Convert Engines To Closed Cooling System

I believe the full system uses a larger diameter heat exchanger with additional hoses and fittings to connect the heat exchanger to the manifolds. The larger heat exchanger is needed to cool the manifolds in addition to the engine block. In addition you need to add the block off plates and gaskets needed to separate the manifolds from the elbows/risers (if equipped). You can find the diagrams online. Added parts cost probably about $1200 for the heat exchanger and hoses. Sell the take offs to reduce the cost.
 
All,

Thank you for the responses it is greatly appreciated and gives me food for thought before spending money.
 
Hey folks hoping you can help advise me similar thinking on this thread. I just bought a used 2005 Sea Ray 320 with Twin 350 Mercruiser (5.7L) MAG MPI Horizons V drive engines. The port side engine just failed with milky oil and salt water in engine. I ordered 2 new engine cores and we will reuse sea water pumps, alterators and other components. I really wanted to convert the new rebuilt engines over to full fresh water cooled heated exchangers. I have been looking at after market options but am concerned at the idea that the ECM needs to be replaced also. Does anyone have advice on if ECM can be reprogrammed or needs to be replaced? Can anyone comment on aftermarket dealer vs OEM? OEM per engine is $6300 CAD$$. That is about $4000 US per side!! Yes I know I can flush with hose kit everytime but there are times when I will not have a hose around for weeks at a time. Thanks.
 
Never could understand the ECM difference. I converted mine to closed cooled a couple of years ago with no issue at all. Went with a Seacamp exchanger and used all Merc hoses and T-stat housing, runs at 160 same as it was with open cooling.
 
Were your manifolds and risers new at the time of conversion? How old were the engines? Thanks for this info.
 
scoflaw said:
Never could understand the ECM difference. I converted mine to closed cooled a couple of years ago with no issue at all. Went with a Seacamp exchanger and used all Merc hoses and T-stat housing, runs at 160 same as it was with open cooling.
Click to expand...


A quick review of Mercruiser's site shows the same ECM as a part being used on both raw water and closed cooling engines. If there is no operating temp difference.....not sure why somebody would have made this up.
 
speakrdude said:
The difference between the two above phrases are Exhaust manifold and Exhaust elbow. Either and all systems will use the exhaust elbow to "dump" the hot water out the exhaust and to keep the rubber exhaust parts from melting.

When you go "Full" cooled, which is the best if you can, There HAS TO BE a block-off gasket between the exhaust manifold and the exhaust elbow, (AKA riser). This gasket keeps the glycol in the engine AND exhaust manifold, and the hot water through ONLY the Exhaust Elbow.
"Full Cooled" requires an external pump, typically a belt driven or crank-mounted pump.
The Alpha stern drive pump will not support Full-Cooled on it's own, thereby, creating the need for Half-Cooled.

Even Half-Cooled is miles ahead of raw-water cooled, for many reasons. Protects the block and circ pump. Glycol keeps metal parts lubricated and rust free.
Block runs hotter as it was designed to do. Fuel burns more efficiently. No need to drain the block in the winter. Resale value is better. No sand and crude being sucked through your block.

The ONLY reason all MFGs Do Not make it mandatory to be installed, is the few $$ extra it makes the sale price.

Convinced yet?

I install both half and full kits all the time. Let me know if you have any more questions.

Jim
Click to expand...
Xplicitlnck said:
So im changing my manifolds. I currently have a "half" fresh water cooling system. If I wanted to turn that into a "full" system what would I have to do?
Click to expand...
SCORPIO said:
Risers are always raw water cooled as the raw water needs to be discharged somewhere and something is needed to cool the risers, exhaust hoses, elbows etc. Its a fairly easy system to understand once you see one in person. A 'full system' is a far superior way to cool a marine engine than to simply circulate salt water thru the engine block, manifolds and risers. I can't imagine a more corrosive fluid to cool cast iron than hot brine solution.
Click to expand...
well, find yourself a pair of ss risers or 90's what ever you want to call them
 
I looked at Merc's site and 10 different ECM's were used on V8's with a 0W prefix which is what the OP probably has Lot of combo's there. Does he need to change it? Don't know.
 
