Water Pump and Other Engine Work

This morning I decided to do some things with the engine that I had been reluctant to do lest I foul things up and wind up without the engine. But given that the engine is not woring anyway, I am at a safe anchorage, and Colin is hovering in the background, I figured that it was a good time to try these things.

I removed the sea water cooling pump and inspected the diaphragm. After the years of faithful service since I purchased the boat it was still in excellent condition. Nevertheless I swapped it out from my stock of spares that we had ordered from Norway during my stay in New Zealand. I telephoned Colin to see if he wanted me to leave the pump out so that he could inspect it. All that he was interested in was that the diaphragm was moving back and forth correctly. I bolted the diaphragm back on and saw good action when I turned the engine with the flywheel. I then bolted everything back on satisfied that in the future I can change the diaphragm while out at sea if required.

Colin gave me some interesting feedback during our conversation. He checked the book and the clearance between the top of the piston at TDC (top dead center) and the top of the cylinder must be in the range .040-.060 inches. I had measured .039" which was close enough.

The we discussed the engine cooling. The engine is supposed to run at an operating temperature of 120-150 F. I told him that at 1000-1100 rpm the temperature gauge barely moves off the peg. The highest temperature I had ever seem was 80 F at the end of a long run at 1600 rpm. I told him that both gauges (cockpit and nav station) reported the 80 F. He asked about the thermostat and I didn't have a clue (not surprising since I'm a still a kindergarten diesel mechanic running with training wheels). Colin had my books so he asked me to call him back in 10 minutes.

When I phoned back Colin told me that my engine has no thermostat. The book states that one should use the seacock to modulate the temperature by controlling the amount of water going into the cooling system. This seemed laughably crude to me and my initial reaction was to avoid tampering with the seacock. However, Colin told me that the tappet settings and piston ring clearances are set for a running in the temperature range 120-150F. I've been running engine cool - very cool. Colin said that when I run the engine at the proper temperature I'll get better compression, better fuel mileage, and burn less oil. So I after making sure that the seacock is stiff enough to not move when set I'll experiment until I get a good setting. As a double check on the temperature gauge readings I'll put my hand on the upper (water) part of the manifold which he says that it should be warm to the touch but not burning hot.

After this conversation I checked the transmission fluid level and brought it up to the specified level with about 200 ml of ATF (automatic transmission fluid). That transmission is definitely using a lot of ATF so I'll leave La Paz with plenty on hand.

Then I got adventurous and changed an engine anode for the first time. I'm glad I did because the one that had been installed in Port Townsend was almost totally eaten away. I think that there are two anodes but I could not find the second one. I'll look for a second one when I get my engine manuals back.

The top photo shows the diaphragm in place after the pump has been removed. The in-and-out action on that diaphragm is through the center bolt, which is driven from within the block.

The next photo shows the pump along side the diaprhragm which was OK but I chose to replace with the brand new one beside it.

The third photo shows the water pump back on the engine block after the job was completed.

The last photo shows the hard life of a sacrificial anode in a raw water cooling diesel engine.