Yanmar 4JH4-TE Catastrophic failure

[Jlp0217]

I'm not any kind of expert, but looking at the pictures, it seams clear to me that the damage to the piston, and the bolt occurred on the downstroke, not the upstroke that bent the rod. I can't guess which happened first, but there is no stress on the bolt on the upstroke, and the piston has the bottom half destroyed, not the top half. I'd guess the piston seized, breaking the bolt just before the piston gave out, which happened before the second cap bolt broke. Maybe the rod was already bent, or maybe it bent on the next up stroke when it hit the seized piston.

[Wotname]

Originally Posted by Hunterdog

First, a huge thanks to all. I really am learning a lot about these engines. And I am at a distinct disadvantage from a language perspective as so much is lost in translation.
Update, the new engine was delayed a week in Barcelona...ahhhh Spain;

Here’s some more photos of the elbow, and the crank bolts

And about the exhaust: It’s located on the Starboard side, fairly high above the water line. We were on Starboard tack when this occurred.

This crack (circled) looks problematical to me. It might not have had anything to do with the engine failure but it should have been picked up in servicing IMO.

[OneBoatman]

To Hunterdog in Spain
You say your #4 cylinder rod "came off". Just what was the nature of the failure. Connecting rod journals than have 1200 "successful hours" do not just come off. So I would say you fell victim to a manufacturing defect most likely a crack that grew over time. Not being specifically familiar with a Yanmar conrod, most are castings that have a machined journal that is integral to the rod and another half round that may or may not also be a casting which secures it to the crankshaft. If I were t guess the failure was probably in the rod section. As a mechanical engineer with professional minor studies in metallurgy it is my experience that a crack that slowly progresses to failure is easily identified. The early growth of a material or process related defect that eventually progresses to a fatigue failure will generally appear rough and quite frankly aged in its appearance from oil and metal fines having penetrating and being trapped soon after its forming. The final growth leading to catastrophic failure tends to appear sharply broken as a clean break usually a change in path from the slower growth area and by comparison be obviously fresh when compared to the earlier. As an engineer I can say it is definitely not normal for an engine having had routine maintenance with working cooling and a normal oil level to fail under the conditions you describe. Can you say that the engine wasn't run in an overheated condition prior to your ownership?

[GGamble]

Have the same setup 2300 hours not a tick of a problem. 30,000 miles so far and it runs like a champ. 2013 Beneteau with dock and go, and I love it (but wish the bow thruster had more grunt). They have rev limiters. Plus 12 knots will not over rev a engine. All manufacturers experience random failures. There a new 112 foot yacht in Saunders Yacht Works getting a new engine. Last one failed randomly. It’s a large MAN diesel. And MAN makes great engines. Every one has failures. I had a Volvo Penta transmission fail at 60 hours on my 47.7. They all have failures. ZF and Yanmar both make great products. But.... there are failures.

[seabreez]

BIG BIG MISTAKE.
Bottom line...the #4 cylinder rod came off. Engine destroyed.
Comments please:[/QUOTE]

I WISH I COULD SEE THE PARTS. Did the rod break near the big end or the small end? Engine destroyed... why? Is the destruction caused by the rod that was whipping around and broke the side of the block? Can you post pictures? Roger

[Wotname]

Originally Posted by seabreez

BIG BIG MISTAKE.
Bottom line...the #4 cylinder rod came off. Engine destroyed.
Comments please:

I WISH I COULD SEE THE PARTS. Did the rod break near the big end or the small end? Engine destroyed... why? Is the destruction caused by the rod that was whipping around and broke the side of the block? Can you post pictures? Roger

Have you viewed posts # 19, 35, 70 and 121?

[PassportJoy]

I’ve seen it before... you hit something with your prop and it James, that caused your engine to instantly stop and the rod gave way... at least you have a new engine.

[skipperpete]

Originally Posted by OneBoatman

To Hunterdog in Spain

You say your #4 cylinder rod "came off". Just what was the nature of the failure. Connecting rod journals than have 1200 "successful hours" do not just come off. So I would say you fell victim to a manufacturing defect most likely a crack that grew over time. Not being specifically familiar with a Yanmar conrod, most are castings that have a machined journal that is integral to the rod and another half round that may or may not also be a casting which secures it to the crankshaft. If I were t guess the failure was probably in the rod section. As a mechanical engineer with professional minor studies in metallurgy it is my experience that a crack that slowly progresses to failure is easily identified. The early growth of a material or process related defect that eventually progresses to a fatigue failure will generally appear rough and quite frankly aged in its appearance from oil and metal fines having penetrating and being trapped soon after its forming. The final growth leading to catastrophic failure tends to appear sharply broken as a clean break usually a change in path from the slower growth area and by comparison be obviously fresh when compared to the earlier. As an engineer I can say it is definitely not normal for an engine having had routine maintenance with working cooling and a normal oil level to fail under the conditions you describe. Can you say that the engine wasn't run in an overheated condition prior to your ownership?

