SS Coolant Tank question

[mowpow]

For the connection at the top of the SS coolant bottle that faces the rear of the car, where should that hose connect to on the other end? I know the smaller connection pointing towards the front of the car needs to go to the T fitting on the hot water valve (with a splice for my Hervey bleeder before the hot water valve), but not sure where this other connection goes. In engine pictures I typically see people with a clear hose but I can't tell where it goes. I think it's for overflow based on searching the forums but if someone can enlighten me that would be awesome!

Thanks,
Mowpow

[DMCMW Dave]

For the connection at the top of the SS coolant bottle that faces the rear of the car, where should that hose connect to on the other end? I know the smaller connection pointing towards the front of the car needs to go to the T fitting on the hot water valve (with a splice for my Hervey bleeder before the hot water valve), but not sure where this other connection goes. In engine pictures I typically see people with a clear hose but I can't tell where it goes. I think it's for overflow based on searching the forums but if someone can enlighten me that would be awesome!

Thanks,
Mowpow

It's the overflow and is typically pointed at the ground.

[mowpow]

Ah OK, I wasn't sure if I was missing a part or something. Thanks for the confirmation Dave!

[Shep]

As in it's not connected to anything on the other end. It's there to ensure that if the coolant fills the tank, it'll have somewhere to go rather than building pressure in the system, while doubling as a channel for air to escape and enter. Just make sure the coolant exiting that hose will go to the ground and that the hose is away from moving parts and you'll be fine.

EDIT: Bah, was a wee bit late on that one.

[David T]

You can also hook it up to a coolant recovery bottle, aka, overflow tank. It should be at the same level (or as close as you can do it) to the header tank. If you do use a recovery tank you fill the header bottle to the top when cold and the recovery tank to the cold fill line. Use 50/50 anti-freeze and water. I have mine over on the left side and the hose runs across the back of the motor.
David Teitelbaum

[Bill Robertson's Sock Puppet]

You can also hook it up to a coolant recovery bottle, aka, overflow tank. It should be at the same level (or as close as you can do it) to the header tank. If you do use a recovery tank you fill the header bottle to the top when cold and the recovery tank to the cold fill line. Use 50/50 anti-freeze and water.

If you do this but leave the original style radiator cap in place absolutely nothing will happen as the system cools down -- coolant recovery radiator caps have an extra valve in them and a gasket around the neck.

[Jonathan]

As in it's not connected to anything on the other end. It's there to ensure that if the coolant fills the tank, it'll have somewhere to go rather than building pressure in the system, while doubling as a channel for air to escape and enter. Just make sure the coolant exiting that hose will go to the ground and that the hose is away from moving parts and you'll be fine.

EDIT: Bah, was a wee bit late on that one.

Just one thought on this, the system does build pressure and the cap is your pressure release valve. If you consider the reservoir tank as an expansion tank, then your set volume of coolant rises or falls based on temperature. As boiling point of a fluid rises with temperature, your coolant won't boil at the lower temperature it might have if it were at an atmospheric pressure. The small volume of air at the top of the tank above the fluid and below the cap will start to compress as the fluid gets hotter from cooling the engine. If that pressure rises above 15 psi, the release valve pops and vents the pressure. It would initially be air, however will be followed by coolant in the form of steam. The reason for this is because the coolant got hot enough to be above the boiling point at atmospheric pressure, but so long as it remains pressurized, it would stay a liquid. If you immediately remove the pressure, it flashes to steam to remove the heat and change phases. Same thing happens inside a boiler such that if you open up a blowdown line, it will flash to steam as it leaves versus pour out as a liquid.

Interesting you mentioned the cap will also allow air back in. I'm not sure what exactly is going on inside the release valve mechanism of the cap, but not all relief valves will do this. And you can see how this could be a problem. If you flash off a bunch of your coolant through the release valve in the cap, so now you have less fluid in the system, when it starts to cool it will begin to pull a vacuum. If there is no way for air to get back in, the vacuum could be strong enough to damage a hose or the tank. You see this sort of thing at times at industrial sites where say they are pulling a liquid out of a tank, but neglected to valve in or design in a vacuum breaker of some kind or otherwise a way for air to get back into the tank. The forces there are often sufficiently strong enough to cave in the whole tank.

I believe when the old standards were being developed for engineering, they chose one atmosphere (or 14.7 psi) as the maximum pressure allowed before you had to have your vessel certified as a pressure vessel. I believe this was the main driving factor for why car coolant systems are not rated for higher than that 15 psi, so they would not have to be certified as a pressure vessel.

[mowpow]

Back on this. I keep finding coolant under the rear after driving. I figured I had a joint coupler leaking but I saw coolant coming out the over fill hose. When cold there is barely any coolant in the reservoir tank so that seems wrong. Is this an issue with the cap?

[Doogie]

Back on this. I keep finding coolant under the rear after driving. I figured I had a joint coupler leaking but I saw coolant coming out the over fill hose. When cold there is barely any coolant in the reservoir tank so that seems wrong. Is this an issue with the cap?

MowPow, I have that same scenario! My cart doesn't overheat or anything like that, but a lotof time after a run I see coolant coming out of the overflow tube. Bad Cap?

[DMCMW Dave]

Replace the cap. If it still happens, replace the head gaskets. But it's probably the cap.

Sometimes the cap is OK and the surface on the bottle is bad, especially on some of the older aluminum tanks.

[rddmc]

You can also hook it up to a coolant recovery bottle, aka, overflow tank. It should be at the same level (or as close as you can do it) to the header tank. If you do use a recovery tank you fill the header bottle to the top when cold and the recovery tank to the cold fill line. Use 50/50 anti-freeze and water. I have mine over on the left side and the hose runs across the back of the motor.
David Teitelbaum

How large is your overflow tank? Would it be possible for you to post a picture showing where/how you installed it?

Thanks,

Rod
10921

[David T]

If you keep blowing coolant maybe you are overfilling the header tank. It should be just a little less than 1/2 full when cold. My overflow bottle is about 3 quarts but I never measured it. As Dave S says, replace the rad cap. If you see bubbles in the coolant you probably popped a head gasket.
David Teitelbaum

[mowpow]

Cool I will try to replace the cap first. It no longer spews when there is about 1/4 worth of fluid in the SS tank. I also have a sight glass to see the fluid level and I noticed it looks like there are reddish brown crystals in it, almost like it burned or something. Rust particulates maybe, I dunno. Will report back.

[Ron]

Once you are sure all air is out of the system, top it off and put a few miles on it with the engine warm. It will pus out the extra. Once it cools take a look at the level -- That is about where you should fill it too in the future.

Make sure you get the right cap (especially sealed v/s recovery type). I forget the number, but you can ask for a AC RC15 crossover for stock style (fwiw, you don't want to pay for the original AC since they fit old Vetts and other muscle cars and are getting rare).