Coolant Expansion tank

BruceB · Veteran Member

Coolant Expansion tank

Stanley · Guru

We have two completely different tanks.

1) One is a Pressure tank which one would use when the hot water heater is above the engine. The plumbing arrangement is shown here https://www.betamarinenc.com/wp-content/uploads/2016/05/HEADER-TANK-PIPING-SYSTEM-DRAWING-2.pdf

2) the other is a coolant recovery tank which connects to the clear tube under the pressure cap on the manifold. As the coolant gets hot, it expands a bit. Normally the excess just goes past the pressure cap and into the bilge or the pan under the engine. The expansion tank (recovery tank) will hold this excess and when the engine cools down, the coolant will be sucked back into the cooling system to stop you having to fill the system every time you use the engine.

Photos of both are shown

BruceB · Veteran Member

Stanley,

Thank you! Would you then attach the coolant recovery tank to the pressure header tank instead of the engine manifold?

Stanley · Guru

If you are following the diagram on this page www.betamarinenc.com/wp-content/uploads/2016/05/HEADER-TANK-PIPING-SYSTEM-DRAWING-2.pdf
It is adviseable to block off the overflow under the cap on the manifold and then the only blow off connection will be at the pressure tank where you connect the recovery tank.

BruceB · Veteran Member

Stanley,

That makes sense. What's the best method to block the manifold over flow tube? Also, what's the reasoning for attaching the expansion tank to the lower manifold port instead of the higher block port? I would think for the sake of removing air in the system that it should be attached to the higher block port.

Thanks!

Stanley · Guru

BruceB wrote:

That makes sense. What's the best method to block the manifold over flow tube? Also, what's the reasoning for attaching the expansion tank to the lower manifold port instead of the higher block port? I would think for the sake of removing air in the system that it should be attached to the higher block port.

You can block off the lower vent connection with a short piece of tubing with a bolt in it and 2 small clamps.

I do not know why you would want to connect the overflow to the lower port. This is not shown anywhere is our literature

BruceB · Veteran Member

I think you misunderstood my point on the second part of my last comment. I wasn't talking about the expansion tank vent vs. the engine manifold vent. I was talking about the water heater hose. Your diagram shows the water heater hose attaching to the manifold port, which is lower than the port on the head. I was just wondering why. Wouldn't that create an opportunity for air to get trapped in the manifold, as opposed to attaching the expansion tank to the port on the head?

Thanks!

Stanley · Guru

No. If you follow the drawing correctly, it works.

Blue Moon · Veteran Member

Regarding: 2) the other is a coolant recovery tank which connects to the clear tube under the pressure cap on the manifold. As the coolant gets hot, it expands a bit. Normally the excess just goes past the pressure cap and into the bilge or the pan under the engine. The expansion tank (recovery tank) will hold this excess and when the engine cools down, the coolant will be sucked back into the cooling system to stop you having to fill the system every time you use the engine.

Understood that coolant expanding past the pressure cap would go out the clear tube, but routed to the recovery tank instead of to the bilge. But when everything cools down, how does the "extra" coolant that went to the recovery tank get back past the pressure cap into the main coolant tank? Doesn't the pressure cap seal prevent "recovery"?

BruceB · Veteran Member

When the engine cools down a vacuum is generated in the engine coolant system, due to the missing coolant that was discharged while the engine was hot. There is a small one-way valve in the center of the coolant cap that allows the coolant to be sucked back into the engine from the recovery tank.

BruceB · Veteran Member

Stanley,

I blocked the engine coolant overflow vent like you suggested, but I still have coolant leaking into the pan under the engine. What appears to be happening is it is leaking through the coolant recovery one-way valve in the cap. Without pressure in the system the one-way valve doesn't really work, so the coolant is leaking through that valve and out over the top of the cap as the top of the exhaust manifold is wet with coolant.

Before I blocked the vent as you suggested it was leaking out the vent. Now that the vent is blocked, it just rises up to the top of the cap and overflows. I sucked all the coolant out of the pan and dried the pan yesterday. Today there is more coolant in the pan. At least a quart.

Suggestions? Are there non-vented caps or other solutions that will prevent the coolant from overflowing and winding up in my pan?

Stanley · Guru

This is just a faulty cap. I suspect that if you replace it, the problem will go away.
You should have no problem finding one at your local auto parts store.

BruceB · Veteran Member

This cap is a 14psi cap I purchased at Napa Auto Parts. The one that came with the engine is a 95kPa cap, and it leaked even more. My pressure tank is about 2' above the engine, so there is a bit of head on this cap. My thinking is that the vacuum valve is letting the coolant escape as there isn't enough pressure to allow the valve to stay closed.

Stanley · Guru

I think that the fault is in the filler neck, not the cap. It may have had someone stand on it during installation causing it to lose it's original shape.

BruceB · Veteran Member

That could be possible. What are my options?

Stanley · Guru

If the filler neck is faulty, you could carefully straighten it or you could replace it.

BruceB · Veteran Member

It doesn't look noticeably bent. Wouldn't that be a warranty replacement if it was leaking due to being bent?

Stanley · Guru

If it is faulty, the warranty issue depends on what caused it.
If someone bent it during installation on the boat, they should be held responsible.
What is the WOC number of your engine?

BruceB · Veteran Member

K41585

No damage during installation. I was involved and we never touched the top of the engine to anything. Again, the filler doesn't look deformed in any way.

Stanley · Guru

This engine was not brought in through us here in NC.
Have you considered talking with the dealer who supplied your engine?

BruceB · Veteran Member

Correct as I'm in Oregon. I'm a member of your forum as it is the quickest and best information I've gotten regarding Beta Marine. I hope you're ok with me being a member. I'll reach out to them and see what they say. Thanks!

Stanley · Guru

You are most welcome to be a member of this forum as is every other Beta owner. In fact, we have quite a number from other countries and the exchange of ideas is always interesting.
However, when there is a warranty issue, this is best dealt with locally.

BruceB · Veteran Member

Understood. I'll carefully examine the filler and if it is indeed deformed or flawed, I'll reach out to my dealer. Thank you. I certainly enjoy the information I get from this forum. Much appreciated.

NeilMcCubbin · Veteran Member

We have has the system Stanley describes for years, with no leakage from the cap on the engine.
I would try a new one from and auto-parts store. Make sure it is clean

BruceB · Veteran Member

Thank you for you comment. How high is the expansion tank above the engine?

I've now tried 3 caps, the one that came with the engine and 2 new ones from the auto parts store. I reached out to Beta UK and they are sending me a new filler neck. I'll report back after I receive and install it. Hopefully the leaking stops.

I put ball valves on each fitting for the water heater (at the engine) to isolate the water heater from the cooling circuit, per ABYC. With the valves turned off the leaking stops.

NeilMcCubbin · Veteran Member

I posted in 2020 that the coolant cap on the 2014 engine had not leaked

Last month, Nov 2022, it leaked. A replacement from NAPA fixed it.

BruceB · Veteran Member

I failed to follow up on my leaking coolant cap. The problem was a dented filler neck. Once I received a replacement from the UK my leaking problem went away. 900 hours on the engine and not a single leak.

Blue Moon · Veteran Member

Nice. This has been working very well for us.