What is it?

[Gjesion]

I think it is a coolant overflow tank. The large hose comes the neck of the fill tank above cap seal. The small hose goes overboard. The car (Superformance) is new to me and each time I drive there is coolant leaking from the small hose. I looked on the Mr. Gasket website and found nothing like it. It is running a 460 and was built in 2000. Any ideas of exactly what it is and how it should function would be greatly appreciated!

Regards,
Jerry

P. S. the coolant fill tank is filled to ~ 3/4" below the opening flange, and after looking underneath, it is puking out fluid as I drive.

[cycleguy55]

Originally Posted by Gjesion

I think it is a coolant overflow tank. The large hose comes the neck of the fill tank above cap seal. The small hose goes overboard. The car (Superformance) is new to me and each time I drive there is coolant leaking from the small hose. I looked on the Mr. Gasket website and found nothing like it. It is running a 460 and was built in 2000. Any ideas of exactly what it is and how it should function would be greatly appreciated!

Regards,
Jerry

P. S. the coolant fill tank is filled to ~ 3/4" below the opening flange, and after looking underneath, it is puking out fluid as I drive.

I can't confirm it, but I suspect it's a coolant recovery system. When the coolant in your engine and 'fill tank' (likely an expansion tank - post a photo) expands it expels the additional fluid through the larger hose into the coolant recovery tank. When that gets too full it dumps the excess through the smaller hose and, based upon what you wrote, onto the ground.

As the engine cools, it will draw the coolant from the coolant recovery tank back into the expansion tank. Coolant should be added to the recovery tank if necessary, not the expansion tank.

[Gjesion]

Brian,
It is even more strange. There is another large hose that exits the Mr. Gasket tank which is another vent? It goes down to the frame and is open. Attached is a pic of the coolant fill tank. My assumption is the other smaller hose goes to the radiator. I am puzzled by all of this......

By the way, how much coolant should be in the fill tank?? It is currently filled to 3/4" from the bottom of the neck.

Regards,
Jerry

[patrickt]

If that's a homemade coolant recovery system it's possible that the creator did not use a recovery type cap. A lot of people don't know that there are two types of caps. See this thread: Overflow Tank question and references to the Putnam Suck Test to distinguish between the two.

[Gjesion]

This is an actual recovery system. I tested it by injecting water into the inlet then sucking it back out. This particular model has a drain (which I tested and found working) along with an overflow. I did check the cap and it is the proper one.

After a run today there was no coolant coming from the overflow tube. The engine was running at ~93 C and I put about 10 miles on it. Looking into the surge tank the fluid level had gone down. This suggests that the coolant level was too high and it was puking it out until it reached the appropriate level. I had a similar issue with an MGA I had.

Thanks to those who responded....

Regards,
Jerry

[patrickt]

With these cars, if it's a real problem then it will return; real problems never go away on their own. So if the problem doesn't return, it was never a real problem to begin with.

[louza]

Hi, I agree the problems don't go away on their own.

Mini Militia App Lock

[bkozlow]

It appears that this cooling system the way it is setup is un-pressurized unless the Mr Gasket tank is pressurized which I doubt. I would suggest closing off the large hose on the fill tank and replacing the small hose from the cap with that hose to the Mr Gasket recovery tank. This gives you a pressurized system with over flow going to the recovery tank. Fill the recovery tank half full and your fill tank up, as the engine heats up the water will expand and come out the cap over fill to the recovery tank purging any air in the system. Upon cooling, the water because of the contraction of the liquid will suck water back into the system through the radiator cap from the recovery system, this is how these systems are designed to work since you say you have that type of cap. I could be wrong but this is where I would start.

BillK

[jhv48]

You are correct. The auxiliary tank is an overflow recovery tank. Fill the first tank about three fourths full and leave the auxiliary tank empty. Once the engine heats up, the coolant will expand into the recovery tank and then reverse its flow back to the first tank upon cooling. Any extra fluid will flow out of the auxiliary tank onto the ground until equilibrium is reached.

[sunman]

That’s the cheapest cap made by Stant/MotoRad
If the rubber seals are as old as the small recovery hose next to it…
You see where I’m going with this rite