emergency conversion fresh water pump to raw water?

[Russian007]

Your water pump craps out on the edge of the world, what to do? anyone have experience converting on the fly to pure raw water cooling?

[rslifkin]

If you're talking about converting a closed cooling engine to open cooling, you'd have some significant re-plumbing to do. On many engines, the coolant circulating pump is still needed even with a raw water setup (or you'd need to make further changes to avoid needing it). And then you'd have a salt contaminated engine when you're done, plus depending on what temperature the engine runs (unless you remove the thermostat) you may get massive amounts of salt buildup in the block and heads. Depending on the metals exposed to coolant you could end up with major corrosion too. Either one could be bad enough to require major work afterward (or worse).



Basically, this is just not feasible. With appropriate spare parts, etc. there's not going to be a cooling system failure that you could just easily band-aid by switching to raw water cooling.

[capt jgw]

It would depend on the engine. I once had an old Albin AD2 diesel that had fresh water cooling as an optional add on. When the hx started leaking I converted it back to raw water, I think I had to move two hoses. I doubt any other make would be that easy and others might not be possible at all.

[Russian007]

Originally Posted by capt jgw

It would depend on the engine. I once had an old Albin AD2 diesel that had fresh water cooling as an optional add on. When the hx started leaking I converted it back to raw water, I think I had to move two hoses. I doubt any other make would be that easy and others might not be possible at all.

My 3cyl Volvo 2000 series also seems quite easy to convert. Move a few hoses. In fact some versions come from the factory as raw water only.

[rslifkin]

Originally Posted by Russian007

My 3cyl Volvo 2000 series also seems quite easy to convert. Move a few hoses. In fact some versions come from the factory as raw water only.

That does make it easier. But I can't think of many sudden failure scenarios that you could resolve by just converting to raw water. Plus the downsides of now having run salt water through the engine. Personally, I'm against raw water cooling to the extent that I refuse to own an engine with it and consider any engine that's been run that way as scrap.

[Russian007]

Originally Posted by rslifkin

That does make it easier. But I can't think of many sudden failure scenarios that you could resolve by just converting to raw water. Plus the downsides of now having run salt water through the engine. Personally, I'm against raw water cooling to the extent that I refuse to own an engine with it and consider any engine that's been run that way as scrap.

I don't like salt water in my engine either but engines are easy to flush. We're talking Get-me-home situations here.

[Pete7]

Originally Posted by rslifkin

That does make it easier. But I can't think of many sudden failure scenarios that you could resolve by just converting to raw water. Plus the downsides of now having run salt water through the engine.

Have a read of Russian recent threads to give one example. Whether you could do this at sea without prior planning is difficult to answer without studying the engine, but it might be possible.

Our VP 2003 is raw water cooled, one of the last engines to be built as a RW cooled engine

[Russian007]

Originally Posted by Pete7

Have a read of Russian recent threads to give one example. Whether you could do this at sea without prior planning is difficult to answer without studying the engine, but it might be possible.

Our VP 2003 is raw water cooled, one of the last engines to be built as a RW cooled engine

I think that's the trick. Pre-plumb it. Throw a gate valve and youre back in business. I had a boat with a back up fuel filter system like that.

[deblen]

If you convert to raw water,you should change,or possibly remove,the thermostat. They use a different thermostat for raw. I will try to find the write up on 2003 cooling & send it to you. / Len

[Pete7]

Originally Posted by deblen

If you convert to raw water,you should change,or possibly remove,the thermostat. They use a different thermostat for raw. I will try to find the write up on 2003 cooling & send it to you. / Len

Yes, something like raw is 68c and fresh is 74c from memory but do check. There is also an anode in the RW cooled version behind the alternator and of course a smaller fan belt.

[deblen]

The t-stats are different design,as well as diff temps. On a fresh water cooled,you must allow raw water to flow to the exhaust all the time,but block raw water to the heat exchanger? until the engine warms up-something like that. There is a second "valve plate" in the FW t-stat.
Here is some info I got from a post by Doug R about t-stats some time ago.
Plug T-stat bypass Test.PNG Views: 41 Size: 23.5 KB ID: 265583" style="margin: 2px" />








Edit to show link: https://www.cruisersforum.com/forums...-150137-2.html

[rslifkin]

Originally Posted by Russian007

I think that's the trick. Pre-plumb it. Throw a gate valve and youre back in business. I had a boat with a back up fuel filter system like that.

It's not that simple. On my engines, you'd have to make a few plumbing changes, but more importantly, unless the heat exchanger literally blew up, I can't think of anything that could fail where just switching to raw water cooling would actually help the situation.

[Patrick of M]

I think theoretically many engines would be convertible, but honestly, carrying a spare water pump sounds like a simpler solution.

[deblen]

Some more info & diagrams.Attachment 265598

Attachment 265599


I have 2 more JPGs-112kb & 127kb-showing FW & RW version flow diagrams,but I can't Insert them. I am instructed to Remove? for some reason.


Calorifier installation – Cox Engineering

[deblen]

It appears you could convert to emergency RW cooling by:
1. Run hose from RW pump outlet to lower front cyl. head inlet.
2.Plug upper front cyl head outlet golng to circ.pump.
3.Run a hose from rear t-stat housing outlet to front exhaust ell inlet.Put a tee near the exhaust ell inlet & connect this to the un-blocked outlet at rear of cyl.head.
4. Change to RW type thermostat.
5. plug the header tank small hose at t-stat.

6.Consider installing a zinc anode in block if you convert long term.
7.Make sure you have a good RW filter.


Not 100% sure of the above......