air in the system. Any given impeller or propeller will cause some separation of air particals from a liquid stream at some given speed or rpm - that's just the natural of them.
Using a proper mixture of antifreeze/coolant, and maybe a small addition of one of the "water wetters" (just a surfactant), will usually give you the performance you need to allow the best cooling of any given system without worries about air or cavitation issues.

Hope this helps and others chime-in with anything I missed;
John

* = some Corvettes, Thunderbirds and others had systems designs that required special service procedures to remove trapped air.

Your thinking is not out of whack at all, except... until the 70's, no cars had overflow tanks, for many many years. Other than sometimes puking some coolant either due to overfilling or overheating, it was never a problem.

It's normal for the coolant to expand when it gets hot. When it expands it take up more space, which is what builds pressure in the cooling system. The rad cap has a pressure release valve to limit this pressure. When the relief valve opens, it will burp some air, or if there is no air, it will burp some coolant. It's all normal.

The sealed expansion tank system used in newer cars give the excess coolant someplace to go. Remember liquids are not compressible. If the rad is filled to the top, and what it's filled with expands 5%, some of that liquid has to go somewhere or the rad will just explode. The relief valve opens, bleeds the excess liquid into the expansion tank, and life is good. When the system cools off, it even draws the liquid back into the rad to take up the space left when the coolant gets "smaller" as it cools.

It's an excellent system, and worth retrofitting to our old cars, but it's not required (except at the race track).

... until the 70's, no cars had overflow tanks ...



We should never say all or "no" Jim - I'm sure we can all name exceptions to this ... ;)

You're old car buddy;
John

The overflow canister doesn't hurt anything and if it works as designed will have a cold and hot level with the hot being higher. Even if it doesn't work as designed by sucking the fluid back into the core it's still a catch can for when too much pressure builds up.

Older systems are not designed to need a catch can. Because of the direction of the fluid flow, the air gap at the top of the core will never find it's way to the water pump or into the block. That's not to say you can't get an air pocket trapped somewhere, it just won't come from the top of the core.

The fluid flows from the lower hose to the water pump, through the block and heads and out the intake manifold past the thermostat and back into the radiator through the upper hose.

The air gap is to allow for expansion as the fluid gets hot. Even then some pressure will build inside once the expansion of fluid takes place. The pressure cap keeps this under control and a maintained cooling system won't build more than the cap is rated at when the engine is running. Once you shut the engine off heat soak raised the fluid temp and builds more pressure. This is when a radiator that was filled to the brim when cool will puke.

If you ever go to the track you will be ahead of the game with what you have installed...

I use the factory plastic overflow reservoir from an early 70's Nova/BOP donor. It mounts behind the battery; under the fender, on top of the wheel housing and behind the passenger side headlight. I also use the factory overflow hose and clamps to give it that OEM look. I have done this on all my pre 1970 units.
Does anyone know whare in can get one of these new i have raided the local salvage yards for my last camaros.I have also looked at Classic ind
and cant seem to find one ?

Does anyone know whare in can get one of these new i have raided the local salvage yards for my last camaros.I have also looked at Classic ind
and cant seem to find one ?
I didn't worry about it because they were never available on first gens.
But the reason that this subject keeps coming up seems obvious to me; First gen systems didn't work well. Sorry. Been there.
My BBC holds SIX GALLONS of coolant. That means a lot of expansion and that means a lot of air to deal with it is needed. When GM released closed cooling on the 1970 Buick's and Cadillacs I went right to my favorite parts man and special ordered the stuff. It didn't look too good. I had to hang it from my drivers side support bar. Then I came up with the idea to move the battery to the trunk and that opened up that area for this. It's made by Moroso. A copy of a Moon tank and to some extent, Corvette tanks. P.S. The tank cap does nothing. The lower seals have been removed to allow air to exchange freely. The tank can't work as an expansion tank unless that's done.
http://epitomesrebuild.com/images/138.JPG

Does anyone know whare in can get one of these new i have raided the local salvage yards for my last camaros.I have also looked at Classic ind
and cant seem to find one ?

Classic used to carry them for the 74 - part #G8740 in an older cat.
Call them and ask.
You need to buy the cap and hoses seperately. You can find the cap at local dealers (maybe the tank to - never tried ...) or as a "HELP" part at some auto parts stores.

moroso has this beauty of a can part number 63660.. I fit it infront of the battery and behind the grill but beside the radiator so it doesnt block air flow it sits in there beautifully and really no one can see it even tho it isnt bad to look at it. this thing works great and is no maintenance.. It recirculates which is important in a overflow container some of them just hold the excess and doesnt recirculate back into the radiator.

I have it I love it!!

I didn't worry about it because they were never available on first gens.
But the reason that this subject keeps coming up seems obvious to me; First gen systems didn't work well. Sorry. Been there.

Fred - that's just your one experience... I drove 60's vehicles all through the 70's in all different weather except below zero cold stuff. Never had a problem with stock cooling systems in Ford and GM vehicles. None puked and most were well abused. Fast forward to modern times and both my 72 Nova and '69 Camaro without overflow or catch cans never spew and perform flawlessly... I go out every month with a dozen or more other Camaro nuts on cruises and none have cooling problems or spew issues requiring an overflow.

The recovery systems came about because folks over filled the radiator and they puked and they over filled them again and they puked or the pressure caps went bad and they puked as they over heated. Back in the day was no different than today, people often just drive their cars and don't do preventative maintance until something breaks. Today most these vintage vehicles are coveted possesions owned by attentive caring people who pamper their classics often in an obsessive manor. As well there are very few classics on the road as opposed to the days of old...

Recovery systems are a good idea as they do protect the environment. They make some cool tanks and if you want one under your hood have at it. If you don't want to alter the stock engine compartment though don't feel pressured to as a proper maintained system isn't going to spew and leave a green puddle under your car...

Fred - I like what you've done under your hood with the mix of old school and modern. Very cool...