[trshman]

Despite a PY Aluminum radiator; Flow Cooler pump and 160 degree thermostat, every now and then on hot days the radiator overflows. It's getting a little old carrying around a jug of distilled water and was wondering if anyone has ever used the windshield washer tank as an overflow reservoir and if so how that worked out. As an alternative, has anyone ever installed a separate tank in a car that didn't originally have one??
Mine is a '66 LeMans.

Any input would be appreciated. trshman

[OCMDGTO]

I have a small overflow tank mounted next to the radiator fill cap. It works fine and I put it on to be track legal. I have the same radiator, works great. It should stop spitting when it gets to the proper level, mine did.

[ZeGermanHam]

Originally Posted by OCMDGTO

It should stop spitting when it gets to the proper level, mine did.

This. If you keep topping off the radiator and it keeps puking coolant out when it's not overheating, you are overfilling the radiator. Just let it do its thing and it will stop leaving coolant behind when it reaches the proper level under normal conditions.

That said, the previous owner of my car used the windshield washer fluid reservoir as a radiator catch can. I recently went back to the stock setup. Setting up a catch can of some sort won't allow you to stop carrying coolant/water around (if that's your thing) anyway, since it isn't a sealed system like a modern car that uses an expansion tank which cycles "excess" coolant back into the system. The only advantage of a coolant catch can in an old car is that it doesn't leave coolant on the ground, but it doesn't prevent your radiator fluid level from dropping.

[Chris65LeMans]

There's a difference between a catch can that just receives excess coolant, and a (I think it's called) a coolant recovery can that has the tube from the radiator entering in the bottom so that coolant can move back and forth as needed. I have the second kind - I removed my never-used windshield washer tub, and replaced it with this one.

[Chief of the 60's]

Washer bottles have been used as overflow bottles for decades. They sorta work but do not have good enough flow. I have a small black plastic one, like in the photo, that kind of hides next to my radiator. However, you can "catch" all you want but you will still be adding fluid if you do not run a closed system. To run a closed system you will need a closed system radiator cap.

[trshman]

Thank you one and all. One response that hit home was that I'm probably over filling the radiator and not giving it a chance to find it's own operating level.
I've always had a tendency towards "more is better" which is another way of saying I have a tendency to overdo things . I'm going to back off a little
and see what the car tells me Thanks again everybody. trshman

[pfilean]

I thought back in the old days it was common for the factory owners/service manuals to ask for coolant about 1 inch below top of radiator. Primarily before cross flow radiators. This allowed for the expected expansion when hot. And this philosophy even applied for pressure caps. Then along came closed systems with recovery tanks. This change may coincide with the change to cross flow radiators when you wanted all tubes to be full for best cooling and this required the radiator to be full. And you could add coolant into the recovery tank and it would get sucked into the radiator as necessary during cooling and keep the radiator full.

[NeighborsComplaint]

Mine came out of a Camry. Fit right into a stamped recess on the radiator core.

[funkybird]

Originally Posted by pfilean

I thought back in the old days it was common for the factory owners/service manuals to ask for coolant about 1 inch below top of radiator.

I would like to clarify this point after I found this thread in a search.
I’m leaking a small amount of coolant, small trail present after engine shutdown, no catch tank.
Takes about 1 pint to ‘fill’ it up, only to puke it out again...

However this ‘natural level’ that’s 1” below the rad top is just below the top of the row of the cooling tubes, so the top row is not sitting in coolant when cold.

Is that OK? I’m thinking that’s likely to cause corrosion?

Appreciate your opinion. Thanks