Is the radiator overflow tank needed?

GLAMIS WEATHER
JM PRO

JM PRO

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I am currently in the middle of a rail remodel and having a tough time with packaging. The radiator is mounted high on the x brace above the engine. I can mount the overflow tank down low by the mid rail on the opposing side of the radiator cap. The overflow tank will be 2-3' below the cap and 5' away. My guess would be 10' of hose. My 2 cents is it will not work, I would need to mount it higher and closer to the level of the cap.


I can build a custom tank and mount it higher but this process got me thinking, has anyone not run an overflow tank and not had a problem?

Thanks
 
With heat you get expansion. With cooling you get contraction. Having a radiator cap that is designed for a recovery tank setup will allow the coolant to flow to the overflow and keep the level topped off in the radiator. On cool down, the radiator cap will allow the coolant in the overflow to be sucked back into the radiator.
Having the overflow tank low or father away won't matter but may take a few heat cycles to fill that hose and set it's cold and hot level.
We have the same situation in the motor yachts we work on. Works fine. If anything same height or lower is preferred. If the overflow was higher than the radiator cap, it would drain out and overflow the radiator when the radiator cap was loosened or removed.
Get the rated pressure cap you need and get one that works with an overflow tank. Usually identified with a rubber seal under the cap plus the regular one on the spring seat.
 
Went through this same decision process on my current project as I couldn't find a spot above the radiator cap that i liked...and learned there's a lot if mixed answers on the topic, but more leaned towards it's OK to have the overflow tank below the radiator as long as it has vented cap OR if there's an open overflow line built into the overflow tank.
 
You are probably going to need it. But, I remember when cars and trucks didn't have them.
 
Yes,
The Radiator cap is more like a thermostat, it has a double acting spring, it is not a spring loaded cap,
It will always be low on water if you don't have a overflow tank,

My overflow tank is mounted near the side of the trasaxle,
the hose is to the bottom of the overflow tank, so it does not matter where the tank is mounted, it works like a straw sucking from the bottom of the tank
 
IMO it is just as important a part of the cooling system as the radiator cap & water pump. it dont gotta be fancy, just gotta be there.
 
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