Overflowing coolant????

[lotsagas4u]

Have a newly rebuilt 36LB engine, with a new Brassworks radiator in my 33 coupe. Radiator has 7 lb cap with dummy grill neck. Problem is after running 50 mph, and stopping, coolant comes out of overflow tube. Coolant was filled to top of radiator neck. The water pumps are Drake. Engine temp is around 180, with NO thermostats. Are the pumps pushing coolant faster than the tubes can drain? I topped the radiator off this morning, it had lost around a half gallon. This was after a few short trips. Thoughts? Thermostats to slow down flow? Expansion? THANKS

[petehoovie]

Usually, these Flathead cooling systems will find their own optimum level. Let it puked out as much water as it wants and keep an eye on it. I think that you're overfilling the cooling system in your car....

Oops! - I failed to consider that you have a 7 lb. cap. I was thinking about a non-pressurized system like I have in my '34. Disregard my comment above....

[RalphM]

If it's not overheating, I wouldn't worry about it. Just don't add coolant every time you stop and it will find its own level as mentioned. I would however think about putting thermostats in. JMHO
Exact same thing happened with my car .

[RKS.PA]

You might think about a recovery tank unless you don't like the looks of one under the hood. The 59AB in my '39 would "puke" the excess in the system and sometimes it was embarrassing if I was parked in a neighbors drive!!!

[Capt Kirk]

My car would puke coolant out the overflow (non pressurized system) all the time till it found it's "sweet spot". Last year I had a pump leak and sent both to Skip for rebuild. At that time I also installed "snail spring" thermostats at the head. I no longer have the embarrassing flathead runny-nose. I believe Skips pumps pump more coolant than the stock ones so my only explanation is that the t-stats brought things into control. I did a stop-and-go cruise last summer at 90* temps and all went great.

[FlatheadTed]

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X2 What's been said ,add a catch can and monitor how much it dumps .Start with it two to three pints down ,If its expels more than that I would suspect a compression leak .After cooling it should be full with draw back in from the catch can ,Skips pumps will pump more but it should not be able to over come 71b .Ted

[G.M.]

You should not get ANY coolant going out the over flow with even a 4 lb
pressure cap if the temperature runs below 205. If you get coolant out the
over flow you have a problem. First make sure the pressure cap is working,
to work the extended rubber bottom of the cap has to hit and seat on the
brass washer down in the bottom of the filler neck before the underside of
the top of the cap hits the top of the filler neck. For some reason there are
a lot of caps that don't seat at the bottom. You don't need more than a 4 lb
cap. Also fill the radiator up to about 1/2" from the top of the filler neck,
don't listen to this baloney that coolant will seek it's own level. You need the
full 22 quarts for good cooling. With the pressure cap use a small recovery
bottle sitting on top of the left frame rail. Run a hose from the over flow tube
to the bottom fitting on the bottle and a short hose up near the top to vent
any pressure. The pressure in the system and expansion of the coolant will
cause a small amount of coolant to be forced into the bottle. As the engine
cools at 155 degrees there is a vacuum in the engine, this vacuum sucks the
coolant from the bottle back into the engine and now next time you start you
have a full supply of coolant. This stays this way for at least a year. If the
temp don't get over 205 and coolant is coming out the over flow from the
top of the bottle you have a compression leak putting pressure in the coolant
system. I have had to put a rubber washer on the brass seat on a lot of
radiators. G.M.

[lotsagas4u]

New radiator holds nearly 5 gallons, that is up in neck, I cant see into this radiator. May order a set of Shewmans 180 thermostats also. Will check the cap, thanks for the reply's.

[G.M.]

Originally Posted by lotsagas4u

New radiator holds nearly 5 gallons, that is up in neck, I cant see into this radiator. May order a set of Shewmans 180 thermostats also. Will check the cap, thanks for the reply's.

Get a flashlight and mirror, you need to see the coolant level. You need
to get coolant loss problem fixed before adding stats. Stats have nothing
to do with cooling, they only help to raise the operating temps. G.M.

[rotorwrench]

I agree. The system should hold pressure with a 7# cap. If it has that amount of pressure build and the cap is sealing properly then compression is leaking into the coolant system most likely at a head gasket. There could also be a crack somewhere in the head or deck.

A new radiator should pass coolant faster than the pumps can push unless there is a blockage somewhere.

[JimG]

I put a Stainless Steel coolant overflow tank from Speedway on my radiator late last year. It has a 7 lb cap with a 59 AB engine in a 1934 Fordor. It used to puke out coolant even if I left it at whatever lower level it seemed to want. Now I can fill the radiator up and it doesn't puke out to the ground. The engine also seems to run cooler now that there is more coolant in the system. I was able to add about another gallon from the level it wanted before. Haven't used it in hot weather yet, but this seems to be a good addition.

[Flathead Fever]

If you look at the overflow tank on a modern car it has a cold level and a hot level. The difference between those two lines is the volume the coolant will expand when it reaches operating temperature.

