Yanmar Problems

[marina.alex]

I read a number of the threads ... we have a Beneteau 50 with the 4jh3-HTE and had similar problems ... it started when we equalized fuel tanks and then the engine would start running rough, losing RPMS .. the more load the worse it got.

We wasted 300l of fuel that we drained out and I gave away -- when we ran the diesel out of a 25 liter tank it ran fine, then started skipping and losing RPM. Eventually we pulled the fuel pickup out of the tank and I blew into it -- and it was very hard to blow into -- I then used a piece of spring steel to clean out the intake pipe -- kind of like a pipe cleaner. It was full of small shards of plastic from the tank.

The intake pipe from Beneteau is really small -- like 5mm wide ... it seems really small. When in Cyprus we had a guy tig-weld a 12mm pipe onto the fuel pickup and now all the gook gets sucked up and trapped in the Racor.

Fast forward a year we were on a passage from Sardinia to Sicily and noticed the engine skip occasionally. There were a few pieces of plastic in the Racor filter, but they also found their way into the plastic housing (the turbine mechanism) of the Racor FG500. So with some disassembly and cleaning I took maybe 1cc of debris out of the Racor and everything returned to normal.

Prior to finding this we had taken the exhaust elbow off, replaced all fuel lines, fuel filters, polished the tanks, took the fuel injectors in for service ... and then bypassed the fuel system ... and voila ... we found the problem -- a $20 solution at the welding shop. I wish I could get the $500of fuel back that I gave away. ... but we've put nearly 1000 hours on the motor since that time and we've been happy.

[Rakuflames]

Originally Posted by marina.alex

I read a number of the threads ... we have a Beneteau 50 with the 4jh3-HTE and had similar problems ... it started when we equalized fuel tanks and then the engine would start running rough, losing RPMS .. the more load the worse it got.

We wasted 300l of fuel that we drained out and I gave away -- when we ran the diesel out of a 25 liter tank it ran fine, then started skipping and losing RPM. Eventually we pulled the fuel pickup out of the tank and I blew into it -- and it was very hard to blow into -- I then used a piece of spring steel to clean out the intake pipe -- kind of like a pipe cleaner. It was full of small shards of plastic from the tank.

The intake pipe from Beneteau is really small -- like 5mm wide ... it seems really small. When in Cyprus we had a guy tig-weld a 12mm pipe onto the fuel pickup and now all the gook gets sucked up and trapped in the Racor.

Fast forward a year we were on a passage from Sardinia to Sicily and noticed the engine skip occasionally. There were a few pieces of plastic in the Racor filter, but they also found their way into the plastic housing (the turbine mechanism) of the Racor FG500. So with some disassembly and cleaning I took maybe 1cc of debris out of the Racor and everything returned to normal.

Prior to finding this we had taken the exhaust elbow off, replaced all fuel lines, fuel filters, polished the tanks, took the fuel injectors in for service ... and then bypassed the fuel system ... and voila ... we found the problem -- a $20 solution at the welding shop. I wish I could get the $500of fuel back that I gave away. ... but we've put nearly 1000 hours on the motor since that time and we've been happy.

The pickup on my tank is very small, too. But if you think about it, a diesel engine needs a very small spray of diesel to fire off, and even a tube to take the unused fuel back to the tank. Diesel engines are super-sensitive to dirt, and I went through all you described -- with a brand new engine, mind you -- because the tank was dirty.

[luso]

Have you check back pressure in the exhaust?Depends where the exhaust exit the boat,when healing or baucing the pressure inside the exhaust increase. .

[Sailor_Russell]

I have a 4JH-HTE in a Hans Christian 38. I purchased this boat January 2015 and the engine wasn't running. Turns out the plungers were frozen in the IP. I've got the engine running now, except with one problem. The #1 cylinder isn't firing. When I crack the injectors to bleed the air the fuel coming from the injector pump going to number one sprays a fine mist. All the other cylinders are firing strong. I purchased new plungers and replaced all four. Reinstalled the injector pump and nothing changed, #1 from the IP is still spraying a fine mist. Any ideas?

[delmarrey]

It sounds like it's time for a compression check.

[Sailor_Russell]

Hi Del, thanks for the reply. I probably didn't write the symptom out very well. When the injector pump delivers the fuel it should send out a solid gush with every stroke, not a fine mist. This is the injector pump I'm having the problem with, not the injectors. I changed out the plungers and all are delivering fuel properly, except for the #1. I was curious if anyone has had a similar problem? And when I say I fine mist, it literally looks like when you spray a perfume bottle coming out of the injector pump line.

[DeepFrz]

What does it look like at the pump if you disconnect the line. Sounds like there might be partial blockage in the line??

[donradcliffe]

I've read this thread before with interest, but read it again today because Dockhead's symptoms are identical to what I have just experienced.

I just delivered the race boat Merlin from Hawaii to Santa Cruz, getting in yesterday afternoon after 12 days. The weather went abnormal the last 300 miles, resulting in 40 hours of motoring on a Yanmar 4JH3-TE. I kept the rpms at 2500 for about 28 hours, then the motor lost some power and would only do 2300. Temperature gauge was just at the beginning of the red, but It had been running there on two previous deliveries this year, and extensive checking with an infrared thermometer showed normal temps--the highest temp I could find was 175 degrees at the thermostat housing/gauge area. No smoke, running smooth, vacuum on fuel gauge reads zero.

The engine will run smoothly down to idle, and under load it is responsive to throttle advances up to 2300 rpm, then just won't go any higher. Revving it up in neutral, it limits out at about 2900-3000--pretty much the same as Dockhouse's problems. Engine has about 1300 hours on it.

