Yanmar Diesel - Where are the Sacrificial Anode

[Surfnski]

I have a Yanmar 4JH2-UTE, 1990 vintage. The engine is freshwater cooled. I have looked for sacrificial anodes in the salt heat exchanger but can not seem to find any. I have also poured through the manual and can not find a reference there either.

What am I missing? Does this engine not have zinc anodes in the saltwater circuit?

Thanks in advance.

Bill
s/v Alembic
Whitby 42

[Panope]

At some point, I believe Yanmar determined that the anodes were unnessesary and stopped using them.

My engine (late 90's, 3jh3e) does not have them either.

Steve

[Emmalina]

They have to sell spares you know

[Rhapsody-NS27]

I had found some Yanmar Parts Catalogs online some time ago, looking at the one for your engine, it doesn't look like it mentions zincs or anodes.

[delmarrey]

Nope! Yannys don't have them. This was brought up in a discussion a couple years ago. Maybe they figured they could sell alum manifolds a lot faster that way.

[TacomaSailor]

Originally Posted by delmarrey

Nope! Yannys don't have them. This was brought up in a discussion a couple years ago. Maybe they figured they could sell alum manifolds a lot faster that way.

I am in the process of replacing the heat exchanger and mixing elbow on my 1994 (2,900 hours) 4JH-2E because of corrosion damage.

I have taken the damaged parts to several machine shops to see about welding up the damaged areas. They all point out the lack of sacrificial material in the Yanmar when compared to most other marine diesels.

New exhaust manifold & heat exchanger with the cooling bundle and all necessary fittings is $2,195 and the mixing elbow is $850. That is 25% of the cost of a new 4JH non-turbo engine.

Search for my postings yesterday and today

[delmarrey]

At 80,000 miles I just spent $1200 on my Toyota Tacoma to get the timing belt changed w/water pump, tranny flushed and differential oil changed. Yanny parts are expensive but they did last you 2900 hours. Thats equivalent to 175,000 miles on a freeway, + or - depending on the RPMs.

[GordMay]

Greetings and welcome aboard the CF, Bill.

[a64pilot]

My Prius for whatever reason keeps up with and displays average speed, Even though we use it for a highway car the majority of the time, average speed is around 30 mph, making 2900 hours equal 87,000 miles.
Or 2010 Prius has 4,666 hours on it and isn't near it's half life I hope, automobile engines spend the majority of their life at low power output, it's boats and airplanes that are run hard, average life for a piston engine airplane motor is usually around 2,000 hours.

Only point is, it's hard to make comparisons between engines.

[a64pilot]

PO replaced the entire heat exchanger on my 87 4JHE, cost him $5,000. I've toyed with the idea of drilling and tapping in a couple of pencil zincs myself.
Is it just plain corrosion getting these things, or electrolysis, would the zincs help?

[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

[a64pilot]

Originally Posted by TacomaSailor

what would the zincs protect with that mixture of metals?

If I understand the issue, it's exactly the mix of metals that is problematic, in aircraft we call it dis-similar metals corrosion. I can't imagine how a sacrificial anode wouldn't help, but the anode would have to be bonded to the metal that is most susceptible to corrosion?

[Cheechako]

Originally Posted by delmarrey

At 80,000 miles I just spent $1200 on my Toyota Tacoma to get the timing belt changed w/water pump, tranny flushed and differential oil changed. Yanny parts are expensive but they did last you 2900 hours. Thats equivalent to 175,000 miles on a freeway, + or - depending on the RPMs.

WOW! Toyota is still using rubber timing belts? I thought the manufacturers gave up on those many years ago... But then.. my fave car maker Toyota has really been going down hill for years....

[RTB]

Originally Posted by delmarrey

Nope! Yannys don't have them. This was brought up in a discussion a couple years ago. Maybe they figured they could sell alum manifolds a lot faster that way.

Some do, some don't. My 3GMD has three, but this engine is raw water cooled.

I know they aren't cheap, but everyone should have a parts and service manual for their engine/transmission. Just sayin...
Ralph

[a64pilot]

Originally Posted by Cheechako

WOW! Toyota is still using rubber timing belts? I thought the manufacturers gave up on those many years ago... But then.. my fave car maker Toyota has really been going down hill for years....

?? 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.