Onan 9.5kva Generator

[Nick Epps]

Hi all,
I'm new to the site and new to boating (well within the last 40 years post kids etc) and purchased a lovely Fairline T44 GT last year. Since purchase I've been busy doing lot of small repair's and replacing the side step teak decks, so I'm pretty handy and will tackle most things with the aid of utube. One silly question I have the above geni, and when its running (serviced recently with a new water pump) it doesn't spit out any water which is kinda what I was expecting....Am I missing something??
This is Zen, based in Portals Mallorca...just loving her!!

 

[harvey38]

Nice boat, where is the exhaust outlet located?

Some are below the waterline so you won't see much but you should hear/see a burble as the exhaust gasses surface.

 

[volvopaul]

It won’t spit water out the exhaust because it has a gas water separator.

 

[Portofino]

On a Sunseeker i once had the separator was plumbed with the water higher and gas below the WL .
Did not think much of it as OEM .One anchorage in the Calanques ( near Marseille ) there were zero services .Running the geny the water trickle and gas burble echoed around the cliff walls .
So in the ER I just reversed the pipes through the relevant TTH cocked fittings .

Now the water was running out below the WL = no trickle and the gas above = no bubbling .
The geny also had a silent running kit .

Shut the complaint yachties up !

So if it bothers you you might be able to reverse yours ……get a water trickle + bubble burgle.
Remember the genys exhaust manifold will have a temp guard on it and they tend to auto shut down if waters not flowing .

Having said that personally I prefer to be able to hear or at least see a reassuring trickle when the geny is running .
Same with the Aircon . You can relax then , you know it ain’t gonna alarm off .

I have seen some boats without under water exhausts water quietly running out of a main engine exhaust hole in the transom .No sound but you can eyeball something.

 

[Hurricane]

Adding to Volvopaul's post.
Check that the water pump isn't getting too hot to touch. As long as it feels cool you should be ok. Mine has a raw water strainer with a clear top so I can see water flowing.
The big issue with Onan generators is the heat exchanges. They only last about 7 or 8 years before they fur up.
It sounds as though you are good at doing stuff yourself so changing the heat exchanger is something you can do yourself with some preparation and research. But if the water pump is cool whilst running, you will be ok fo a while.
But I recommend that you get a spare heat exchanger. I replaced ours and the cleaned the old one up which is now my spare.

Another thing I do. I use a Jabsco sea water impeller instead of the original Onan one. The Jabsco part is a lot cheaper and made from a longer lasting compound rather than the rubber of the original part.

 

[Nick Epps]

Nice boat, where is the exhaust outlet located?

Some are below the waterline so you won't see much but you should hear/see a burble as the exhaust gasses surface.

Thank you. The exhaust outlet is above the waterline. It looks like the water is exited below the waterline…

 

[Nick Epps]

On a Sunseeker i once had the separator was plumbed with the water higher and gas below the WL .
Did not think much of it as OEM .One anchorage in the Calanques ( near Marseille ) there were zero services .Running the geny the water trickle and gas burble echoed around the cliff walls .
So in the ER I just reversed the pipes through the relevant TTH cocked fittings .

Now the water was running out below the WL = no trickle and the gas above = no bubbling .
The geny also had a silent running kit .

Shut the complaint yachties up !

So if it bothers you you might be able to reverse yours ……get a water trickle + bubble burgle.
Remember the genys exhaust manifold will have a temp guard on it and they tend to auto shut down if waters not flowing .

Having said that personally I prefer to be able to hear or at least see a reassuring trickle when the geny is running .
Same with the Aircon . You can relax then , you know it ain’t gonna alarm off .

I have seen some boats without under water exhausts water quietly running out of a main engine exhaust hole in the transom .No sound but you can eyeball something.

Thank you Portofino…. Comprehensive reply. Really helpful indeed…. That’s exactly my issue, being able to eyeball something as an indicator that all is well….

 

[Nick Epps]

It won’t spit water out the exhaust because it has a gas water separator.

I wouldn’t have thought of that. Thanks

 

[Nick Epps]

Adding to Volvopaul's post.
Check that the water pump isn't getting too hot to touch. As long as it feels cool you should be ok. Mine has a raw water strainer with a clear top so I can see water flowing.
The big issue with Onan generators is the heat exchanges. They only last about 7 or 8 years before they fur up.
It sounds as though you are good at doing stuff yourself so changing the heat exchanger is something you can do yourself with some preparation and research. But if the water pump is cool whilst running, you will be ok fo a while.
But I recommend that you get a spare heat exchanger. I replaced ours and the cleaned the old one up which is now my spare.

