Engine Maintenance

[bestfriend]

I am doing some work on my Universal M3-20 that was recommended by the engine surveyor when I bought the boat. It consists of replacing the raw water pump and the hoses that go with it. Also he writes, "The heat exchanger is showing some signs of corrosion. Clean up the end caps, service as necessary and replace the zinc anodes." The zinc is in the drain plug, so no problem there. The end cap that has the water-to-exhaust hose near it is corroded blue and there is salt build up at the nipple. That end looks like it needs work. So, my questions are,
1.- What do I need to do to "clean up the end caps"?
2.- Are there other things I should do while I have it apart?
And for the dumb question:
3.- Is the fresh water system going to drain when I open the heat exchanger?

I have lots of car engine experience, but am unfamiliar with the salt water parts on boat engines.

[BarryL]

Originally Posted by bestfriend

1.- What do I need to do to "clean up the end caps"?
2.- Are there other things I should do while I have it apart?
And for the dumb question:
3.- Is the fresh water system going to drain when I open the heat exchanger?

1. To clean the end caps, remove them (large bolt in the center) and use a wire brush, rag in solvent, or whatever you like to remove the scale, corrosion, etc. Depending on how bad they are you may want to paint them before re-installing.

2. With the end caps off, you may want to clean the heat exchanger as well. You can rinse water through it, push a rag through, whatever.

If you have time, check the condition of the gaskets, and order new ones if they are worn. If you don't have time buy replacements ahead of time.

3. The coolant (it should not be fresh water but standard automotive type coolant) will not drain because the raw water and coolant to not mix - it is a closed system. Seater will drain when you remove the zinc or end caps, but no coolant.

If you don't know when other maintenance was done you could also change the coolant, fuel filter(s), oil and filter, and transmission fluid.

For the coolant there is a drain on one side of the engine (same side as the throttle) that you connect a hose to so you can safely dispose of the old coolant). Open the bleed valve on the top of the engine and add new coolant.

I use a vacuum pump to change the engine oil and transmission fluid. Piece of cake and now you know are set for some time.

Good luck,
Barry

[bestfriend]

Thanks Barry. Say "hi" to all my old friends on Long Island for me.

[KeelHaulin]

In terms of the raw-water pump; you might be able to just replace the impeller if it is a type that has a front cover to pull out the impeller. Be sure you note the rotation direction and replace the new impeller with the correct blade "sweep" so the blades are not opposite of the rotation direction.

The other thing you might do is replace the fuel filter(s) and clean your fuel tank of both bio-growth and moisture. If there is access to the tank drain it out and wipe out the gunk to be sure it will not clog up your filters. I would also advise running 50% biodiesel because California has recently switched over to ULSD (Ultra Low Sulfur Diesel) which causes injection pump seals to shrink and leak. Biodiesel tends to have the opposite effect so mixing them should help combat/balance the negative effects of both. If you cannot clean out your tank then I would not switch over to biodiesel unless you have a dual (parallel) filter setup; biodiesel can cause filters to clog because the microbes get washed out of the tank much easier when running biodiesel. The only other issue with the new diesel fuels is the fuel lines; be sure they are in good condition, a USCG approved grade, and check them preiodically for any degradation (hardening or softening).

[Loewe]

I didn't see any mention of a heat exchanger to the water heater in your post. If your engine coolant runs to the water heater you really shouldn't use regular automotive coolant but "Low Tox". The reason is the lethality of even small amounts of anti-freeze in your fresh water system. Just something to consider. In addition, most radiator shops operating anywhere near the water, service heat exchangers in very much the same way they do radiators. I've had good luck with them in my area. Have fun!
Regards,
Red

[sailingdog]

Loewe-

Good point about the antifreeze and the calorifier.