Manufacturing defect or design flaw

[Tim R.]

Some of you have been following my engine coolant issues in this thread:

http://forums.sbo.sailboatowners.com/showthread.php?t=133796

I received the new HE/exhaust manifold today. After seeing the new part, I will definitely contact Yanmar tomorrow for an explanation.

 

[Maine Sail]

Clearly they've made changes for the better. I would call it a design flaw..

 

[CarlN]

As Gomer Pyle would have said:

Surprise, Surprise, Surprise!

 

[tommays]

If I am understanding the design the exaust gases were cooled in the thin lower section by antifreeze ?

Not much room there for any wear at all BUT I Guess it's better than all the aluminum ones that failed on other motors

 

[Ross]

Some very signifigant changes have been made. I would suspect an aluminum exhaust manifold in the best circumstance. loose cooling for just a couple of minutes and you could melt that.

 

[tommays]

http://www.yachtsurvey.com/diesel_engines.htm

Heat exchangers seem to be a big area for failure

 

[Ross]

There was a time when the engine cooling was accomplished with a couple of tubes running along side the keel. The water cooled manifold was independent of the engine cooling. One water pump for the exhaust and one for the cooling system of the engine.

 

[Cayennita]

How often did you check the zinc plug on the old heat exchanger. The photo appears to show damaged because of no zinc. Sorry, I have not followed the forum.

 

[petersea]

Design change does not necessarily equate to design flaw. The salt water environment is tuff on all parts (especialy metals)and they have a "life". Equipment does not last forever. Engine mfg are constantly updating parts and parts numbers . Design flaw if engine is new or only several years old but twenty year old part is just just worn out. The original part is 14 years according to your original posting maybe it is just worn out. Maybe the original part was not the best design but 14 years of use at an average of 142 hours per year of use is not a design flaw.

 

[Tim R.]

The failure happened on the fresh water side and the entire inside of this part looked like new except for where the pinhole was. The new part has significantly more material only in the area of the failure. No zinc on this model. I will be adding one.

 

[thinwater]

There was a time when the engine cooling was accomplished with a couple of tubes running along side the keel. The water cooled manifold was independent of the engine cooling. One water pump for the exhaust and one for the cooling system of the engine.

Still alive and well on the skipjack push boats (yawl boats) of Deal Island!

Yes, very simple.

 

[kloudie1]

I agree.. new one looks lots better. The cores of the mold have been modified which would make them more stable during the metal pouring... making for a more controlable wall thickness of the jacket. Tim it almost looks like a very little bit of seawater may be getting back to the flange connection? or am I seeing the results of the coolant weeping over time which would have made a corrosive ?? Chicken/egg thing.. Looks like a fine new casting.

 

[Tim R.]

Tim it almost looks like a very little bit of seawater may be getting back to the flange connection? or am I seeing the results of the coolant weeping over time which would have made a corrosive ?? Chicken/egg thing.. Looks like a fine new casting.

Claude, the dark spots on the old flange are staining from the metal gasket. The mating surface is otherwise in very good condition. The only moisture that should get in there would be a direct result of combustion.

 

[kloudie1]

OK..Sounds good, Tim.. I was looking at the 6 o-clock where the ID looks ragged and corroded.. even to the point of almost releasing the stud at the 7 o=clock..again, the core slipping during a pour can do that.. and the foundary must have made a few like that to have recognized the problem and corrected it.. No question that ya have a much better one now..

 

[Tim R.]

Yanmar has denied any problem with that part. Their explanation for the change was to handle engines with more HP although these engines(4JH3E) only have a very slight increase over the 4JH2E. Their other explanation is that it may have been retooled because the original tooling wore out.

I was not able to send the picture on the original submission but have since sent it to them to see what they think.

 

[kloudie1]

OK, I can believe tooling worn out = castings not uniform.. Never hurts to talk to those guys..
Just curious..Is the exhaust passage hole in the mating flange the same size as the passage in the new manifold or the old one..??

 

[Tim R.]

OK, I can believe tooling worn out = castings not uniform.. Never hurts to talk to those guys..
Just curious..Is the exhaust passage hole in the mating flange the same size as the passage in the new manifold or the old one..??

I do not recall although I know the new gasket matches the new manifold.

 

[Benny17441]

We broke the tack ring on the Furlex 100 that came with the h320. A replacement part was shipped free of charge by Furlex and you could tell that the tack ring had been redesigned and was now much beefier. There was no mention about the riggin costs for installing the new furler head. The original part was rated by Furlex for boats up to 30 ft but they were willing to sell and Hunter was willing to install them in a 32 footer. At first I was surprised they were so accomodating in replacing the furler head for free then it became obvious.

 

[Gunni]

Yanmar 4JH3E - no zincs!

I've got that engine, and when I went looking for the zincs, was surprised to find none. When I asked why Yanmar where the zincs were located, they told me that the raw and fresh sides are isolated by a non-conductive gaskets - hence no galvanic. You mention a "metal gasket", is it possible that this is not OEM, or was not properly aligned and became a conductor for the galvanic process?

 

[Tim R.]

I've got that engine, and when I went looking for the zincs, was surprised to find none. When I asked why Yanmar where the zincs were located, they told me that the raw and fresh sides are isolated by a non-conductive gaskets - hence no galvanic. You mention a "metal gasket", is it possible that this is not OEM, or was not properly aligned and became a conductor for the galvanic process?

There are o-rings that isolate the fresh water side from the raw water side. There are absolutely no signs of corrosion on either side of the heat exchanger. I believe the problem was caused by heating/cooling cycles and the ridiculously thin water jacket around the exhaust.