Another thing I do. I use a Jabsco sea water impeller instead of the original Onan one. The Jabsco part is a lot cheaper and made from a longer lasting compound rather than the rubber of the original part.

Good tips… I’ll check that. Also I’ll have a look at the heat exchanger too. Many thanks

 

[Hurricane]

This was my heat exchanger after 8 years.
The hole at the top right was completely blocked. I soaked it in a bucket of Aguafuerte which is an acid that you. can buy in the supermarkets in Spain. Aguafuerte thoroughly cleaned it.


Actually, Aguafuerte is good for cleaning anything calcium based. Removes barnacles as well. We use it to clean all the underwater metalwork - props, rudders, shafts, P brackets and trim tabs etc.

 

[Nick Epps]

This was my heat exchanger after 8 years.
The hole at the top right was completely blocked. I soaked it in a bucket of Aguafuerte which is an acid that you. can buy in the supermarkets in Spain. Aguafuerte thoroughly cleaned it.
View attachment 134663

Actually, Aguafuerte is good for cleaning anything calcium based. Removes barnacles as well. We use it to clean all the underwater metalwork - props, rudders, shafts, P brackets and trim tabs etc.

thanks for the tip....

 

[markc]

This was my heat exchanger after 8 years.
The hole at the top right was completely blocked. I soaked it in a bucket of Aguafuerte which is an acid that you. can buy in the supermarkets in Spain. Aguafuerte thoroughly cleaned it.


Actually, Aguafuerte is good for cleaning anything calcium based. Removes barnacles as well. We use it to clean all the underwater metalwork - props, rudders, shafts, P brackets and trim tabs etc.

Apart for the need to clean periodically what's the life of the actual heat exchanger - i.e. is it worth carrying a £750 spare on the boat?

 

[Portofino]

Apart for the need to clean parodically what's the life of the actual heat exchanger - i.e. is it worth carrying a £750 spare on the boat?

Two pencil anodes there mark on the pic still bolted in while it’s in the bucket .

They are about €10 .The onan ones are identical ( common cross part ) to one on my MASE air water cooler .
Replace regularly.It’s corrosion that accelerates the demise .
I ,am still on my original 2001 cooler .
Rydlimed it once FWIW ? Wasn’t blocked just fancied more time in my man cave .

 

[Forty_Two]

I have the Onan 11kva which is the same physical as 9.5kva.

Installed in 2002 i carry a spare raw pump & heat exchanger. Had ro replace the original raw pump after 16 years due ro corrosion on the body. Had to replace original heat exchanger after 18 years due to difficulty getting a reliable seal on one end cap even with new gasket & end cap.

I have found they block mainly at the anode end & swopped them over every 2/3 years & took the blocked one home to re-furb.

Having a spare heat exchanger is great if you have a problem during the season as by clamping the raw water hoses you can do a change in an hour, no interruption to the cruise.

That can be avoided if you remove both end caps annually & use an enderscope camera to check the condition. Luckily Onan sell the end cap seal seperately so this is a nice low cost check if you don't fancy carring a spare unit.

 

[Hurricane]

Apart for the need to clean periodically what's the life of the actual heat exchanger - i.e. is it worth carrying a £750 spare on the boat?

When I bought my spare heat exchanger, I didn't have the luxury of knowing that the old one could be cleaned. If you search these forums, you will see that people have been replacing heat exchanges after about 7 years.
I did my own replacement and, knowing what I know now, it ought to be possible to remove and clean one without replacing. But I left my old heat exchanger in a bucket of acid for about a day to be sure that all the waterways were clear. And I haven't yet put the old one back although it does look in good condition.
I think a spare would be a good idea though.

 

[markc]

When I bought my spare heat exchanger, I didn't have the luxury of knowing that the old one could be cleaned. If you search these forums, you will see that people have been replacing heat exchanges after about 7 years.
I did my own replacement and, knowing what I know now, it ought to be possible to remove and clean one without replacing. But I left my old heat exchanger in a bucket of acid for about a day to be sure that all the waterways were clear. And I haven't yet put the old one back although it does look in good condition.
I think a spare would be a good idea though.

Thanks! I think I'll take it off when I'm there in a couple of weeks and take a view. I did find a non OEM one for £300 but it's in the US and after shipping and taxes it's close to 1k!