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Expansion tank - makeshift installation instructions please?

dshanks

Well-known member
Joined
Oct 11, 2005
Messages
137
Location
KCMO
Corvette
1971 4spd coupe - Charcoal Gray
Hi all,
I just picked this up on ebay. The description states it came from a 66 vette. I know its not correct, but my car has been dropping glycol on the ground, and I caught my dog licking that stuff up one day.
Does anybody know how to hook this thing up. If needed, I could post detailed photos after I recieve the item. My vette is a 71, right now the overflow dumps right on the ground.

tank.jpg

any help is greatly appreciated!

Derrick
 
dshanks said:
Hi all,
I just picked this up on ebay. The description states it came from a 66 vette. I know its not correct, but my car has been dropping glycol on the ground, and I caught my dog licking that stuff up one day.
Does anybody know how to hook this thing up. If needed, I could post detailed photos after I recieve the item. My vette is a 71, right now the overflow dumps right on the ground.

http://www.dshanksdesign.com/images/tank.jpg
any help is greatly appreciated!

Derrick
that is not a overflow tank but a purge tank used on tankless rads to remove the air from the system. to use this on a regular system you connect the big bottom hose to the input of the water pump,replace the pressure cap on your rad with a regular cap and connect the over flow hose from the rad to the small fitting on the side of the tank. the new over flow hose connects to the cap bung on the tank next to the cap
 
Corvettes before 1973 did not have or need overflow tanks. As Clem (motorman) stated above, you've got an expansion or surge or purge tank meant for use with tankless radiators.

Wrong widget for what you want to achieve.

It's most likely that you are losing coolant simply from over filling the radiator.
 
dshanks said:
Hi all,
I just picked this up on ebay. The description states it came from a 66 vette. I know its not correct, but my car has been dropping glycol on the ground, and I caught my dog licking that stuff up one day.
Does anybody know how to hook this thing up. If needed, I could post detailed photos after I recieve the item. My vette is a 71, right now the overflow dumps right on the ground.


any help is greatly appreciated!

Derrick

All you need is a simple catch can,you can purchase a simple plastic on at auto zone and place it lower then the radiator overflow,and run the overflow hose to the catch can.

Antifreese and animals also scares me.
 
motorman said:
connect the big bottom hose to the input of the water pump,replace the pressure cap on your rad with a regular cap and connect the over flow hose from the rad to the small fitting on the side of the tank. the new over flow hose connects to the cap bung on the tank next to the cap

Thanks for the tip. Appreciate any help I can get!

Derrick
 
sharkcar71 said:
Just cap off the outlet on the bottom and use it for your overflow.It would look cool under the hood.

This is what I had in mind, just didnt know how to make it function properly. Wouldnt I need a return line that feeds from the bottom, so the pressure can push the coolant back into the radiator? wouldn't I want to cap one of the tubes on the top, and use the large outlet on the bottom for the return line?

I got this idea when I was at autozone, I saw a plastic tank. I thought to myself "this is what I need to keep the vette from dumping on the ground" but I also thought "but that thing is freakin ugly, and theres no way im putting that thing under the hood of my vette". Thats when I checked ebay and found this aluminum vette tank. I think it will look nice under the hood, and it appears to be in good shape, but with the "petina" that im looking for...
 
motorman said:
that is not a overflow tank but a purge tank used on tankless rads to remove the air from the system.

Can you please explain a tankless radiator, can it be as self explanitory as it sounds? Also, please explain the difference between a "catch can" or expansion tank and a surge/purge tank.
 
dshanks said:
Thanks for the tip. Appreciate any help I can get!

Derrick
i forgot you should put the pressure cap from the rad onto the tank
 
dshanks said:
Can you please explain a tankless radiator, can it be as self explanitory as it sounds? Also, please explain the difference between a "catch can" or expansion tank and a surge/purge tank.
Again, I'll state you've bought the wrong widget for the wrong purpose. Corvettes in good running condition and in stock configuration DO NOT need any additional gadgets to work properly. Your car should not be puking coolant on the ground unless you're overfilling it or there's a mechanical defect that needs to be corrected.

