Heat Exchanger for Laser 28

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   Reclently Voila's original Bukh failed on the first day of our two-week sailing vacation.  We carried on without the engine and enjoyed our trip, choosing to get into the engine on return.  What happened?

A couple of months ago the engine became overheated caused by rust particles that broke loose from inside the head and cylinder cooling ports.  These particles lodged themselves into the little fitting at the exhaust elbow where the cooling water re-enters the exhaust and blocked the water system.  

When the engine cooled, and the blockage clear, the engine started and we ran it without incident for a couple of months, though these were mostly short runs to the start line and back.  On dis-assembly, it became evident that the head gasket had been compromised in the overheating incident and a small amount of water got into the combustion chamber, eventually causing the piston rings to get frozen in the down position in their grooves.  However, what was more interesting, was the amount of rust flakes I was able to remove from all the cooling ports and the vast amount of total metal loss on the inside of the head.  New heads come at about $2,000, plus everything else and all the work associated.  So I embarked on the idea of converting to a closed system using a heat exchanger and started planning the project.

Reading the Bukh Workshop manual available on the web, I see where Bukh says that this engine cannot be cooled by heat exchanger........I can't see why not.  If anyone has any information specific as to the "why not" of this, I would appreciate their comment.

My plan is to mount a pulley on top of the flywheel raised high enough above the main retention nut so as to safely clear the wheel, while driving a small pedestal mounted Orberdorfer centrifugal pump mounted from a new bracket fixed to the engine supporting bracket at the front of the engine.  The belt will run horizontally and the body of the pump will basically be upside down.  I plan to use the original Johnson pump to flow the raw water to the heat exchanger and exhaust, and use the new pump to drive the water/antifreeze mix through the original engine plumbing lines except making the two switches from the sea source to the heat exchanger, and the outlet switched from the exhaust to the expansion tank.

Can anyone see any flaw in this Thanks

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
frfletch Members Profile Send Private Message Find Members Posts Add to Buddy List Commodore Joined: 13 May 2008 Location: Canada Status: Offline Points: 365	Post Options Post Reply Quote frfletch Report Post Thanks(0) Quote Reply Topic: Heat Exchanger for Laser 28 Posted: 07 August 2010 at 1:18pm
	Reclently Voila's original Bukh failed on the first day of our two-week sailing vacation. We carried on without the engine and enjoyed our trip, choosing to get into the engine on return. What happened? A couple of months ago the engine became overheated caused by rust particles that broke loose from inside the head and cylinder cooling ports. These particles lodged themselves into the little fitting at the exhaust elbow where the cooling water re-enters the exhaust and blocked the water system. When the engine cooled, and the blockage clear, the engine started and we ran it without incident for a couple of months, though these were mostly short runs to the start line and back. On dis-assembly, it became evident that the head gasket had been compromised in the overheating incident and a small amount of water got into the combustion chamber, eventually causing the piston rings to get frozen in the down position in their grooves. However, what was more interesting, was the amount of rust flakes I was able to remove from all the cooling ports and the vast amount of total metal loss on the inside of the head. New heads come at about $2,000, plus everything else and all the work associated. So I embarked on the idea of converting to a closed system using a heat exchanger and started planning the project. Reading the Bukh Workshop manual available on the web, I see where Bukh says that this engine cannot be cooled by heat exchanger........I can't see why not. If anyone has any information specific as to the "why not" of this, I would appreciate their comment. My plan is to mount a pulley on top of the flywheel raised high enough above the main retention nut so as to safely clear the wheel, while driving a small pedestal mounted Orberdorfer centrifugal pump mounted from a new bracket fixed to the engine supporting bracket at the front of the engine. The belt will run horizontally and the body of the pump will basically be upside down. I plan to use the original Johnson pump to flow the raw water to the heat exchanger and exhaust, and use the new pump to drive the water/antifreeze mix through the original engine plumbing lines except making the two switches from the sea source to the heat exchanger, and the outlet switched from the exhaust to the expansion tank. Can anyone see any flaw in this Thanks