NL M844* HE Cleaning?

[MVCaprice]

Has anyone figured out the easiest way to clean out the HE on their Northern Lights 16-20k 844 based gensets? It looks like the HE is soldered into the exhaust manifold so it needs to be removed in one piece.

The temps have been creeping up a bit and I want to give it a HCL/Oxacylic flush to clean it up but am going back and forth whether i want to pull the entire manifold off or do it in place. Luckily I have easy access to the non service side of the genset which I can say is a huge benefit of having the genny in the engine room where it lives.

What have y'all done to clean your generator HEs?

 

[Colwyn D]

Does it have the rubber caps either end of the h/e jubilee clipped in place. If so the tube h/e bundle slides out.
I clean mine by removing and submerging in a bath of phosphoric acid, cheap plastic container.

 

[MVCaprice]

Yes it has the rubber caps. I guess i didn't realize the he tube comes out that easily. That is awesome!

 

[MVCaprice]

You sir were spot on. I pulled the HE out from the generator unit side. I had to drain the coolant obviously as well as move the relay housing that sits on top of the genpack out of the way. The HE was partially obstructed with impeller bits from some time ago which was easily fixed. I am going to dunk/flush with HCL/Oxalic mix and reinstall. I am wondering whether the inside of the HE on the freshwater side is sludgy. Also worth noting is that I have read that the right way to install it is by tightening the smaller boots first so there is no saltwater seal leaks so I will do that when i reinstall.

One other thing that peaked my interest was the existence of a couple inch or so round holes on one side of the tube and what looks like an air vent hole on the opposite side itself. Does anyone have any info on the clocking of those holes? I assume the small hole is on top, but i figured I would ask before i call NL to confirm.

 

[racclarkson@gmail.com]

Best to pick up a couple of those rubber boots. They are fragile and easy to knick or cut with the hose clamps.

 

[MVCaprice]

Best to pick up a couple of those rubber boots. They are fragile and easy to knick or cut with the hose clamps.

That's good advise. Ours are fresh as of ~2013 and they don't look too bad luckily.

 

[Colwyn D]

Yes, little hole on top.

 

[MVCaprice]

Yes, little hole on top.

I just heard back from NL and they said that the large holes go on the top.

 

[Colwyn D]

Thanks for passing that on. Always thought small holes were air vents and large hole that lines up with coolant hose would allow flow through the bundle.
If they have definitely confirmed it's otherwise I'll spin mine around.

 

[MVCaprice]

They really should add this to their schematics....along with color coding of wires.

 

[Colwyn D]

This yanmar service advisory doc has it the other way.

As you say, should be in the manual.

 

[MVCaprice]

Apparently I misunderstood. “Small vent holes up, big holes down”