Corvettes from 1973 onwards only had overflow tanks (catch cans). An overflow tank is usually a ugly plastic container, and is always located on the NON pressurised side of the cooling system. Corvettes with coolant tanks also had no expansion tanks, either external or internal.

Corvettes prior to 1973 had either internal or external expansion tanks (surge/purge tanks) depending on radiator type and construction but not both. The widget you bought is an external tank and is intended for tankless radiators. Your original radiator (and I assume your present radiator) had internal expansion tanks. These expansion tanks were are always located on the pressurised side of the cooling system and are meant to be left partially empty when cold. There is a mark to indicate the MAXIMUM cold fill level.

Corvettes with expansion tanks work by allowing the air in the tanks to become pressurised as the engine warms up and the coolant expands. Under normal circumstances, the air pressure never reaches the point where the cap reaches it's pressure rating and opens to allow the excess pressure to bleed off. If the system is overfilled or there's a malfunction, the blow off point may be reached during operation and all the air and/or some of the coolant gets 'puked'. The puking as you have seen ends up on the floor and is a sign that's somethings not right.

Corvettes with overflow tanks have no provision to allow air space on the pressurised side of the system. This means that at each cycle where the engine reaches full operating temperature, the radiator cap will blow off at it's rated pressure. The excess coolant (or air that's accidently gotten into the system) will flow into the overflow tank via a hose.

As the engine cools after operation, the partial vacuum in the system will cause the radiator cap to open again and this time suck the same fluid back into the radiator, minus the air.

What you're trying to do is either add yet another expansion tank onto the pressurised side of the system (if you use the tank for it's original design purpose) or to turn the tank into an overflow tank on a system that's not set up for it.

Hope this helps.
 
Any information helps, and my list of questions about this is getting smaller. I mainly want this on my car as a safety precation because I have 3 dogs that have access to the garage. And I already know that female likes the taste (found this out the hard and expensive way)

The vette doesnt leak everytime I drive it, but it does overheat on occasion, and when this happens, its pretty violent and causes a huge mess.

My thoughts on why it overheats:
I think the heater core has a small leak, cause I can hear it hissing while it cools. I think the pressure slowly lets out my coolant. when the level gets lower and lower, the water gets hotter and hotter so the radiator has a harder time cooling the water. then when the level reaches a very low level, the water gets super heated and violently releases pressure onto the ground.

Does all this sound about right?

The radiator needs to be worked on, and the heater core will be inspected and replaced if needed. This should take care of the problem. In that case, I still want this tank to function as a secondary protection for my dogs, should the built-in overflow tank fail.

That being said, what would be a good way to hook this tank to my current system to perform this function. There were a couple installations outlined above, which does everybody agree would be the best to do this job?

So, might be the wrong gadget for this, but I have a good feeling that it will be suitable. Nothing wrong with a little down-home engineering on occasion, right?
 
That expansion tank simply isn't suitable for your intended use as an overflow tank - the inlet doesn't go all the way to the bottom of the tank (which is required in order to pull coolant back into the radiator), it's pressurized (unless you leave the cap off), the bottom outlet is WAY too large if you use it as an inlet, and it needs about $50.00 worth of brackets, rivets, straps, and bolts in order to mount it. I'd put it back on eBay (it's a service replacement for '63-'67's, made in August, 1988) and buy an overflow tank from Summit or Jeg's - they have lots of nice-looking tanks with the proper hose and mounts.

Longer-term, you should determine where the weak link is in your cooling system that's causing it to "puke" coolant.
:beer
 
dshanks said:
That being said, what would be a good way to hook this tank to my current system to perform this function. There were a couple installations outlined above, which does everybody agree would be the best to do this job?

I see where you're going, but as John says above this is the wrong tank. You're trying to put a square peg in a round hole. None of the suggested schemes will have it do what you would like.
 

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