Additional Notice 4by2 owners

[knotflying]

My engine just quit today. Within minutes I had the problem solved thanks to a conversation I had with Fred Volkwein of the Alice J. He advised me back in June that his engine quit and it was the fuel pump relay that burned out. I purchased a spare and had one when needed. I purchased it at NAPA it is a bmw part made by tyco - 23134‑k59‑x313.
I am suspecting that the failure is related to vibration, but can't confirm that yet. The relay is located in the ECU box and is blue colored and 3rd one counting from left to right when you are looking at the box and facing starboard.

The clip that holds the relay assembly had partially failed and hence this relay was vibrating significantly more that the others. I have epoxied the clip back together and will be making provisions to help reduce vibration to these relays. For the life of me I cannot figure out why Yanmar decided to put such a sensitive component attached to a vibrating diesel engine. It has isolators between the ECU and mounting plate, but there is still considerable vibration. Keep in mind that this is the same plate that the fuel pump clamp is mounted to.

 

[BB marine]

It's interesting reading about this failure do to Vibration. The newer common rail engines with all the electronics takes the element of reliability of a diesel back a few steps. The old mechanical injector diesels were simple, limited electrical components, fuel solenoid, starter and alternator or some simpler then that generator/starter. Big displacement last for ever engines that had 2.5 to 1 ratio (Displacement to Hp). 250 CID Leman 80 hp. Whats better? I guess for our style boats I'll take the 1 to .62, 146 CID =220hp. Thats a lot HP from a small displacement engine and it is from the modern common rail design with all the electronics. With electronics 2 variables need to be watched Vibration and heat. I sounds like Vibration is the element of failure common to recent topics on Tugnuts. Same engine same model boat. For the most part the newer common rail diesels are light weight high speed engine and are balanced much better then there counter part (old style diesels). On newer engines there is a wider range that the manufacture can put that Critical speed. My question is what is that critical speed on the 4BY2. At what RPM does Yanmar feel is best to place there critical speed at? This may be a stretch and I may be over thinking this. What is the common rpm that R27 owners cruise at? How close to the critical speed of the engine is that. I would guess that the critical speed of a 4000 rpm marine engine would be somewhere in the mid point of the rpm range. I know this is a stretch but I have seen motor mount failures, alternator bracket failures, coupling failures due to boat owners running in the critical speed RPM. Mercruiser in the 80's and 90's placed it 1800 to 2000 RPM. The 4.3L Mercruiser vibrated so bad at critical that mercruiser installed cables to the motor mounts to restrict movement. I'm just having a cup of coffee thinking outside the box! 😀

 

[ALICE J]

Alice J is a 2011 RT 27 with a BY4 180 . The engine really shakes at idle rpm about 850. Smooths out about 950 or there about. I usually travel between 6 or 7 it’s. Engine had about 1300 hrs, When the failure happened four locks before Port Trent after doing the Trent Severn Canal twice, so perhaps idling was a factor. My socket was literally partially burned and melted, but usable for the NAPA replacement. I did replace two of of thr vibration damper bolts at 1100 hours prior to doing the Ontario canals. Have noticed the fuel pump bracket to be not broken. So Brian I travel at 1700 to 2200 rpm and only occasionally going 3950 WOT. Long talks with Mastery Diesel in St Petersburg, took them a while to tell me to look at the ECU after explaining the fuel pump not functioning. They then said said check the ECU.
So could other 4BY owners chime in with their engine hours? And operating rpm. Maybe we need to relocate the ECU?

 

[Salty7]

I too wonder why Yanmar engineers chose to mount the electronics and fuel pump directly onto a vibrating engine, it is mind boggling. My engine had a vibration fit right after I first bought the boat. I had run for about 1.5 hours and was in the middle of nowhere, I had to slow down to avoid some debris in the water and the engine started to run very rough. I took it out of gear and opened the engine compartment to see the engine shaking violently. The only thing I could find was the vacuum line that runs to the bottom of the turbo had come off. I think someone suggested it controls the waste gate. I pushed the hose back on and made sure the clamp was really clamping it in place. The engine settled right down and has been smooth ever since. If that really is a waste gate control hose it seems to do more than control a basic waste gate, maybe we have progressive waste gates and the boost curve is controlled by that little hose? There is quite a bit of boost on these engines and it comes on quite early at low rpm. I mention this as something to check because on my engine that detached hose really made a difference. That hose was not installed properly originally, the clamp was installed incorrectly, which is why it fell off. By the way, with the hose off it was running fine at speed, not so as I slowed back to idle. My hose is basic vacuum hose with a woven cover, with time and heat that hose is destined to deteriorate. My engine is 2012 4BY2-150, has about 125 hours now, I operate most of the time right below 80% load which is 3,350 to 3,450 rpm depending on conditions. There is 20 psi of boost on it at 3,400. As we reveal these findings to each other I think it a good idea to mention the year and model of the motor so we compare apples and apples.