You might take a closer look at the pics earlier in the thread for a visual idea of what happened. The con rod is a forged steel component, not cast and appears to be only horrifically bent. The piston crown seems to have parted company after a fracture through the piston pin bore. In the pics there appears to be no sign of overheating but there are indications that raw water has been in contact with the crankshaft earlier in the engines life. The mixer elbow photo’s just posted could well be the root cause of the entire event, and certainly the cause of the turbo corrosion.
Pete.

[seabreez]

Originally Posted by Wotname

Have you viewed posts # 19, 35, 70 and 121?

Thanks for directing me to the pictures. After reviewing the pictures I came to the conclusion that the engine ran with a no load condition, or free wheeling not under load. When parts in an engine runs under load you can rev the be-jesus out of it and the same when de-accelerating. De accelerating the parts are under tension until low idle. When free wheeling the parts do not know where to go and spiral onto each different orbit and each part wants to go at different speed and go out of sink and fall apart. In parallel to that freewheeling condition, the connecting rod bolts had metal fatigue and broke off. In a freewheeling condition, usually the rod bends and breaks under the piston and whip around and break the lower end of the cylinder as in the pictures. in conclusion, you can have many different opinions on the causes and the fights you can have in determining or pin pointing the cause. Also this is very difficult to fight this in court. I wish I could bring better diagnosis... Roger

[Hunterdog]

Originally Posted by GGamble

Have the same setup 2300 hours not a tick of a problem. 30,000 miles so far and it runs like a champ. 2013 Beneteau with dock and go, and I love it (but wish the bow thruster had more grunt). They have rev limiters. Plus 12 knots will not over rev a engine. All manufacturers experience random failures. There a new 112 foot yacht in Saunders Yacht Works getting a new engine. Last one failed randomly. It’s a large MAN diesel. And MAN makes great engines. Every one has failures. I had a Volvo Penta transmission fail at 60 hours on my 47.7. They all have failures. ZF and Yanmar both make great products. But.... there are failures.

Well hopefully you’ll be luckier than me: I might have kept the dock and go, but it was not compatable with the new 80hp...and Yanmar would not sell me a 75 because they only offer them to commercial operations...worldwide...
So I had to switch to standard sail drive. (Pros and cons)
And I am 2 years into a 10 year circumnavigation...so I figured there’s less to go wrong with less electronics...

[kvstein]

I have a fairly new 3JH-5e. The owner's manual specifically forbids motor sailing and says the transmission must be in neutral while sailing. I turned on the motor once when the boat was fully powered by sail. Big noise and I have never done it since.

[Jim Cate]

Originally Posted by kvstein

I have a fairly new 3JH-5e. The owner's manual specifically forbids motor sailing and says the transmission must be in neutral while sailing. I turned on the motor once when the boat was fully powered by sail. Big noise and I have never done it since.

I wonder what that is all about? For me, that would be a deal breaker should I encounter a prospective boat with that engine and proviso.

Jim

[Wotname]

Originally Posted by skipperpete

....... The mixer elbow photo’s just posted could well be the root cause of the entire event, and certainly the cause of the turbo corrosion.
Pete.

Yes indeed!

Each new photo posted by the OP is another dot in the final picture and right now the dots are drawing a picture of an inadequately inspected / maintained engine - probably by the previous owner(s). If so, this should have been picked up during a engine survey at the time of sale. This is not so much a criticism, rather a timely reminder of the importance of a decent survey (and surveyor).

Rather than take a she will be right approach, it should be let's see what I can find wrong here.

[skipperpete]

Originally Posted by seabreez

Thanks for directing me to the pictures. After reviewing the pictures I came to the conclusion that the engine ran with a no load condition, or free wheeling not under load. When parts in an engine runs under load you can rev the be-jesus out of it and the same when de-accelerating. De accelerating the parts are under tension until low idle. When free wheeling the parts do not know where to go and spiral onto each different orbit and each part wants to go at different speed and go out of sink and fall apart. In parallel to that freewheeling condition, the connecting rod bolts had metal fatigue and broke off. In a freewheeling condition, usually the rod bends and breaks under the piston and whip around and break the lower end of the cylinder as in the pictures. in conclusion, you can have many different opinions on the causes and the fights you can have in determining or pin pointing the cause. Also this is very difficult to fight this in court. I wish I could bring better diagnosis... Roger

That’s a very entertaining diagnosis and if I understand it correctly it implies that an engine can only drive but will self destruct if it is driven . This will come as a surprise to tractor trailer drivers who use their engines to slow the rig on long steep downgrades, even occasionally running them up to hi idle in a moment of carelessness.
In the not too distant past we had 1,500kw standby generators that were driven on frequency by the mains power supply through the Alternator 24 hours a day for years, only coming under load at the monthly run and load test or if the facility lost Mains power.
Pete.

[RaymondR]

Originally Posted by Jim Cate

I wonder what that is all about? For me, that would be a deal breaker should I encounter a prospective boat with that engine and proviso.

Jim

Yep, that would be the end of my cruising, in the tropics about half the miles I make is motor sailing in light winds.