Re-Plumbing to Get Fresh Water Cooling

[BillS]

I have an 1154 Universal – they were sea water cooled and this one has a bad block. I found a Z600 block which I am told is the same as the Z500, the Kubota base block on the 1154. Here is my thoughts – I want to fresh water cool if I can and I can’t find a traditional manifold/reservoir (it would have to be a M18 manifold) so, what I think I’ll do is to re-plumb. A small hose now comes from the water exit on the engine and enters the top of the manifold (I assume it has water passages) – I’ll instead feed this manifold (the existing Universal 299178 raw water manifold) from a tee off the sea water pump. Then I can take the water exit on the engine and devise an exchanger and reservoir mounted on the front, back or on a bulkhead, fed by a pump circulating water/antifreeze through the engine with the other tap on the sea water pump tee providing cooling to the exchanger. Has anyone had any experience this way?

Also I have a lot of Petter AC2W parts that I’ll put on classifieds

[MitchM]

what an interesting project! if the raw water flow through the block is properly sized to remove sufficient heat without an antifreeze freshwater cooling circuit, adding a freshwater heat removal system will make your engine run cooler. is t hat a good idea? maybe i am missing something, but where and how is the new raw water going to mix with the hot exhaust gases to cool the exhaust gases in your new system ? and how are you going to make the existing raw water loop which presently blows raw water out thru the mix elbow into a closed system so no antifreeze ever escapes? engine mfgrs sized the raw water flow to adequately cool the hot exhaust gases at all rpms without additional heat loss to an antifreeze fresh water system.. in your old system the raw water mixes with the exhuast gases to cool them so you dont fry your exhuast hoses. in your new system you'd also have to remove the waste heat from the exhaust gases to keep from frying your exhaust system. check the gpm flow of your raw water pump, you'd have to replicate this to get adequate raw water flow to cool the exhaust gases in the mixing elbow. most freshwater pumps are gear drive off the engine. how will you drive your new freshwater pump? and key it to engine rpms? the key to the whole new design is an adequate exchange of heat between the new hot antifreeze which is pulling heat load off the engine block , then giving that heat to the colder raw water flowing past in the new heat exchanger. the new raw water pump system has to be of sufficient volume at any rpm to remove enough heat to keep the antifreeze from boiling in your fresh water system, and the raw water must also have sufficient capacity after absorbing the antifreeze heat to cool the exhaust gases in the mix elbow. the counterflow jacketed tube-style heat exchangers on marine diesels aren't that large. wonder if you could find a large used counterflow marine heat exchanger to rig into your system to simplify matters. you'd really have to have bomb-proof seals to keep the antifreeze from mixing into the raw water in the counterflow heat exchanger or you'd have problems. knowing the seawater inlet temp, the gpm raw water flow , and assuming the exhaust gas temp and flow rates would allow an engineer to calculate the sizes for the pipes to and from the jacketed heat exchanger . (a pretty complicated problem..) is your raw water pump a belt drive or a gear drive ? and how would you rig up the engine block thermostat which now would be fed with antifreeze...?
wouldn't it be simpler to just add a nonsalt water flush to your existing raw water pump system to keep salt from building up inside the engine ?
to be on the safe side i'd add a Borel exhaust temp alarm to your eventual system if your engine doesn't have a mount for a high temp alarm....
keep us posted, it's sure an interesting project...

[BillS]

answer to question 1 - could be after raw water goes though the exchanger it enters the exhaust manifold to cool exhaust or a tee could be put in after the raw pump running some water to the exchanger and some to the exhaust manifold - most likely the tee. question 2 - the raw water after leaving the exchanger would go out as usual though the riser after the manifold, before the water lift muffler. question 3 - the raw water and water in the anti-freeze loop never contact one another - the exchanger is a pretty common item, I am not sure I can find one with a reservoir and cap, and like a car I would have to have an overflow plastic tank. question 4 - I don't doubt the exhaust will work, as it isn't much different then the original and still raw water - it is the flow through the engine and if I should leave the thermostat where it is on the manifold or incorperate it is the anti-freeze loop side of the exchanger like a car - I think I'll have to do the latter. question 4 - the second pump (which becomes the raw and which the anti-freeze loop will need to be decided) will have to be belt driven. - the key I think is the be sure the exchanger is over sized - I little over-kill here is good.

I think I covered most of what you brought up - I used to have a boat with a 4-107 fresh water cooled and after catastrophic cooling failure with a raw water cooled 5411 block, even in the upper Chesapeake which seldom sees salt, I want fresh water cooling if i can work it. On a note the engine that was suppose to be a Z600 turned out the other day to be a D600 (3 cyl), so I am still looking for a Z500 or Z600 (Z stands for 2 cyl and the Kubota Z500/Z600 fits may existing marinarzing bell housing and manifold). If I can get an engine together, I will bench test during the winter, working out kinks before it sees the boat.

[never monday]

how will you pump coolant?
what will you do with the thermostat now in the system?