I inherited my dad's '32 Ford this spring. I did a coolant flush but got to thinking that I did not put any coolant in the reservoir jar. I read somewhere that since it's not a closed system (tube just below radiator cap that runs to jar), I can just leave it empty, but have to periodically check that the coolant in the radiator is full as it will not draw any overflow back in. Car keeps the engine temp just fine otherwise. Thanks for any insight!
The are two types; one is just a container to collect overflow, the other is a coolant recovery system. The overflow style has one hose on the bottle. The recovery type container usually has two hoses - one that feeds and returns coolant depending on coolant temperature and another hose which provides overflow and venting. The overflow version need not be filled. It just collects overflow. The recovery type should have a minimum coolant level when cold to keep the overflow hose/system filled with coolant. The themo-siphon effect will purge air from the cooling system for a more efficient system.
Jar isn't pressurized. I think it can fill up, but if it fills all the way to the top, it will run down a separate section and discharge on the road/garage. You can see the overflow hose from the radiator on the bottom, then another short hose next to it where it will flow out to the ground in the picture. That probably answers my question..
Interesting, that's a recovery type tank, but being used as a catch can. What's the radiator cap and radiator neck like? Chris
That one that although it is a recovery tank, is working like the puke cans we had (and still have to) run at the drag strip. Given that you leave the proper space in the top tank of the radiator for expansion as it is and "expansion tank" you really shouldn't see much coolant in that tank unless the coolant gets hot enough and expands enough that it pukes a bit. With a cross flow we fill it to the top and rely on the tank on the side to work as the expansion tank that lets coolant return to the radiator when it cools off if it has the correct cap on it.
@mhirscher That Over flow puke tank Two hoses on bottom One as it inters the bottom of tank End's ( gravity fed in a away) That hose port goes to neck of Radiator cap port, The other inlet on the inside , internal tube Runs up High inside tank , coolant will Only Come Out if coolant gets that high level. With cap off should beable to see the Long tube , thats over flow . Puke side ! Fill radiator all the way up , let run . When Expansion happens if forces the coolant into the overflow /puke tank, As it cools , it will draw the coolant Back to into Radiator. Me after while engine running & expansion has happened ( @ running temp) I look into the expansion tank and see about where the level is if it's real close to the bottom I will add another 3 inches of coolant , so when the engine cools they're still 1 or 2 inches of coolant and the expansion tank
take the cap off and look at it on the bottom side... if it is recovery it will have a disc that pulls down..
From your pictures, it appears that it is being used as a coolant recovery system. As the coolant warms it expands and some is pushed into the recovery tank. When it cools and contracts, the coolant that was pushed into the tank is drawn back into the radiator. I'll bet your radiator cap looks like the one Alldone posted. The bottom valve is what allows the coolant to be drawn back into the radiator. If all cooling system hoses are tight, there should always be some coolant in the tank.
My suspicion confirmed, almost, and the operation fully explained by others, almost! Alldones pic shows a typical modern rad cap. You can see there's an upper seal ( right of pic) and a lower seal ( left of pic) as well as the small, spring loaded flap. Between the upper and lower seals is a chamber formed in the neck of the rad where the 'overflow' tube attaches. The remainder of the operation has been explained previously. One last point. It's worth measuring the dimensions of both the cap and the neck of the rad to be certain that the aforementioned seals mate with the rad - there's a top lip on the rad and a lower flange. Whilst caps typically look the same there are at least two sizes / depths which if inadvertently mismatched with the rad up will prevent the system from working and provide headscratching cooling results! Chris
I kinda went through a similar “learning” experience recently when selecting a radiator cap for my Ford flathead V8 powered speedster build. I have a modern rear mounted radiator from a Dodge Dakota. Learned that flatheads and most engines of that era did not typically run a thermostat, and if they did, it was a cap rated at 4 psi max. Lowest pressure cap I could find for the Dakota rad was 9 psi. While researching caps, I learned something new about how a rad cap works in terms of of the coolant recovery system. So, it really is the rad cap that will determine what kind of “recovery”system you have, and yes, most definitely ensure the cap’s mating seals are indeed correct for the radiator neck shape/size such that the cap functions properly. I’m a visual type person, so pics are worth a thousand words. This vid helps explain the operation.
Grab that titie in the middle and you'll find it will pull away and spring back when you release it, honestly!! Chris
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