If you were to fill a 2017 vehicle's overflow tank to the top while the engine was cold it would puke out coolant too just like your flathead, If you don't want your flathead or any engine without an overflow tank from puking on the ground you need to leave room for the coolant to expand in the top tank.

I see engines at car shows puke out coolant all the time after they are shutoff. This is because the cooling system continues to absorb heat from the block and heads when the engine is turned off but now there is no functioning cooling system to remove that absorbed heat so the coolant gets hotter and it expands even more and it pukes.

After its all done puking let it cool down and then check the coolant level. This is the "sweet spot". This is the level you are going to fill it up to in the future and no further. Before, you were looking into the upper tank thinking it was not completely full when it was cold. If you released the pressure and removed the radiator cap at 180 degrees (don't do it) you would find the coolant right at the top. It does not need to be full when its cold. You do loose a little coolant in a system without an overflow tank and you will need to bring it back to the sweet spot every once in while

With an overflow tank the radiator is always filled to the top. When the coolant expands its pushed out into the overflow tank. As the coolant cools down its volume shrinks creating a vacuum that sucks the extra coolant from the overflow tank back into the radiator. The system is sealed so it rarely needs any coolant added. Its also a good idea because with a full radiator all the time there will be less oxygen in the system to cause corrosion in your cooling system. This back and forth flow between the radiator and overflow bottle is done through a little valve in the radiator cap. If you ever see a radiator hose collapse after the engine has cooled off that little valve in the radiator cap that allows the coolant to flow back into the top tank is not opening.

What about pressure? Old cars never had pressure caps because they did not exist yet so why do we have them now. Antifreeze was extremely expensive when it first came out and most people ran straight water. The problem with straight water is it turns to steam pretty easy. A lot of older engine blocks were cracked from the pressure of steam. Steam works really well in an old train, not so much in a flathead. When water turns from a liquid to steam it expands its volume by 1700 times. Its going to blow the hoses apart, the solder joints in the radiator and probably crack everything in the engine it touches. We cannot let it turn to steam. The reason we install pressure caps on radiators is for every 1 lb. of pressure we put on the cooling system we raise the boiling point (the point where it turns to steam) by 4 degrees. If we can raise the point the coolant turns to steam by 48 degrees its very unlikely you will ever let your engine get to 260 degrees. Modern radiators can withstand 12 lbs. of pressure but not the original flathead radiators. I was told by an old-time radiator guy it was not because the radiator tanks were thinner but because the solder joints were not wide enough to hold more than 4 lbs. of pressure.

You might have also read stories where "back in the day" people would cutoff every other impellor fin on their flathead water pumps to reduce the coolant flow to get them to run cooler or they installed 5/8 inch restrictors in the upper hoses to slow down the flow so it would cool better. Do you think if that was really a cooling improvement Ford would not have figured out what rate of flow produced the best cooling results. I believe these people have confused the flatheads that raced on the dirt tracks with the ones meant to bring home the groceries. It's just a guess but I'm thinking at 5000 rpms those two water pumps pushed so much coolant that it could not flow fast enough through the radiator so it backed up and went out the over flow tube. So they had to come up with a way to cut down the flow while running ten laps at 5000 rpms. Normally you want as much coolant flowing through those radiator core tubes as you can get so more heat can be sucked out faster by the cooling fins.
.

[rotorwrench]

Comparing a modern system to an old flathead system is not very good science. Many modern radiators have no room for expansion or even a filler port so they have to have an overflow/expansion system. Engine coolant expands around 4%. Engineers understood this pretty well before the turn of the previous century. Coolant levels are generally set some amount above the tubes in the bottom of the upper tank. The tank doesn't have to be full for the system to function. Rule of thumb back then was if your thumb touched the coolant when inserted in the neck then there was a sufficient amount of coolant in the tank to operate the engine. If it drops to a point that you can see the tubes when the engine is cold, then there is a problem with excessive pressure build. It shouldn't lose that much coolant in a radiator tank that large.

One problem I can see already is that the new Brass Works radiator has a hidden neck that may or may not allow a person to see the actual level in the tank. At least with an original radiator with the add on 4 # relief valve in the overflow line, you can still see the bottom of the upper tank when the coolant level is too low.

You can install an overflow tank and it may cure the problem but if it keeps building pressure then the problem is elsewhere. We had a lot of flathead cars & trucks when I was a kid and we never needed an overflow tank for any of them. We did have to get the radiators rodded out on occasion when they needed it though.

Another point is about water pumps. They are not a pressure type pump. If pressure backs up, they just can't push the fluid since they are basically just a centrifugal type pump. They work very well to keep low viscosity fluids moving through a recirculating flow type system. A positive displacement pump would never have been well suited for this type application.

The cylinder heads might need to be retorqued.

[The Brassworks]

well said flathead fever