Mark007 said:
Hey folks hoping you can help advise me similar thinking on this thread. I just bought a used 2005 Sea Ray 320 with Twin 350 Mercruiser (5.7L) MAG MPI Horizons V drive engines. The port side engine just failed with milky oil and salt water in engine. I ordered 2 new engine cores and we will reuse sea water pumps, alterators and other components. I really wanted to convert the new rebuilt engines over to full fresh water cooled heated exchangers. I have been looking at after market options but am concerned at the idea that the ECM needs to be replaced also. Does anyone have advice on if ECM can be reprogrammed or needs to be replaced? Can anyone comment on aftermarket dealer vs OEM? OEM per engine is $6300 CAD$$. That is about $4000 US per side!! Yes I know I can flush with hose kit everytime but there are times when I will not have a hose around for weeks at a time. Thanks.
Click to expand...
I thought the horizons were already set up w/fwc, anyway if you are going the expense of a repower ,positively go w/fwc full and use dry joint exhaust, or try and find a ss riser for the saltwater, and change your coolers (oil and power steering)
 
KEVIN D TOBIN said:
I thought the horizons were already set up w/fwc, anyway if you are going the expense of a repower ,positively go w/fwc full and use dry joint exhaust, or try and find a ss riser for the saltwater, and change your coolers (oil and power steering)
Click to expand...
Thank you for the help. Any ideas on where to get an aftermarket heat exchanger and hoses/thermostat etc?

also where to get dryjoint exhaust?
Ss risers?

please help me understand why to upgrade the oil cooler and is there actual powersteering? (Steering is hydraulic ram). Could a leak in oil cooler allow more salt water in new engine? ie does raw water run through it?
Thanks
 
Mark007 said:
Thank you for the help. Any ideas on where to get an aftermarket heat exchanger and hoses/thermostat etc?

also where to get dryjoint exhaust?
Ss risers?

please help me understand why to upgrade the oil cooler and is there actual powersteering? (Steering is hydraulic ram). Could a leak in oil cooler allow more salt water in new engine? ie does raw water run through it?
Thanks
Click to expand...
I just ordered a fwc system for my 454 from PPT. The only issue is that the system ship date is around two months out. You would have to contact them to get the right system for your power plant.

https://www.perfprotech.com/mercrui...ve-models-full-system-mfh-5374/product/247281

I think the comment about the cooler replacements was due to them having raw water run through them like everything else. I found tiny muscles in some of my parts. Those would be a prime place for salt water corrosion or blockage.
 
speakrdude said:
The difference between the two above phrases are Exhaust manifold and Exhaust elbow. Either and all systems will use the exhaust elbow to "dump" the hot water out the exhaust and to keep the rubber exhaust parts from melting.

When you go "Full" cooled, which is the best if you can, There HAS TO BE a block-off gasket between the exhaust manifold and the exhaust elbow, (AKA riser). This gasket keeps the glycol in the engine AND exhaust manifold, and the hot water through ONLY the Exhaust Elbow.
"Full Cooled" requires an external pump, typically a belt driven or crank-mounted pump.
The Alpha stern drive pump will not support Full-Cooled on it's own, thereby, creating the need for Half-Cooled.

Even Half-Cooled is miles ahead of raw-water cooled, for many reasons. Protects the block and circ pump. Glycol keeps metal parts lubricated and rust free.
Block runs hotter as it was designed to do. Fuel burns more efficiently. No need to drain the block in the winter. Resale value is better. No sand and crude being sucked through your block.

The ONLY reason all MFGs Do Not make it mandatory to be installed, is the few $$ extra it makes the sale price.

Convinced yet?

I install both half and full kits all the time. Let me know if you have any more questions.

Jim
Click to expand...

NewJim, Please contact me at jack.gjovaag@yahoo.com or on FB Messenger (same name) about installing a closed system in my boat, assuming you are still in the business.
 
scoflaw said:
Never could understand the ECM difference. I converted mine to closed cooled a couple of years ago with no issue at all. Went with a Seacamp exchanger and used all Merc hoses and T-stat housing, runs at 160 same as it was with open cooling.
Click to expand...

the key being you stayed with the 160 degree thermostats no need for a new ECM
but you also arent getting the advantages of running at the more common gas engine 195. More fuel efficient, less carbon buildup, longer life etc
Running cold under load vs hotter will requires different timing advance curve, mixture curve, different knock sensor response (if equipped) The 160 ECM would likely consider 195 an over heating condition and back off.
Are these things really significant enough to justify the new ECM? probably not just stick with the 160 thermostat as you did
The immediate goal being corrosion protection not ultimate efficiency.
 
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