Northern Lights Genset Coolant Everywhere?!!?

[Paradise1]

I have a Northern Lights genset (M673) on my Hunter 50cc. It only has 124 hrs on it. I went to change the oil and oil filter yesterday, and the unit was sitting in a pool of coolant, which I cleaned up. I noticed that the Coolant Recovery Tank was completely full to the brim. I finished changing the oil and started it up to run for about 15 minutes. Ran beautifully and within temp range! Opened up the compartment, and once again, coolant -- everywhere! What in the world, everything looks completely normal. Anyone have any idea what might be happening or what the problem might be?

[donradcliffe]

Next time run it with the cover off, and look for where the coolant is coming from. I assume you dropped the coolant level in the recovery tank before you ran it again. Some expansion is normal as the genset heats up.

[DougR]

The smaller hose clamps on each end of the heat exchanger separate the sea water from the coolant. If these clamps get loose, the pressure from the sea water pump can push past the clamps and over fill the coolant system, forcing coolant out of the overflow bottle. The engine won't overheat as it is still full of coolant, but the coolant will be contaminated by sea water and will need to be changed.

DougR

[Paradise1]

I did not add coolant after I discovered the coolant all over the first time, even though a significant (about a 2 pints) came out, thinking it would equalize because of ambient temperature changes. Just started it again and coolant is only coming out of the Coolant Recovery Tank overfill hose...

[Paradise1]

Originally Posted by DougR

The smaller hose clamps on each end of the heat exchanger separate the sea water from the coolant. If these clamps get loose, the pressure from the sea water pump can push past the clamps and over fill the coolant system, forcing coolant out of the overflow bottle. The engine won't overheat as it is still full of coolant, but the coolant will be contaminated by sea water and will need to be changed.

DougR

Thanks for the info. Checked clamps. All are tight.

[Kelkara]

Originally Posted by DougR

The smaller hose clamps on each end of the heat exchanger separate the sea water from the coolant. If these clamps get loose, the pressure from the sea water pump can push past the clamps and over fill the coolant system, forcing coolant out of the overflow bottle. The engine won't overheat as it is still full of coolant, but the coolant will be contaminated by sea water and will need to be changed.

DougR

Hi Doug, can you explain this a bit more, because I have a similar problem with my engine, and I can't quite visualise what you are describing here.

thanks.

[DougR]

The heat exchanger tank contains the HE element, and the element sticks out of the tank at each end. The sea water flows thru the inside of the tubes in the element, and the antifreeze surrounds the tubes on the outside of the tubes within the tank. On each end of the element are rubber end caps that clamp both to a flange on the tank and also to the body of the element. These caps locate the element within the tank. There are two large hose clamps on each end of the heat exchanger. The clamp closest to the HE tank clamps onto the tank flange, and the slightly smaller clamp squeezes onto the body of the element. So coolant resides in the tank and can flow slightly between the gap of the tank and the element, but then is stopped from moving further by the clamp further away from the tank.

Seawater flows from the pump to the end of the rubber cap and then into the HE element. The only thing that stops the mixing of coolant and sea water is the pressure of the second clamp squeezing the rubber cap against the body of the HE element, so if that clamp is loose there can be some seawater forced into the coolant.

This is a little difficult to describe, but if you look at the parts breakdown on the Northern Lights website it may become clear to you. The same system is used on the Volvo Penta 2020, 2030, etc. engines as well as other Bowman coolers so you may find a parts breakdown in several places.

Hope this is helpful.

DougR

[DougR]

Further thought.......

Rust or other restriction in the exhaust elbow will cause a pressure rise in the sea water system and may help force sea water past the clamps and into the coolant.

DougR

[Kelkara]

Thanks Doug ... That helps a lot, your description is pretty clear ... not sure if it applies to my engine or not, but when I get back to the boat I'll certainly investigate.

OK ... I'll now leave this thread alone for Paradise1 to fix his generator.

[onewadd]

Originally Posted by DougR

The heat exchanger tank contains the HE element, and the element sticks out of the tank at each end. The sea water flows thru the inside of the tubes in the element, and the antifreeze surrounds the tubes on the outside of the tubes within the tank. On each end of the element are rubber end caps that clamp both to a flange on the tank and also to the body of the element. These caps locate the element within the tank. There are two large hose clamps on each end of the heat exchanger. The clamp closest to the HE tank clamps onto the tank flange, and the slightly smaller clamp squeezes onto the body of the element. So coolant resides in the tank and can flow slightly between the gap of the tank and the element, but then is stopped from moving further by the clamp further away from the tank.

