Yanmar 4JH4-TE Catastrophic failure

[Hunterdog]

Left Correllejo 3;30 am to make Morro jable, Canaria by mid day. Winds to be 18-25 kts. Swell 2m and decreases as we fall beneath the shadow of the fuertaventura. By 8, the sun just cracking thru the clouds, I handed the helm of the Beneteau Sense 50 to first mate Tracie, and my head hit the couch amidships. Winds 14 kts, 150 to 170 degrees off the starboard stern, and a following sea, we were making good time, averaging 6 kts. Autopilot requested some more battery, so 1400 rpm of the yanmar 4JH4-TE. I left it in gear as when I left the helm the speeds were down to 4 kts. A little extra speed would be nice to make anchor in day lite .
BIG BIG MISTAKE.
About 10 minutes later I hear a HORRIBLE winding noise as
the boat lunges forward...a rogue swell throwing us down a huge wave. We slid to 12 knots...
I shut er down, but it’s too late. After several sail-in anchorages, a few tows out, and finally ending up at Carzola, the Yanmar dealer in Gran Canaria. (I will write the riveting story of surviving the epoch Sahara sand storm of 2020, motorless, on 2 anchors later...see latitude 38, or follow us us on fb grateful sailor)
Bottom line...the #4 cylinder rod came off. Engine destroyed.
I just bought the new, improved 4J80 motor with a strait sail drive. No more electronics between me and the throttle. New motor has over speed protection built in.
After 100 years of motor-sailing...now?

I have 10,000 miles on this boat. Engine about 1200 hours. 2011 engine, with the dock and go system, which I have a love/hate relationship with. In oct 2018 left Turkey...

I feel that Beneteau, Yanmar, and ZF Marine produces an inferior product that would fail just running down a wave at 12 knots. Latent defect.
This is a massive safety issue...no?

Comments please:

[Wotname]

That does sound like a very unusual failure and very bad luck.

The engine would have been producing very little hp while motor sailing at 1400 rpm and the torque input from surfing(?) down a wave at 12 kts should not have broken anything in the drivetrain or the engine itself yet you threw a rod - strange.

If assuming the rpm was raised significantly by the torque induced by the increased boat speed, the governor would have reduced the fuel input to almost nothing.

To me it sounds like the #4 rod had a hidden defect and was ready to fail anyway. Perhaps the extra hull speed was simply the final straw breaking an already weak back.

[Hunterdog]

Good input. I have the broken parts. Maybe I should open an investigation?

[a64pilot]

For the same reason you can’t jump start a boat, the engine won’t be stressed if surfing.
The prop will just slip, there isn’t enough “traction” if you will for the water flow to drive the motor, or not by much anyway.
It just picked that moment break.

How many hours on the motor?

[Hunterdog]

1200 hours

[wsmurdoch]

In the wave face slide, did you heel enough, was the oil level low enough, to leave the oil pump suction dry and loose oil pressure and flow for a significant amount of time?

Bill

[Hunterdog]

Ya know, I have been talking to the yanmar dealer for days and arguing that it’s silly that such a failure should occur. He’s the shop in Barcelona....
Anyway, he’s convinced that over speed like this is a ‘thing’.
I can’t believe it either, cause with the thousands of boats out there, it would be happening ALOT.
So...must be a flaw in the engine??

I owned a 1993 hunter passage in California a few years ago, and crossing point conception at night in nasty swell and 25 knots...easily we could have had over speed....hmmmmm

[Hunterdog]

Oil was correct, no way were we sideways much, as it was a downwind run.

[jimbunyard]

I'm guessing it had something to do with back pressure/water ingestion/some mysterious hydrodynamic effect when the wave picked you up. Hard to believe that the failure was just a coincidence; had you been motoring at 1400 in flat seas, what are the chances?

[Hunterdog]

I save some of my ‘tracks’ on navionics. There is a ‘spike’ in speed almost on every passage when there’s wind and waves (they sorta go together). So this is really not unusual.

[Hunterdog]

Here’s a typical speed profile of a passage. Note the short spike up to 12.2 knots. This happens.
So, my engine should fail???

[Reefmagnet]

I'd be blaming some kind of hydrolock condition for smashing a conrod. I doubt any overspeed except hyper could do that kind of damage. If the conrod was defective, the crack face should reveal it although a quick check would be to note if it bent prior to failure.

[Wotname]

Originally Posted by Reefmagnet

I'd be blaming some kind of hydrolock condition for smashing a conrod. I doubt any overspeed except hyper could do that kind of damage. If the conrod was defective, the crack face should reveal it although a quick check would be to note if it bent prior to failure.

I think ReefM and Jimbunyard maybe on the money here.

Possible scenario - engine running at low rpm (1400), not much exhaust gas flow, cooling water pooling in the exhaust system and staying there until the exhaust back pressure builds up enough to push it out. Next lot of cooling water pools up but this time (at exactly the wrong moment), the stern picks up, boat starts surfing, gravity moves the pooled cooling water back towards the engine end of the exhaust. The wave possibly enters the far end of the exhaust and pushes the pooled cooling water far enough forward to hydrolock the aft most cylinder - game over!

Not saying this what happened but it seems feasible to me - a set of events that match the known facts. Of course there may be a another set of events that also explain the known outcome.

A close look at the conrod would be helpful. With a hydrolock I would expect the rod to bend before it broke. A latent defect in the rod should (IMO) show a developing crack face without any bend.

Hunterdog, was the broken rod nearest the flywheel? If so, in the Yanmar terminology, it is the #1 rod as the #4 rod is nearest the forward end of the motor (assuming no V drive).

[Jim Cate]

wottie, I find it hard to visualize sloshing forcing water back into a running engine, even at half speed or so.

I'd expect that in the event of the purported hydrolock there would be some bearing damage in the big end shell. Your insight about bending before breaking is spot on IMO... good thing to check on.

Over revving seems unlikely too, as these engines are governed, and I don't see the prop developing enough power to push it up to really high rpms, especially at only 12 kts or so (have we determined that it is a fixed prop?).

So, I kinda lean towards a latent defect but surely not convinced. A forensic look at the broken bits seems in order.

Back in my hot rod days I broke a few rods myself. Small block Chevy engines... we'd heat treat and then shot peen the stock rods. Made them a lot stiffer, but when they failed it was catastrophic. Had one that took out every moving part, all the valves, cracked the heads, tore up the block, broke the crank, oil pump, magneto drive gear... the only reusable bit was the injector fuel pump that was external to the timing cover and thus escaped the shrapnel. Came apart at well over 9000 rpm and put a temporary end to my racing.

Good luck to the OP... hope that you can get some compensation, somehow!

Jim

[Discovery 15797]

Originally Posted by Hunterdog

Good input. I have the broken parts. Maybe I should open an investigation?

If you're looking for wild a$$ speculation and sympathy, you've come to the right spot.

If you think that somehow you should be compensated, then you should talk to your insurance company and let them sort it out.

If you don't have insurance, you can contact an attorney. But, you'll likely pay a lawyer a lot of money and you are likely to lose unless you can find a metallurgist to analyze the failed part and testify it was faulty (which you will also pay for), and so you will likely be on the short end of any compensation if you do win your case. (Oh, and I hope you kept detailed engine maintenance records and the receipts!)

Good luck.