More Nanni cooling woes. Repair or replace engine?

[tean]

Back in the winter I posted on here about my Nanni engine and its apparent inability to warm up properly. Well in the warmer summer seawater things have improved a bit and it has been managing to get to about 70 degrees if worked reasonably hard. A quick twenty minutes at anchor to get some hot water is a non-starter though.

Now though the engine seems to have taken offence at my criticism of its underheating and has gone to the other extreme, overheating. The cause is the heat exchanger casting which has corroded through, allowing the coolant to escape into the exhaust.

The cost of a new heat exchanger is a bit over £600, and that's just the bare casting. I know the tube stack is seized in the old casting and if it won't come out intact then that's another £300, although presumably as the casting will be scrap I can just cut it away to release the tube stack without stressing it too much. So with a few gaskets I'm looking at either about £700 or £1000 to repair the engine.

Or I can pull the whole thing out and replace it with a Beta 14 which should fit onto my gearbox for about £3000.

So which to do?

The existing engine has only 800 hours on it and seems to be absolutely fine other than the rotten cooling system, so it might seem like overkill to replace it, but I am considering selling the boat after this season and am wondering what effect a shiny new engine would have on its value. It's a Hunter Pilot which is in really nice condition with a great inventory and should be worth the top end the price range, maybe £25,000. If a new engine could raise that to perhaps anywhere over £27,000 then I break even over repairing the old one.

Decisions decisions. Any comments appreciated.

 

[No Regrets]

I would look at replacing the heat exchanger.

Soaking the whole lot in a suitable acid will free the stack for removal, just be patient!

 

[sailorman]

I would look at replacing the heat exchanger.

Soaking the whole lot in a suitable acid will free the stack for removal, just be patient!

Get the HE order in fast as the French will soon be on holiday

 

[cindersailor]

I would say that the difference in sale price between a boat with 800 hrs on the engine and a new one would not make up for the additional £2k. I am surprised that the heat exchanger has given up after only 800 hrs, although I suppose the age of the engine would also be a factor. The Betas are nice engines; I have a 10 year old 16 with about 1500 hrs on the clock and little evidence of corrosion in the HE casing or tube stack - it gets a new anode every season whether it needs it or not! I remember reading somewhere when I was making the decision that the smaller Betas and Nannis are effectively the same engines, but that the marinisation is better on the Nanni, which I interpreted to mean principally the heat exchanger, so your experience is surprising. I went for the Beta based on price and reputation for support.

Additional thought: if you do need to replace the tube stack too it is possible that a new Beta HE would be cheaper and fit OK - the base engine will be the same.

 

[tean]

Yes, the small Betas and Nannis are both based on the Kubota Z482 engine (I have a digger that has the same one too) which is why I think it would be very easy to change. The Nanni has to come out anyway to get the heat exchanger off because it's fitted on long studs and there's insufficient room in the boat to slide it off. I've fitted a couple of Betas into friends' boats and have been impressed at how sweetly they ran, but I have no long term experience of them. I am very unimpressed by the marinisation of the Nanni. I can see from the receipts that came with the boat that the cooling system has been repaired a lot and all the pages of the service manual that relate to the cooling are covered in dirty fingermarks and noted part numbers etc. I think I've decided that I don't like it and want to get rid of it, but that's perhaps a rather emotional rather than logical course of action.

 

[pvb]

Yes, the small Betas and Nannis are both based on the Kubota Z482 engine (I have a digger that has the same one too) which is why I think it would be very easy to change. The Nanni has to come out anyway to get the heat exchanger off because it's fitted on long studs and there's insufficient room in the boat to slide it off. I've fitted a couple of Betas into friends' boats and have been impressed at how sweetly they ran, but I have no long term experience of them. I am very unimpressed by the marinisation of the Nanni. I can see from the receipts that came with the boat that the cooling system has been repaired a lot and all the pages of the service manual that relate to the cooling are covered in dirty fingermarks and noted part numbers etc. I think I've decided that I don't like it and want to get rid of it, but that's perhaps a rather emotional rather than logical course of action.

I think you already know the answer to your question!