 

[Boatdreamer]

We’ve had Gratitude for a little over 6 years now and we have about 450 hours on the 4BY2-180. I find if we’re not in a hurry 2300-2400 RPM is smooth and if we are 3150 is definitely the high speed sweet spot. If stuff keep breaking maybe a Corvette LS or BMW S55 swap is in order!

Tim
Gratitude R27
Yanmar 4BY2-180

 

[knotflying]

4by2 180 engine with 1467 hours. I usually run at 2,200 to 2,600 RPM and will run it up to 3,600 RPM occasionally.

 

[NorthernFocus]

It's interesting reading about this failure do to Vibration. The newer common rail engines with all the electronics takes the element of reliability of a diesel back a few steps. The old mechanical injector diesels were simple, limited electrical components... a lot HP from a small displacement engine and it is from the modern common rail design with all the electronics...

All of the electronics and a common rail fuel system aren't necessary to achieve the higher HP/disp ratio. The same can be done with direct injection, turbocharging, intercooling, and high operating speeds. The electronics and common rail design are necessary for EFI. Which in turn is needed to operate efficiently/cleanly across the entire RPM range. IOW the design is driven by air quality requirements. Which is the same reason that outboards went to four stroke. So we surrendered reliability for efficiency/clean exhaust.

 

[BaylorU]

“So we surrendered reliability for efficiency/clean exhaust.” Such a common theme these days....and long term, oftentimes a bad idea.

Just like using ethanol in our fuel...slightly cleaner emissions, combined with having to burn more fuel. But the farmers love it because they sell more corn.

Or requiring emissions crap (DPF, EGR, etc) on our diesel trucks...cleaner air (a great benefit), but at the expense of having to burn a ton more fuel per mile, and wearing out motors faster.

Always trade-offs, and unfortunately when politicians are involved the immediate benefit almost always outweighs the long-term consequences (because voters’ memories are about as short as a teenager’s attention span).

 

[Salty7]

I'm seeing lower RPMs than those I cruise at, which is fine if the boats are propped correctly and their engines can reach max rpm. Both the 150 and 180HP version of this engine are rated @ 4,000 rpm, they probably hit their governor at about 4,100-4,150 rpm. It is essential these engines (any modern diesel for that matter) be able to get to max rated rpm, 4,000 WOT in our case. These light duty diesels with turbochargers and aftercoolers don't like being overloaded. If the engine cannot reach max rpm it is overloaded constantly across the rpm range. We don't have EGT gauges but I would wager if we could measure exhaust temperatures we would find any engine that cannot reach 4,000+ rpm is running considerably hotter EGT due to the additional load placed on it. This causes premature wear and excess fuel burn because the engine is off the designed hp/torque/fuel burn curve at all engine speeds. I don't mean to lead us off track here but while we are sharing operating information felt those who don't know this need to know. It is very important not to run over-propped. By the way, the continuous rating for the 150 is 114 HP @ 3,600 rpm (90% of max rpm), that means Yanmar designed it to be run 24/7 at that rpm if you want to. I couldn't find the figure for the 180.

 

[BB marine]

injection, turbocharging, intercooling, and high operating speeds. The electronics and common rail design are necessary for EFI. Which in turn is needed to operate efficiently/cleanly across the entire RPM range. IOW the design is driven by air quality requirements. Which is the same reason that outboards went to four stroke. So we surrendered reliability for efficiency/clean exhaust.

Dan I agree with your post. The common rail design and electronics associated with this design are a component of emissions. The mechanical components do increase performance and efficiency but the electronic components do too. Its a win on both sides better for the environment clean burning increased efficiency which converts to increased performance. Down side is a reductions in the long term reliability.

To comment on the original post. I realize the subject of running for length at critical speed may be contributing to the vibration issues is a stretch but something to think about. The common failure posted are on similar boats, same power plant, running gear, reverse gear, hull, which are all components that can contribute to where that critical speed is. Based on the few post the rpm averages are most likely not in the area of critical speed because 2000 rpm to 2500 rpm is where the 4BY2 is starting to developing its greatest torque values. I would suspect that Yanmar would not put critical there and it would be below 2000rpm.

By the way, the continuous rating for the 150 is 114 HP @ 3,600 rpm (90% of max rpm), that means Yanmar designed it to be run 24/7 at that rpm if you want to. I couldn't find the figure for the 180.

180 hp Yanmar @ 3600 if correctly propped would be 135 hp which is close to 75% load this is where the Yanmar engine performs well at, with out reduction of reliability according to the manufacturer. I set my high cruise speed at 75% load and I base it on fuel consumption rather then RPM. For every 1GPH burned =18 hp is being generated. So for your 150hp at 3600rpm burning approx 6 GPH you are running at 75% power and 112.5 hp. I use GPH for load and HP calculations. Many of the dash gauges will display load values. The D3 does not so this is my way. 9 GPH is 165 hp and 75% load which is very close to 3600 rpm. I cruise at 3400rpm which is using 153 HP 8.5 GPH and 70% load this is where I like to cruise and the engine runs very smooth ( sweet spot).
This is side tracked from the post but you are correct, propping and improper loading of the engine can effect reliability.