NextGen antifreeze expansion tank?

[Duetto]

hi all,

has anyone designed/installed an expansion tank? nextgen told me a) heat exchanger cap will not allow backflow b) even if i found a "proper" cap, the system won't support backflow. i'm not sure why.

my goal is to make it so i can see the level and add easily when necessary.

thanks in advance.

 

[Northern Spy]

Because it is a pressure relief cap that would normally go to an overflow tank.

I posted this before in our previous long discussion about expansion tanks.

"Not to be too pedantic, but terminology is important.

Expansion tanks are pressurized. They will have a pressure rated vented cap on them. It is also possible to have a remote expansion tank when the engine has a water heater or "bus" heater attached that is above the elevation of the engine. The original expansion tank would then have a non-vented cap. Expansion tanks and remote expansion tanks are part of the pressurized cooling system, and thereby increase the cooling systems' overall volume.

Recovery tanks (or overflow tanks) are not pressurized. They rely on the vented pressure cap on the expansion tank or the remote expansion tank to function. Recovery tanks do not increase the overall volume of the system, but merely prevent coolant from going into the bilge, and allow it to be recovered back into the system when the system cools back down."

 

[Duetto]

ok, i'm talking about a recovery tank.

 

[diver dave]

This doesnt answer that question, but my NG5.5 has not consumed any AF in the first 550 hours.

 

[Northern Spy]

Because you already have an expansion tank, with an air gap to expand into. The existing cap is only for overpressure relief.

If you were to put on a two way rad cap and an overflow tank, you would have to fill the expansion tank in order for it to work.

You would have to then figure out the new pressure for the system to crack open and fully open and the volumetric expansion.

Essentially engineering a new system.

NextGen is keeping it simple. Probably to keep coolant out of the generator enclosure. A recovery tank has the potential to leak coolant where it shouldn't be.

Overfilling or head gasket leaks are likely the only way to overpressure the system currently, so low risk of failure.

 

[Bmarler]

I’ve put coolant recovery tanks on small diesels before with good result. I like the tanks with the fitting coming in the bottom as they seem to work better for me. Get one with good capacity, set it with approximately 2/3 volume above the pressure cap on the expansion tank. Get the same pressure cap as before but with a return valve on It. Put some coolant in the mostly fill the expansion tank, put an inch or so in the recovery tank and test it.
Put a mark or tape line where you started, when it got good and hot, and then when it cooled again.
This is all cheap stuff to buy, so if it all goes pear shaped you’re not out much dough.

 

[Nick F]

Recovery tanks do not increase the overall volume of the system, but merely prevent coolant from going into the bilge, and allow it to be recovered back into the system when the system cools back down."

I think this statement could be a little misleading, since it implies to me that fluid only goes into the "recovery"tank in an abnormal situation.

On my engines (and I believe this is typical) the fluid flows to the "recovery" tank every time the engine heats up, and then returns to the engine on cooldown. After messing with the coolant system on the engine the level in the recovery tank settles down after a couple of engine operating cycles and after that the recovery tank "hot" and "cold" levels are the same each time.

This assumes that the engine is functioning properly without leaks into or out of the cooling system.

To answer the OPs question, however: all you need is an engine coolant cap of the return valve style and a $20 coolant reservoir (recovery tank). Mount the coolant reservoir at about the same height, or a bit lower, than the engine coolant cap. If you mount it higher the coolant will drain out of the reservoir if you open the engine coolant cap. If you mount it lower the engine will have no problem sucking the fluid back up when the engine cools down.

 

[Northern Spy]

Not implied.

The original discussion was about increasing the volume of the coolant system, which recovery tanks do not.

People were using recovery, catch and expansion interchangeably. Which made for an inane discussion, as the nothing was defined.

For it to work, he also needs to fill his existing expansion tank. Which is probably why the tech told him it wouldn't work.

 

[Bmarler]

Not implied.

The original discussion was about increasing the volume of the coolant system, which recovery tanks do not.

People were using recovery, catch and expansion interchangeably. Which made for an inane discussion, as the nothing was defined.

For it to work, he also needs to fill his existing expansion tank. Which is probably why the tech told him it wouldn't work.

I just re-read post #1 and the goal was to make a way to easily see the coolant level. I think we’ve about covered it now.
This does seem like an area you might have some expertise in. Good to know for future.