Coolant Expansion Reservoir

[AlanO]

As part of my electrical refit for our 38-200, I am considering moving the coolant reservoir because it is currently located in the starboard cockpit locker at a place where I would like to mount an easily accessible battery switch. However, I have other motivations. As can be seen in the photo, the current reservoir is empty. One of the POs mounted the reservoir at an elevation higher than the engine (Universal 5432) reservoir, so it is useful for capturing expanding coolant, but useless for gauging the coolant level when cool. While I really have no experience in such items, it also seems to be relatively small because a larger volume would allow for more expansion without overflowing, right? I'm thinking of keeping it in the same general location, but moving it to the right (forward) and lowering it so coolant is visible near the low mark when the engine is cool. While I'm at it, I'm thinking of getting something larger with a decent fitting cap. I suspect something suitable could be found at any auto parts shop. Are there any ABYC standards I should be aware of?

Where have people typically mounted expansion reservoirs and what size?

Thanks.

Alan

 

[Christian Williams]

My reservoir is also (much) higher than the coolant tank. It never shows any coolant, although I keep the coolant manifold full.

I think of it as an overflow tank. It's connected to the base of the pressure cap ("radiator cap"). If the engine overheats and the coolant boils and expands, the overflow tank is there to receive it. Theoretically, when it cools down the coolant just siphons back to the manifold tank.

I wouldn't hesitate to move it to any logical location, but others may know more.

 

[JSM]

I agree with what Christian said above. As long as the manifold is full you are in good shape.
Having some coolant in the jug can serve as a good way to visually check that the manifold reservoir is full. I realized this one day when I removed the radiator cap to check the fluid level and watched anti freeze gush out as the overflow tank emptied into the manifold.
I've also seen setups on boats where the overflow hose just empties into the bilge.

 

[Loren Beach]

I moved our (new/replacement) expansion container back inside the engine compartment, from its factory location over in a nearby lazaretto. The coolant level inside is an inch or two higher than the top of the take-off point at the pressure cap. That was advised by our engine installer. He said that the tank should not be lower than the top of the engine,
There is a picture of it in this blog entry. https://ericsonyachts.org/ie/ubs/new-hour-meter-halon-status-light-part-1.671/

 

[Pete the Cat]

You probably would not want it lower than the neck of the manifold tank, but you can mount it where ever it works for you. You would have be running the engine really hard and with some compromised cooling issue to get much use from it if your engine runs at 160 degrees. Not much steam produced to escape and condense.

 

[AlanO]

Thank you all for your responses. I think I will keep it at its current elevation, but move it forward to allow for the battery switch.

Alan