Coolant Overflow Tank

MJFUR

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Is this an original Mopar part or not? I can't find any Part #'s on it. It was added on to my 69 Chrysler 300 which doesn't require one. If it's after market I'll just toss it. Thx

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CBODY67

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The key to making these things "work" seems to be where they are mounted, it seems to me. They need to be very close to the radiator and elevated such that the lines are pretty much at the level of the radiator's filler neck. PLUS a radiator cap "rated" to be for a coolant recovery vehicle. By observation, the best-located aftermarket tanks did not work as well as a factory-configured system.

On the other hand, a necessity for a drag strip raced vehicle. Where it might be considered "a catch can" of sorts.
 

Gerald Morris

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Looks near identical to one I got from NAPA the past Spring. Mine works very well. Mind you, I still check the fluid level in the radiator top tank to insure its at the level specified in the FSM:1.25" below the filler neck seat. I've found that more than this doesn't permit enough room in the tank for proper cooling, and sure enough, the temperature can go up 10 degrees or more.

With the right coolant level, I get a presence of just a few table spoons in that overflow tank when the engine is cool. But when parking briefly after running in hot traffic, it does catch a bit, which then gets sucked back into the radiator as the coolant contracts. My system maintains excellent equilibrium.

Put the tank next to the radiator, with the cap at the same height as the radiator cap, run the overflow to the bottom of the tank, and all should be well.
 

MJFUR

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Looks near identical to one I got from NAPA the past Spring. Mine works very well. Mind you, I still check the fluid level in the radiator top tank to insure its at the level specified in the FSM:1.25" below the filler neck seat. I've found that more than this doesn't permit enough room in the tank for proper cooling, and sure enough, the temperature can go up 10 degrees or more.

With the right coolant level, I get a presence of just a few table spoons in that overflow tank when the engine is cool. But when parking briefly after running in hot traffic, it does catch a bit, which then gets sucked back into the radiator as the coolant contracts. My system maintains excellent equilibrium.

Put the tank next to the radiator, with the cap at the same height as the radiator cap, run the overflow to the bottom of the tank, and all should be well.
My car was designed to run without one. A properly setup car doesn't puke fluid out. I drive around in 100F+ heat without any problems. Fluid level in rad is at proper level.
Part is gone. Thx
 

Gerald Morris

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My car was designed to run without one. A properly setup car doesn't puke fluid out. I drive around in 100F+ heat without any problems. Fluid level in rad is at proper level.
Part is gone. Thx

XLNT! I admit it seems excessive to use an overflow tank given how the same 2 tablespoons of coolant sit at the bottom of the little one I have for weeks at a time, but after enduring my Ordeal of Fall 2021, I got happy with cooling system accoutrements a bit. You're 1000% right on about not needing them for a well designed cooling system of course.
 

MJFUR

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Additional coolant isn't needed. It cools just fine with the factory recommended 18 qts.
 

Big_John

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yes lets use a reduced amount coolant because the factory was too cheap to use one
The reason they started using overflow tanks was the operating temperature of the engines was increased do to the smog requirements. Leaner mixtures, catalytic convertors, retarded timing etc. all lend to increased heat. They also started using "hotter" thermostats to get the engine temperature up for emissions reduction.

All lead to using the closed system we have now. Back in 69, they didn't need to run a closed system. I can't think of a single car that had a closed system before 1970 (ish).

While the "factory" did a lot of stuff to save costs, this wasn't one of them.
 
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