Fluid in overflow tank goes back into radiator ??

[Racer57]

Never gave this much thought before. Ive always understood that the hot engine coolant that goes into a overflow tank will go back into the radiator as engine cools down. How is this possible with a radiator cap ?

[tman]

This may help

https://www.coolcatcorp.com/Radiator%20Caps/Radiatorcaps.html

[anlauto]

There's two types of caps for either an open system that just spits it on the ground, or a closed system that draws it back from a reservoir

[Racer57]

Thanks ! 

[YellowThumper]

Proper cap has an internal relief valve that opens when system cools and creates a suction.

[cuda hunter]

Can someone verify the actual part number for the 70 overflow tank?
I can't seem to find it in the parts book.

[tman]

Can someone verify the actual part number for the 70 overflow tank?
I can't seem to find it in the parts book.

You will not find one.  They were available for 73-74 I believe.  But they should fit earlier models

https://dantesparts.com/i-30499142-mopar-coolant-overflow-bottle-1973-1974-e-body.html

There are alternatives.  You can find some aftermarket one to work.  What I did on my 70 was convert my windshield washer reservoir into a coolant reservoir.  Pretty ez to do and mine works just like the factory ones. 

[Ebody Edgar]

The best cap for a system with an overflow tank is Chrysler cap 3781830 [partial-pressure cap]; plenty of those all over eBay. It supersedes to 52079880AA if you want one from the dealer. Watch out for chineese knockoffs.

[YellowThumper]

My 74 came with this that mounted to bracket that mounted via radiator mount bolts.

[Racer57]

My 74 came with this that mounted to bracket that mounted via radiator mount bolts.

Thats exactly what I have. But it will not fit. Where the shroud fastens to the radiator is in the way and prevents the overflow bracket from fitting. I'm guessing my Cuda doesn't have the correct radiator for the overflow bracket/jug.

[MoparLeo]

Coolant recovery systems and an overflow are not the same thing.
The recovery system uses the 2 way radiator cap that allows coolant to flow out when hot and back in when the coolant cools and creates a vacuum in the system that draws the coolant back in.
They became standard in 1973 along with other safety and emission changes.
An overflow just catches the heated coolant instead of letting drain onto the street.
Overflows are required if you want to run your car at the dragstrip for obvious safety reasons.

[YellowThumper]

My 74 came with this that mounted to bracket that mounted via radiator mount bolts.

Thats exactly what I have. But it will not fit. Where the shroud fastens to the radiator is in the way and prevents the overflow bracket from fitting. I'm guessing my Cuda doesn't have the correct radiator for the overflow bracket/jug.

Interesting there is interference.
Bracket extends a long way outward from core support for where bottle mounts.

[Racer57]

My 74 came with this that mounted to bracket that mounted via radiator mount bolts.

Thats exactly what I have. But it will not fit. Where the shroud fastens to the radiator is in the way and prevents the overflow bracket from fitting. I'm guessing my Cuda doesn't have the correct radiator for the overflow bracket/jug.

Interesting there is interference.
Bracket extends a long way outward from core support for where bottle mounts.

The bracket extends to the side (towards battery) only about 1/2 the distance required to clear the shroud. I suspect I do not have a factory radiator/shroud.