I purchased a Moyer-rebuilt Atomic Four at the end of last season, about a year ago, and had it installed in my 1977 Catalina 30, replacing a thirty-year old original engine that finally gave up the ghost. Getting somewhat cocky with such a well-functioning engine, I decided to follow Don’s instructions on re-plumbing the raw-water cooled engine to provide hot water to the heater core in my hot water heater. Since I’ve owned the boat, the water heater has never been connected to the engine, so it has only functioned electrically, when plugged into shore power. This means that on cruises, we only get hot water for the first day or so, and then a series of cold showers (not always a bad thing on Chesapeake Bay in the summer!).
Shortly after completing the project, we embarked on a two-week cruise. I thought I would write up a report on the performance, for anyone considering the change, and pose some questions that have arisen. See Don’s FAQ No. 19, under Cooling System for details about the plumbing.
Prior to the modification, the engine ran at about 172 degrees under load, fully warmed up, just under 2000 rpms, with very little fluctuation up and down due to nominal thermostat operation. I interpret this to be just slightly above optimal 160 - 170 degree range, and completely acceptable.
The modification worked quite well. We had hot or warm water at all times during our trip.
As expected, the plumbing change makes the engine run hotter, due to the added resistance in the cooling water line. As Don instructs, I installed a ball valve in the bypass line, to restrict the bypass water a bit, so as to run more water through the engine block, and keep it cool. However, I found that I have to keep the ball valve virtually closed to get the engine back down to about 172 at 1700 - 1800 rpm, and it rises to 180 degrees at 2000 rpm, which is my hull-speed cruising power setting. The note in Don’s FAQ about not closing the ball valve too far, to avoid overcooling, is a non-issue.
In addition, I note that the amount of water exiting the stern of the boat is reduced significantly, and there is a notable amount of steam exiting the exhaust port in its place. I attribute this to the fact that, without the cooler bypass water being reintroduced into the manifold, much of the water is raised above the boiling point in the exhaust line, and exists as steam rather than liquid water.
At this point, my question then is: Since I’ve already blocked off my bypass, and the engine is still running somewhat above optimum temperature, am I better off just blocking off the bypass entirely and removing the thermostat, and letting all of the water pass through the block unimpeded? I’m aware that this might cause overcooling, as I ran an engine this way for a full season (at about 140 degrees) before I realized that there was no thermostat installed. If this is the case, I could re-install the ball valve in the cooling water line upstream or downstream from the block, to create some restriction and force the temperature back up to a proper level.
Assuming that overcooling can be controlled this way, are there any other problems that could occur with this configuration? Is the steam exiting the exhaust an indication that the bypass water needs to be restored? Perhaps if the overall system is cooled (if indeed it is), by removal of the thermostat, and warmed up to the minimum acceptable operating temperature by use of the ball valve, the steam condition may resolve itself.
I’d hate to have to go back to taking cold showers.
As always, I appreciate any thoughts by Don and others.
Jesse Delanoy
s/v Agapé
Baltimore
Shortly after completing the project, we embarked on a two-week cruise. I thought I would write up a report on the performance, for anyone considering the change, and pose some questions that have arisen. See Don’s FAQ No. 19, under Cooling System for details about the plumbing.
Prior to the modification, the engine ran at about 172 degrees under load, fully warmed up, just under 2000 rpms, with very little fluctuation up and down due to nominal thermostat operation. I interpret this to be just slightly above optimal 160 - 170 degree range, and completely acceptable.
The modification worked quite well. We had hot or warm water at all times during our trip.
As expected, the plumbing change makes the engine run hotter, due to the added resistance in the cooling water line. As Don instructs, I installed a ball valve in the bypass line, to restrict the bypass water a bit, so as to run more water through the engine block, and keep it cool. However, I found that I have to keep the ball valve virtually closed to get the engine back down to about 172 at 1700 - 1800 rpm, and it rises to 180 degrees at 2000 rpm, which is my hull-speed cruising power setting. The note in Don’s FAQ about not closing the ball valve too far, to avoid overcooling, is a non-issue.
In addition, I note that the amount of water exiting the stern of the boat is reduced significantly, and there is a notable amount of steam exiting the exhaust port in its place. I attribute this to the fact that, without the cooler bypass water being reintroduced into the manifold, much of the water is raised above the boiling point in the exhaust line, and exists as steam rather than liquid water.
At this point, my question then is: Since I’ve already blocked off my bypass, and the engine is still running somewhat above optimum temperature, am I better off just blocking off the bypass entirely and removing the thermostat, and letting all of the water pass through the block unimpeded? I’m aware that this might cause overcooling, as I ran an engine this way for a full season (at about 140 degrees) before I realized that there was no thermostat installed. If this is the case, I could re-install the ball valve in the cooling water line upstream or downstream from the block, to create some restriction and force the temperature back up to a proper level.
Assuming that overcooling can be controlled this way, are there any other problems that could occur with this configuration? Is the steam exiting the exhaust an indication that the bypass water needs to be restored? Perhaps if the overall system is cooled (if indeed it is), by removal of the thermostat, and warmed up to the minimum acceptable operating temperature by use of the ball valve, the steam condition may resolve itself.
I’d hate to have to go back to taking cold showers.
As always, I appreciate any thoughts by Don and others.
Jesse Delanoy
s/v Agapé
Baltimore
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