Yanmar Diesel - Where are the Sacrificial Anode

[roverhi]

Questioned a Yanmar Distributor about the lack of zincs in my Yanmar 3GM30f's heat exchanger. They said the guts of the heat exchanger are cupro-nickel, other wise known as Monel, which is the most common material that is considered nearly corrosion proof. They say zincs aren't needed because of this. Other manufacturers use copper for the guts which is quickly eaten up by electrolysis if not religiously protected by zincs. Seems to work on my Yanmar as it's going on 20 years old. For corrosion issues, age is probably more of a causation factor than running hours.

[Zai]

Originally Posted by TacomaSailor

"Is it just plain corrosion getting these things, or electrolysis, would the zincs help?"

I spent a lot of time talking to the Yanmar dealer (parts and repair) and with the machinists about the question above.

Starting from the front of the engine:

- steel bolts
- bronze end cap holding the heat exchanger bundle into the housing
- nitrile (?) O-rings
- steel frame for heat exchanger bundle tubes
- copper tubes
- aluminum casting for housing
- steel bolts and studs holding heat exchanger/manifold to engine
- same end cap issue on back of engine
- steel gasket between heat exchanger and mixing elbow
- steel bolts holding heat exchanger and mixing elbow together
- silicon bronze mixing elbow

HOT saltwater making contact with bronze, copper, steel on the way thru the system.

what would the zincs protect with that mixture of metals?

I am trying to figure out if I should put zincs in my new heat exchanger

If you connected it to your batteries you could probably charge them

Aluminum and copper are two of the worst blends. I have thought about making titanium heat exchangers, it would be expensive, but the last one you would ever need.

[svfraidknot]

i have twin 79 model 4jh2e on my 78 solaris ,, as a rule i start my motors every week ,, my stbd motor is down to have the injectors and injector pump rebuilt .. port side still starts so fast you cant get off the key fast enoughh just bump the starter the stbd side was like that until i got some reallly bad fuel .. if i had the money i would just buy a new injector pump quoted 2300 plus tax , shipping etc. ,, after all this down time , parts taking 3 weeks paying 3 different mechanics i will have 1600 in the old pump ,,, i am selling my boat put an add here and have a lot on interest good boat best livaboard i have ever been on ,, what started this conversation i had 3 weeks off before i started the starboard side ,, again i just bumped her to start but i noticed rust in my exhaust first minute or two it ran ,, cleared up im wondering since that is the first time am i looking at possible problems or just 3 weeks not running this is usual ??

[Cheechako]

Originally Posted by a64pilot

?? what would you make a belt from? They are I believe Kevlar reinforced, just changed mine on my Miata the other day, Had I think about 100,000 miles on it, but the water pump was leaking and that is behind the timing belt so I put a new one on, still looked good, but think these things may look fine right up to failure.

Steel man, steel..... The key being your last sentence! I was just surprised they are still using them. Many manufacturers tried them a couple decades ago... but many went back.. Just another thing to pay someone to replace that wears out.

[a64pilot]

Timing belts have their place, their place in my opinion is high revving double overhead cam engine, not what you usually find on boats.

For a boat Diesel, I want a single cam in block engine, with push rods and rocker arms, I'd prefer the cam be gear driven, not chain