Practicalities of converting to closed cooling system

[realslimshady]

I've just fitted a 300hr AQ225D into my weekender to replace the original knackered 200D.
Although it's a 1982 engine, with so few hours on it, it looks in really good nick outside and inside the rocker covers, at least.
It was suggested that going to freshwater cooling would be a good way of extending its life, and I must say I like the idea of it not sitting full of salt water all the time-so, does anyone have any experience of this conversion, would it be worth the effort, is there anywhere one can buy a 'kit' to do this, any ideas of cost, will it improve engine efficiency by allowing it to run hotter....
Any views welcome.

 

[spannerman]

I must say I think you are being very optimistic with an engine that old. Although its only done 300 hrs, its had 27 yrs of saltwater sitting in it, the problem is with these engines is the water passages between the head and block erode and get bigger until they are a larger diameter than the crush ring in the gasket so it no longers seals and water can get into the engine, they really are a ticking bomb at that age. The only way to be sure is pull the heads and check the corrosion before splashing out on freshwater cooling conversion.
The manifolds will probably need replacing anytime soon if its not been done very recently.
Sorry to be pessimistic but don't want to se you throw good money away.
It may be more cost effective to get a newer V8 block and heads from a car which has automatically only been run with freshwater/antifreeze and swap the relevant bits over inc the camshaft as this delivers the power in a different rev range to a road cam.
This way you know the engine is sound and will have years of life in it.

 

[kashurst]

rather than go to all the expense and trouble of creating a fresh water cooling system, why not just fit some extra plumbing at the sea water inlet so you can put a hose pipe onto it and flush the engine with fresh water after use.

 

[Juggler7823]

Not a good idea!

Putting a hose pipe onto a cooling system is not a good idea. Its is only designed for a few psi .

why not just fit some extra plumbing at the sea water inlet so you can put a hose pipe onto it and flush the engine with fresh water after use.

 

[realslimshady]

Putting a hose pipe onto a cooling system is not a good idea. Its is only designed for a few psi .

and a bit awkward on a swinging mooring.....
I am encouraged by the fact that-allegedly-the engine came from a German Navy fast patrol boat which spent most of its time out of the water, with a complete log of hours run dates and times etc...so I don't think it has sat in saltwater for suuuuuch a long time. Or I may be being overly optimistic!

 

[ontheplane]

Hiya,

Can I ask you what the job was like difficulty-wise??

As you may have seen from a prev post, a friend has same boat and wants a re-engine! I am not sure of viability, hence asking what costs etc were.