Seawater flows from the pump to the end of the rubber cap and then into the HE element. The only thing that stops the mixing of coolant and sea water is the pressure of the second clamp squeezing the rubber cap against the body of the HE element, so if that clamp is loose there can be some seawater forced into the coolant.

This is a little difficult to describe, but if you look at the parts breakdown on the Northern Lights website it may become clear to you. The same system is used on the Volvo Penta 2020, 2030, etc. engines as well as other Bowman coolers so you may find a parts breakdown in several places.

Hope this is helpful.

DougR

What DougR said. I had the same issue on my Hunter 420 (same genset) and found the rubber ends (each end of the heat exchanger) to be soft. Replaced them and flushed cooling system (three times) added new coolant and that was over four years ago.

[boatbod]

Can you measure the water jacket temperature with the engine running under load? If the unit is slightly over heating, the coolant may be boiling and pushing past the pressure cap on the heat exchanger tank. The expansion bottle can only hold so much before it overflows too.

Check the pressure cap for damage to either the inner rubber gasket.

[mcope431]

Originally Posted by Paradise1

I have a Northern Lights genset (M673) on my Hunter 50cc. It only has 124 hrs on it. I went to change the oil and oil filter yesterday, and the unit was sitting in a pool of coolant, which I cleaned up. I noticed that the Coolant Recovery Tank was completely full to the brim. I finished changing the oil and started it up to run for about 15 minutes. Ran beautifully and within temp range! Opened up the compartment, and once again, coolant -- everywhere! What in the world, everything looks completely normal. Anyone have any idea what might be happening or what the problem might be?

You didn't say whether you emptied the full overflow reservoir before starting up the generator again. If you didn't do that the next time you start the generator the coolant will overflow since it has no place to go. The idea is that the generator will put coolant into the overflow while it heats up and then the coolant will go back into the generator as it cools down....but over time the reservior will fill up.

[tanglewood]

Check the condition of the tube/hose that runs from the heat exchanger coolant cap over to the overflow bottle. Mine had completely rotted out after only 2 years. The result was a bunch of coolant in the pan under the genset. But I'm not sure how to explain the seemingly excess coolant in the overflow bottle. I agree with the suggestion to pull the covers off and sit there and watch the thing run as it warms up to see where the leak is coming from.

[Paradise1]

Originally Posted by DougR

The heat exchanger tank contains the HE element, and the element sticks out of the tank at each end. The sea water flows thru the inside of the tubes in the element, and the antifreeze surrounds the tubes on the outside of the tubes within the tank. On each end of the element are rubber end caps that clamp both to a flange on the tank and also to the body of the element. These caps locate the element within the tank. There are two large hose clamps on each end of the heat exchanger. The clamp closest to the HE tank clamps onto the tank flange, and the slightly smaller clamp squeezes onto the body of the element. So coolant resides in the tank and can flow slightly between the gap of the tank and the element, but then is stopped from moving further by the clamp further away from the tank.

Seawater flows from the pump to the end of the rubber cap and then into the HE element. The only thing that stops the mixing of coolant and sea water is the pressure of the second clamp squeezing the rubber cap against the body of the HE element, so if that clamp is loose there can be some seawater forced into the coolant.

This is a little difficult to describe, but if you look at the parts breakdown on the Northern Lights website it may become clear to you. The same system is used on the Volvo Penta 2020, 2030, etc. engines as well as other Bowman coolers so you may find a parts breakdown in several places.

Hope this is helpful.

DougR

DougR was 100% right!! While I thought the clamps were tight, not finding a solution, I really tightened them all again - super tight! The coolant stopped coming out of the overflow tube!!! I flushed all the sea water and coolant out of the system with pure water, draining completely and then filled with new coolant. Just ran for 30 minutes. All perfect!!! Thank you DougR!!!!

[onewadd]

Paradise, you may want to replace the boots on either end of the heat exchanger first chance you get. Hose clamps can (like all fasteners) be over torqued which will end in an inconvenient failure. If you needed to tighten them "super tight" then likely they are near the end of life. Rubber gets soft over time and will fail. Just a thought.