Radiator overflow bottle suggestions

[Buick35]

On my 35 Buick on a non pressurized cooling system I was wondering if I should install an overflow bottle of some type.I don't think it came with one.I've seen cars that used old whisky bottles. Not sure what to use if any,pictures appreciated.Thanks,Greg.

[Graham Man]

Found this one... I would use a simple can and paint it black, the hot rod guys have tons of them just Google "overflow bottle".  You could put a hose on it and locate the bottle out of view.  This one might get you in trouble with a humorless State Patrol. 

 

If your radiator is overflowing you have a different problem, typically no bottle is needed.

 

[Buick35]

Thanks,my son had one on his 66 Mustang and use a fireball whisky bottle. I later found out that anti freeze is an ingredient in that whisky, not sure if that's true or not.

[trini]

This is a little puzzling to  me. A pressurerize system is designed for the later high compression engines that generate more heat than the  older engines . The pressurized cap has a relief valve to allow extra fluid to escape into the bottle when the engine is hot and allows the liquid to be sucked back into the radiator when the engine cools. The overflow tank must maintain a certain  level of fluid at all times. The older rad caps have no such relief valve to allow the liquid to escape when the engine is hot and allow the liquid to be sucked back from the overflow tank. The older radiators have the overflow tank built in.  So what is the use of adding an overflow  tank or bottle  in the first place ?

May be you should have the radiator cleaned and checked if the engine is overheating.  

[nickelroadster]

You won't loose the coolant.  Nothing is really wrong with the system, the coolant is just expanding when it get hot.

[Buick35]

My radiator has an overflow tube on it that normally just goes to the bottom of the car.I just thought I'd add a bottle to catch any coolant just in case.

[PFitz]

How well it will work depends on the design of your radiator cap.

 

If it's just an overflow tube where the cap only seals below where the tube attaches to the filler neck, it will expel hot expanded fluid, but it won't draw back because the cap is not sealed to the  top of the radiator fill neck above where the tube comes out the side of the neck.

 

So, with a cap like that the only thing gained by having an overflow bottle is catching the overflow. But what do you intend to do with it then ? 

 

The get the fluid to go back into the radiator when it cools, you'd need a cap with a double seal, one seals at the bottom of the neck and one on top. The bottom seal is spring loaded to work at a specific cooling system  pressure. The top seal provides a much stronger seal so that the fluid that gets past the bottom seal must go back and forth to the overflow bottle. 

 

Paul

[Grimy]

39 minutes ago, PFitz said:

How well it will work depends on the design of your radiator cap.

 

If it's just an overflow tube where the cap only seals below where the tube attaches to the filler neck, it will expel hot expanded fluid, but it won't draw back because the cap is not sealed to the  top of the radiator fill neck above where the tube comes out the side of the neck.

 

So, with a cap like that the only thing gained by having an overflow bottle is catching the overflow. But what do you intend to do with it then ? 

 

The get the fluid to go back into the radiator when it cools, you'd need a cap with a double seal, one seals at the bottom of the neck and one on top. The bottom seal is spring loaded to work at a specific cooling system  pressure. The top seal provides a much stronger seal so that the fluid that gets past the bottom seal must go back and forth to the overflow bottle.

Yes!  A friend modified the necks on his 1927 and 1928 Buicks to achieve that, then used the remote expansion tanks from early 1960s FoMoCo V8s with  4-lb pressure caps.  I wish I had photographed the details.

 

The bad news for @Buick35 is that, if your radiator neck arrangement is like that on my 1934 Buick 56S of happy memory (and on my 1934 Pierce currently), the filler is underhood and at the very end of a curved piece leading to the top tank--making such a modification virtually impossible.  What I've learned to do is to top off the radiator only when the coolant is fully hot and expanded.  If you fill to the top cold or cool, you will overfill as there is no room for expansion that coming with operating temperature.  In earlier system with the cap directly atop the radiator, you can see the core and fill to just above the core itself, leaving room for expansion.

 

At highway speeds, it is sometimes possible for the overflow caused by expansion to actually create a suction and pull additional fluid out of the radiator.  Be sure that your water pump is not pulling air in at speed, and that your lower radiator if more than 5 or so inches long is not collapsing under the tremendous suction provided by these pumps.  In SOME cars (my 1934 Pierce), a 50% mix of EG coolant would foam and displace coolant out the overflow at speed.  With my climate, I run no anti-freeze but a generous amount of anti-corrosion / anti-cavitation additive.  When I have had to add anti-freeze for tours where the temps might drop below freezing, I add only the smallest dose of anti-freeze for the temps anticipated.  My choice for coolant additive is Pencool 2000 for cars with no anti-freeze at all, Pencool 3000 for systems with any amount of anti-freeze.

 

In my 1934 (and my 1930 Pierce), both with no overflow recovery contraptions, I only have to add perhaps 6-8 oz of coolant (see below) every 600-700 miles.  I carry a one-gallon jug of water pre-treated with 5 oz of Penncool (dose is 1 oz per quart of cooling system capacity, the extra ounce is for makeup).

[trini]

PFitz, you are right on the ball. You see the engines that uses the overflow tank has an outlet pipe on the filler neck to attach the flex tube to the overflow tank. These engines are designed to run at higher temperatures, sometimes at 180 degrees, therefor the 180 thermostat. Mostly high compression engines like 9 to 1 .

As an example my 225 Dodge engine , compression probably 5 to 1, the overflow tank is built in the rad. When I fill the rad and run the engine hot with the cap off the water boils over and flows outside the rad through the filler. When I run the engine with the cap on, the engine gets hot, the extra liquid flows through the overflow tube. At that point the cooling/heating system is leveling itself by throwing the extra fluid out through the overflow tube . So if you like you may catch the overflow. That has to be done with the car stationery. Then the cooling system is just fine.

I am subject to correction here . I believe these engines suppose to run at 150 degrees . That what the thermostats are rated at. So check your MOTOR METER when the engine is hot. It should read 150 degrees

Cheers.

Harry in Thornhill.