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I installed a coolant overflow tank on my 72 Cutlass. It seems like the tank has two plugs (I assume one for overflow and one for a return, but the OEM radiator doesn't have a return function.)
Should I leave it as is, or plug up the 2nd plug to seal the system off?
I installed a coolant overflow tank on my 72 Cutlass. It seems like the tank has two plugs (I assume one for overflow and one for a return, but the OEM radiator doesn't have a return function.)
Should I leave it as is, or plug up the 2nd plug to seal the system off?
One port is for the outlet from the radiator. The other is an overflow that dumps on the ground if the overflow tank, ah, overflows. Under the cap there should be one port that has a tube that goes to the bottom of the tank. That's the one that connects to the radiator overflow. The other gets a hose that just dumps on the ground. If your radiator overflows, coolant flows out the cap into the overflow tank. Once the radiator cools, the suction pulls the coolant back in through the same hose.
I would put a length of hose on it and route it down toward the ground.
Yes. There is a hole in the fender well area below the tank where the overflow hose can be routed so it drains onto the ground and not into the engine compartment,
Another alternative is a cap barely on it. Many overflow bottles have no drain. You're not going to overflow it with the proper level of coolant except in a boil over situation, and I would submit that you would have worse problems in that situation than a lack of drain hose would cause. Ideally, the overflow bottle will be @20% (i.e. "a little") of total volume full when the engine is cold and the radiator will be full. The bottle should get to be "mostly full" under the hottest of normal operating conditions.
One port is for the outlet from the radiator. The other is an overflow that dumps on the ground if the overflow tank, ah, overflows. Under the cap there should be one port that has a tube that goes to the bottom of the tank. That's the one that connects to the radiator overflow. The other gets a hose that just dumps on the ground. If your radiator overflows, coolant flows out the cap into the overflow tank. Once the radiator cools, the suction pulls the coolant back in through the same hose.
Interesting. I bought the OPGI OEM replica, so I guess the original overflow tanks were to just 'catch' spilled over coolant in the case of an overheating situation. There are just two ports on the top of the tank (pictured above), and there is no port/hole/tube/etc. on the bottom of this tank to pull coolant back into the radiator when the engine cools (like modern cars.) That's too bad.
Originally Posted by RandyS
That is more than likely a drain for an overfill situation. I would put a length of hose on it and route it down toward the ground.
This I can easily do, thank you!
Originally Posted by Fun71
Yes. There is a hole in the fender well area below the tank where the overflow hose can be routed so it drains onto the ground and not into the engine compartment,
Much appreciated, thanks!
Originally Posted by Koda
Another alternative is a cap barely on it. Many overflow bottles have no drain. You're not going to overflow it with the proper level of coolant except in a boil over situation, and I would submit that you would have worse problems in that situation than a lack of drain hose would cause. Ideally, the overflow bottle will be @20% (i.e. "a little") of total volume full when the engine is cold and the radiator will be full. The bottle should get to be "mostly full" under the hottest of normal operating conditions.
Thank you.
Originally Posted by Ozzie
I'm assuming that you also added a "recovery" type cap for the radiator so the coolant will return to the radiator as it cools.
I did.
Originally Posted by JohnnyBs68S
Isn't that what the "Closed System - Do Not Open" means on his cap?
Interesting. I bought the OPGI OEM replica, so I guess the original overflow tanks were to just 'catch' spilled over coolant in the case of an overheating situation. There are just two ports on the top of the tank (pictured above), and there is no port/hole/tube/etc. on the bottom of this tank to pull coolant back into the radiator when the engine cools (like modern cars.) That's too bad.
There should be an internal tube from one of the two ports in the cap that runs down to the bottom of the tank, just like in the windshield washer tank. This allows coolant in the tank to be sucked back into the radiator.
There should be an internal tube from one of the two ports in the cap that runs down to the bottom of the tank, just like in the windshield washer tank. This allows coolant in the tank to be sucked back into the radiator.
Good to know... Ahould I reach out to OPGI as this part never came with the tank?
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
Not necessary. Just hook up a clear plastic hose to the cap. Make sure it goes almost to the bottom of the reservoir.
This is an OEM NOS reservoir; it has all the numbers, markings, part number and fill level on both sides. It came with mounting brackets for A,B/C body cars.
Notice the mounting tab holes are properly centered, and the cap is solid color instead of translucent plastic?
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
Downspout hose - use black rubber. Clear hose for the reservoir - take the cap with you and go to an auto store or harbor freight. I believe they sell clear tubing by the foot. If you can't get clear - go with black hose. Not like anyone is going to look in there to see what color it is.
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
Yes. It will purge and fill according to the temperature of the coolant and effectiveness of the rad cap. Much like the coolant reservoir's in new cars. You've just created a closed system for your cooling so it shouldn't puke anything onto the ground during the summer or hot driving conditions now.
Yes. It will purge and fill according to the temperature of the coolant and effectiveness of the rad cap. Much like the coolant reservoir's in new cars. You've just created a closed system for your cooling so it shouldn't puke anything onto the ground during the summer or hot driving conditions now.
Thanks Alan. I just wasnt sure if I needed to put coolant in the overflow since I think I now have the radiator at the correct level.
What is "the correct level" that you have in the radiator? A closed system (one with an overflow tank) should have the radiator filled completely to the top, then more coolant in the overflow tank. This ensures there is no air at all in the cooling system.
What is "the correct level" that you have in the radiator? A closed system (one with an overflow tank) should have the radiator filled completely to the top, then more coolant in the overflow tank. This ensures there is no air at all in the cooling system.
Got it Kenneth. Thanks so much!
Last edited by Will22; April 10th, 2019 at 05:26 AM.
August 26th, 2018, 11:37 AM
