Onan heat exchanger

[boaterholic]

I have a 9kw onan I need to replace end cap and seals on one end of heat exchanger. Do I need to drain it before opening the end cap?
Do I need to clamp off the coolant lines before removing the end cap or does coolant stay captive and only the raw water will drain out?
Thank you!

 

[Irie308]

I have a 9kw onan I need to replace end cap and seals on one end of heat exchanger. Do I need to drain it before opening the end cap?
Do I need to clamp off the coolant lines before removing the end cap or does coolant stay captive and only the raw water will drain out?
Thank you!

Looking to do this over the winter. Pretty sure you’ll have to drain the coolant prior to removing. That cooler is filled with coolant. My plan is to removed the entire cooler. Were you able to source the seals? I haven’t looked yet.

 

[boaterholic]

Looking to do this over the winter. Pretty sure you’ll have to drain the coolant prior to removing. That cooler is filled with coolant. My plan is to removed the entire cooler. Were you able to source the seals? I haven’t looked yet.

Yes I have 2 seal kits that include end caps, o-ring for the bolt, and gasket for the caps.
I was not planing to remove the exchanger and hoping the coolant was captive within the plumbing of the heat exchanger such that if I didn’t remove the coolant hoses the coolant would remain trapped if I only removed the end cap needing new seals.

here is link to seal kits I ordered.

Onan 0130-5176 Cap Kit-Heat Exch Cummins Genuine OEM https://www.amazon.com/dp/B0753L24K...abc_4877HFQ87P32TH7Q6RFJ?_encoding=UTF8&psc=1

 

[alnav]

If you are only replacing the end caps, you should be fine. The coolant will not be compromised, just the raw water. If you pull the zinc, most all the raw water will drain out. It only amounts to a gallon or so if that. You can also take a wet-dry vac to the strainer and remove most of the raw water from there before pulling the zinc or the end caps.

 

[ttmott]

Yes, the coolant loop is isolated from the end caps which are raw water only; at least true on my MDKBN Onan.

 

[Irie308]

Yes I have 2 seal kits that include end caps, o-ring for the bolt, and gasket for the caps.
I was not planing to remove the exchanger and hoping the coolant was captive within the plumbing of the heat exchanger such that if I didn’t remove the coolant hoses the coolant would remain trapped if I only removed the end cap needing new seals.

here is link to seal kits I ordered.

Onan 0130-5176 Cap Kit-Heat Exch Cummins Genuine OEM https://www.amazon.com/dp/B0753L24K...abc_4877HFQ87P32TH7Q6RFJ?_encoding=UTF8&psc=1

Yup, as stated ,if you’re leaving in place the coolant will be fine. Report back how your project goes. I’d rather leave in place as well and not have to pull the cooler. Looking at it seemed there was no room to work with the sound shield.

 

[boaterholic]

Ok thanks guys!
Irie, the end cap I’ll be working on is aft facing one and easy to get to by removing the rear sound shield panel. I had them off today to replace the v-belt and it’s easy to get to.

 

[b_arrington]

I have an MDKDL 9kWH model with sound shield. The front panel is easy to remove. The side panel seems much more involved, with bolts along the inside bottom edge. How hard / easy is the side panel to get off, and any tips?

 

[boaterholic]

I have an MDKDL 9kWH model with sound shield. The front panel is easy to remove. The side panel seems much more involved, with bolts along the inside bottom edge. How hard / easy is the side panel to get off, and any tips?

My MDKAV setup sounds the same as yours, and for my endocarp change I won't need to remove the side panel. But best I can tell when I was looking at it appears you will need a small wrench on the nuts inside the side panels and a second wrench on the top and bottoms for the bolt heads. I would use a ratcheting wrench if you can get it to fit on the tops and bottoms to speed up removal.

 

[b_arrington]

My MDKAV setup sounds the same as yours, and for my endocarp change I won't need to remove the side panel. But best I can tell when I was looking at it appears you will need a small wrench on the nuts inside the side panels and a second wrench on the top and bottoms for the bolt heads. I would use a ratcheting wrench if you can get it to fit on the tops and bottoms to speed up removal.

My genset is on a shelf on the port side. There's no way to get to the back of the heat exchanger without removing the end cap.

On the front side, it MIGHT be possible to get to the front cap. However, the oil filter is right in front of it. I'm not sure that I would be able to get a socket in there to open it up. Best plan, if need be, would be to take of the side panel.