[gbgreen59]

I have a Volvo MD11D 25 HP diesel engine. The year of the boat is 1984. The engine currently uses raw water for cooling. With the boat being on fresh water, this has not been a problem up to this point in time. I plan to move the boat to salt water in 2 or three years, so I would like to convert the cooling system to a the "closed loop" type.

I've done a little poking around the web and found a couple of places that sell kits, but maybe not a kit for this model of engine. So, they would need to assemble a kit for this engine. I've considered doing the work myself, which would consist of picking a heat exchanger, having mounting brackets made for the various parts, picking a water pump, etc, etc.

Does anyone have experience making a conversion from raw water cooling to a closed loop cooling system? Any guidance/recommendations on doing the work or having it done would be greatly appreciated.

 

[Faster]

There are at least a couple of outfits in the Bellingham/Seattle area that make small heat exchangers for such a job, SeaKamp engineering being one.

Makes sense, I think, to do this conversion if you are confident that the engine is not already suffering internal corrosion damage, as would be the case with fresh 'raw' water.

Adding a second pump and a way to drive it would seem to be the bigger challenge. IIRC Jabsco makes a pump mount that runs directly off the crankshaft end, avoids belts but you need the space for it.

 

[Delta-T]

My only advice here would be you need to change to zinc anodes for salt water. My original 1968 Bristol Graymarine engine is raw water cooled. Been in the salt water all her life. I rebuilt the engine 13 years ago because of back siphoning from an exhaust failure. Other than some rust sediment the the cooling lower end of the block and a valve job, she was just fine. I have two zinc pencils in the head that I replace every year.

 

[gbgreen59]

I have two zinc pencils in the head that I replace every year.

Not sure what you mean here. Do you mean that the "zinc Pencils" are mounted on the cylinder heads? I've always thought of sacrificial anodes being in the water. Sorry for the lack of understanding on my part.

 

[gbgreen59]

I did a little searching around on the "zinc pencils". I understand now. I'm going to see if my engine has them...it should, since raw water cooled...correct?

Man, what else "don't" I know that could be the most important thing in the world...

 

[Hudsonian]

Consider using an electric pump to circulate the coolth; they're kits built with reservoirs. This arrangement eliminates adding another pulley and mounting and alignment problems.

Consider mounting the heat exchanger off the engine; perhaps on a nearby bulkhead, if it would ease service. The heat exchanger itself will have a zinc pencil in addition to those on the engine; these need to be replaced annually.

Once you're running a closed systems you can change the thermostat to increase the operating temp of the engine, thereby, increasing engine efficiency.

 

[JimsCAL]

There are kits made for the Atomic 4 that can be used on small diesels. Check Moyer Marine and Indigo Electronics. Here's one with an electric pump that should work on just about any engine.

Atomic 4 Fresh Water Cooling System - Electric Antifreeze Pump

 

[HUGOSALT]

Appreciate not what you are asking...however my 2 cents worth.
Boat has been in fresh water for 30 years, suggest not converting to
closed loop, I would flush with Rydlyme annually, (see Mainesails instructions), locate and change engine zincs often, make sure thermostat is correct one for salt water cooled (lower temp) and enjoy for next 20 odd years.
My 1985 Yanmar 3GM, raw water cooled, has been in salt water for 30 years and
have followed above (along with not idling for long periods and always winterizing
with non-corrosive anti freeze...never leaving over winter drained dry) and
upon inspection last year water jackets/exhaust manifold still looking newish.
No experience with your Volvo motor, but again just my 2 cents worth.

 

[Delta-T]

I did a little searching around on the "zinc pencils". I understand now. I'm going to see if my engine has them...it should, since raw water cooled...correct?

Man, what else "don't" I know that could be the most important thing in the world...

My understanding there is a different type of anode used for fresh water. I assumed you are using a magnesium anode that is for fresh water?

 

[Delta-T]

One other small tip: I had issues for years with my water pump bearings and seals not lasting more than two years. I finally took maters in my own hands and found that I was being supplies seals with housings made of steel, and not even coated steel! I was able to get full encapsulated seals with the rubber lip material covering the housing. No problems since the upgrade. Point being, you might want to rebuild you pump with salt water rated seals and SS bearings.

 

[capta]

I don't know this particular engine, but doesn't Volvo sell this engine with a pump and heat exchanger? If so, get the pump and heat exchanger specs (flow rates and port sizes) from Volvo and go to a pump supply house for the pump and maybe even the brackets. Same with an aftermarket equivalent for heat exchanger and header tank.
If worse comes to worse, you'll have to fork out for the Volvo brackets, but unless you've a shop and the skill, custom brackets may be more than stock Volvo, and you don't have to measure anything and they should come painted.
But you'd save plenty on the pump and heat exchanger.
Depco Pump Company
PumpAgents.com - Pump Sellers
PumpVendor is Your Source for Marine Pumps, Industrial Pumps and Pump Parts

 

[Capt Len]

Some manifolds have the expansion tank built in. If this is so, the heat exchange is mounted low so it fills to the high point and no air lock. If sealed manifold, expansion tank,often built into top of exchanger, is highest point and all hoses can burb up .Neglecting to change zincs asking to replace stuff before the failure gets serious. A proper choice and instal of belt driven impeller pump is the usual and can work even if electric power fails. Mount stuff so you can get at the removable ends of the tube.

 

[gbgreen59]

I found schematics for my Volvo engine (MD11D). As a reminder, the engine is raw water cooled as opposed to a closed loop cooling system.

A previous post in the thread mentioned changing "pencil anodes" in the cooling system. From the schematics I found, pencil anodes are not specifically mentioned. The breakout of parts does not seem to show them either. Does this surprise anyone...maybe not all raw water cooled engines have pencil anodes? Maybe I just don't know how to identify them. Do all raw water cooled engines have pencil anodes somewhere?

From what I have found out about raw water cooled engines, it seems that pencil anodes are of primary importance to keep the engine from corroding, especially in salt water. Is this a true statement?

 

[JimsCAL]

Depends on the materials used. Most engines do include anodes (zincs). However my Yanmar 3GM30F does not since the heat exchanger is made with CuNi.

 

[gbgreen59]

Here is what I've been able to find. If you look at the attached figure, the engine diagram shows a plug on top of the heat exchanger. It looks like this is where the anode would go. The parts list on the schematic just calls it a "plug". Nothing identifies it as a sacrificial anode. The online listing, also shown in the attached figure, identifies certain heat exchangers that the anode plug is used. Guess I could pull the current plug on the engine to see what it looks like.

Any ideas or recommendations?

 

[Markwesti]

This is a good Co.SEN-DURE, INC. | Manufacturers of Heat Exchangers and Oil Coolers
And of course you will need another pump . I like this one . http://www.pumpvendor.com/media/jabsco/Jabsco_2760_series.pdf

 

[deniseO30]

I know they make drag.. but I really like the large power boat answer to engine cooling with Keel coolers. basically lots lots less stuff to break. all that is needed is the engine coolant water pump.

 

[PitApe]

I know they make drag.. but I really like the large power boat answer to engine cooling with Keel coolers. basically lots lots less stuff to break. all that is needed is the engine coolant water pump.

You still need to have a SW pump for injecting water into the exhaust, unless you want to have a "dry" exhaust system (which on a sailboat is PITA).

 

[deniseO30]

You still need to have a SW pump for injecting water into the exhaust, unless you want to have a "dry" exhaust system (which on a sailboat is PITA).

And some do have dry exhaust, and no, I don't want to do that on sailboats!

I just like keel coolers