On the way down to Fort Myers Beach in April the temp gauge went up to almost 200 degrees before dropping back down to 180. It had done this a few times the previous week. On the way back to Burnt Store Marina it did it again, but this time after the temp went back down to 180 it slowly crept up to about 195 and stayed there.
I started my investigation and confirmed that the raw water strainer was clean, water flow was good and the impeller was intact.
The next step was to check the thermostat. I tested it in a pan of water and it opened at 180 degrees.
Now it gets fun. While re-installing the thermostat, the cover plate broke when I tightened the bolts into the housing.
 |
| Old cover plate on the left |
 |
| Old cover plate on the left |
The old cover plate may have been original and was very brittle. Trans-Atlantic Diesel sent out a new cover plate for the thermostat. I also sent them the old one so they could use it to make new ones.
I re-installed the thermostat with the new cover plate and went out for a sea trial. The thermostat was opening but the engine was still running a little warm, about 190-195 degrees.
My next step was to run Rydlyme through the raw water side to clean it out. It had been about 500 hours since the last time.
While I was running the Rydlyme through the raw water side I noticed that the raw water was mixing with the coolant in the coolant tank. I finished with the Rydlyme and drained the raw and fresh water systems.
I filled up the fresh water side with water and pressured tested it. It would not hold pressure.
I pulled the heat exchanger off and could see that some of the tubes had split. This caused the raw and fresh water sides to mix.
 |
| Old heat exchanger tubes |
 |
| Old heat exchanger |
I decided to replace the heat exchanger instead trying to repair it, so it was back to Trans Atlantic Diesel for a new heat exchanger.
 |
| New heat exchanger |
 |
| New heat exchanger tubes |
While I was replacing the heat exchanger I also pulled the coolant tank off to be re-painted.
I then put it all back together and installed it onto the engine.
 |
| New heat exchanger and freshly painted coolant tank. |
 |
| Old heat exchanger and tank |
 |
| New heat exchanger with freshly painnted coolant tank |
So with everything back together I filled the coolant side and started up the motor. Everything was going well for the first ten minutes and then I started to hear a high pitched whine from the front of the motor. I shut down and poked around.
I discovered that the fresh water pump was very loose when I grabbed and shook it. It appeared that the bearings were not good and that this was causing the noise.
I pulled off the fresh water pump and it was obvious that it needed to be rebuilt. So you guessed it, back to Trans Atlantic Diesel for a rebuilt pump. I shipped it off and waited for it to return.
 |
| Old fresh water pump |
 |
| re-built pump |
 |
| Painted re-built pump |
 |
| Painted re-built pump |
 |
Re-built pump
|
 |
| The included gaskets. The one on the left was for the water pump. I soon found out what the one on the right was for. |
I got the pump returned quickly from Trans Atlantic diesel and re-installed it. Of course, being a forty year old engine something always goes wrong. There is a plate that installs onto the front of the motor and then the pump installs onto the plate. While installing the pump onto the plate, the plate cracked, just like the thermostat cover plate. The plate was old and brittle and cracked when the pump bolts were tightened.
 |
| The old broken plate is on the top. The new plate from Trans Atlantic Diesel is on the bottom. |
I again called Trans Atlantic diesel, I have them on speed dial now, and I was able to get the plate very quickly.
I installed the plate, now I knew what the other gasket was for, and the water pump. Everything went back together well and there were no leaks.
The fresh water side was now in good shape. I decided to do one last sweep of the raw water side. The strainer was clean and the impeller was intact. However, when I put the impeller cover plate back on, one of the old bolts broke.
 |
The broken bolt is on the right next to the post
|
I pulled the raw water pump off and did a very poor job of trying to drill out the broken bolt. So one last call to Trans Atlantic diesel, I hope, and I got a new Sherwood raw water pump. I will take the old one to a machine shop and see if I can salvage it for a spare.
The raw water pump arrived quickly and was installed without incident.
A sea trial showed that the thermostat was not opening at the right temperature. I diagnosed an air bubble and was able to get it out.
The second sea trial had the engine getting up to 180 degrees and staying there. We are now back to normal and back to cruising. We are keeping our fingers crossed that nothing else will go wrong for a while.
This whole episode took about three months. Most of the time was spent sending packages back and forth to Trans Atlantic Diesel. We also travelled to Oregon and Massachusetts for about three weeks.
I cannot say enough good things about Trans Atlantic diesel. If it were not for their expertise and availablility of parts this project would have been much worse and taken much longer.