The boat was stripped for the Transpac, so my spares and tools were limited and I limped home at 2300 rpm. Now I need to figure out what the problem is and how to solve it.

Based on this thread, there has been no real smoking gun found. Possible causes could be sticking turbo, fuel problems, or injection pump. To me, the no load limit makes the injection pump the first place to look. I hear Dockhouse's problems stopped when he gave the IP some love, but reoccurred later. However, my father always taught me to work on the cheapest solution first, so I may start with the turbo.

Because of the extended run with low boost, I was planning to end my trip with a half hour at 28-2900 rpm, but didn't get the chance. First I'll try to see if there is any boost. If not, I'll try a couple of washes, and if no joy then take the turbo off and make sure it runs free.

Any comments and suggestions would be welcome.

[Dockhead]

Originally Posted by donradcliffe

I've read this thread before with interest, but read it again today because Dockhead's symptoms are identical to what I have just experienced.

I just delivered the race boat Merlin from Hawaii to Santa Cruz, getting in yesterday afternoon after 12 days. The weather went abnormal the last 300 miles, resulting in 40 hours of motoring on a Yanmar 4JH3-TE. I kept the rpms at 2500 for about 28 hours, then the motor lost some power and would only do 2300. Temperature gauge was just at the beginning of the red, but It had been running there on two previous deliveries this year, and extensive checking with an infrared thermometer showed normal temps--the highest temp I could find was 175 degrees at the thermostat housing/gauge area. No smoke, running smooth, vacuum on fuel gauge reads zero.

The engine will run smoothly down to idle, and under load it is responsive to throttle advances up to 2300 rpm, then just won't go any higher. Revving it up in neutral, it limits out at about 2900-3000--pretty much the same as Dockhouse's problems. Engine has about 1300 hours on it.

The boat was stripped for the Transpac, so my spares and tools were limited and I limped home at 2300 rpm. Now I need to figure out what the problem is and how to solve it.

Based on this thread, there has been no real smoking gun found. Possible causes could be sticking turbo, fuel problems, or injection pump. To me, the no load limit makes the injection pump the first place to look. I hear Dockhouse's problems stopped when he gave the IP some love, but reoccurred later. However, my father always taught me to work on the cheapest solution first, so I may start with the turbo.

Because of the extended run with low boost, I was planning to end my trip with a half hour at 28-2900 rpm, but didn't get the chance. First I'll try to see if there is any boost. If not, I'll try a couple of washes, and if no joy then take the turbo off and make sure it runs free.

Any comments and suggestions would be welcome.

My problem was solved by changing the fine filter on the engine.

Engine has been running perfectly for a couple thousand hours since this thread was posted.

I tried to install in-line fuel flow meter transducers and the problem recurred. I had to take them out again.

It seems that these engines are extremely sensitive to very small flow restrictions in the fuel system.

[donradcliffe]

Thanks, Dockhead. I have ordered the platinum plated fuel filter from Yanmar and will see if it solves the problem. I did run the engine today--the turbo is spinning nicely at idle , but the top rpm in neutral has dropped to 2500, so it looks like the fuel starvation problem is gradually getting worse.

[steve77]

I have the same engine, had the same symptoms, and fixed it the same way. Replacing the "platinum plated" (I love that description!) engine-mounted filter solved the issue.

While digging through my spares I even found THREE more of those filters that I had forgotten about. A veritable fortune.

On a related issue, my Yanmar manual says "When operating the engine at low speed for long periods of time, race the engine once every two hours". The manual is vague on what is considered "low speeds", so I don't know if 2500 rpm on an engine rated for 3800 rpm is considered low speed or not.

I mention this because I now cruise at 2500 rpm and I do the engine racing as instructed. Before, I used to never run the engine above 2500 rpm, and the only way I noticed that the engine would not reach high rpms was if I needed sudden power during docking and it wasn't there. Now, I know much earlier if I have a fuel restriction problem.

Cheers!

Steve

[marina.alex]

After another 1000 hours of smooth powering I'd recommend putting a bigger fuel tank pickup in like we did, then change the racor and the expensive fuel filter that's mounted on the front side of the engine. I also replace my fuel lines every couple of years .. our boat lives mainly in Greece and it's really hot here, plus we're on the Tarmac for 10 months a year so the rubber can get brittle. I reckon a little air intrusion from a hairline crack in a fuel line would prevent full performance.

It is funny that this happens because I'd guess that more fuel gets poured back into the tank from the return line than is used by the engine ... but we had a lot of mechanic time and expense and in the end it was a silly $25 fix that did the trick -- and the repair has worked for about 2000 hours.

In my experience, if turbos are getting air and oil they're pretty reliable. I wash out my air cleaner about every 100 hours or so. It's two clips and a metal screen covered with plastic. The only pain is disconnecting the rebreather hose if you have normal sized hands. The turbo can be accessed by taking off the exhaust elbow to check for play or too much carbon.

We've adopted the 'slow cruise' approach of 1500-2000 rpm to be quiet but will run hard at 2800 for an hour every once in a while. Especially if we seem to see a little more smoke than usual.

Also I bought a stainless steel exhaust elbow from a guy that makes them and sells them direct on eBay that was really cheap -- like $300 so I replaced my aluminum one with a stainless one and kept the old one as a spare. My experience with boat engine problems is work back to front ... exhaust clean and unrestricted? If yes then go to the input side. High temp could be a restriction in exhaust flow ... corroded exhaust elbow ... this has cost me an engine on my little powerboat .. symptoms were lower performance, higher temps. Then check the fuel side ... we did that bypassing the fuel tanks with a five gallon jug and that solved our problem ... so we tested each fuel component ... finally figured it was the fuel tank pickup ... and the culprit was a new webasto heater installed that the installer tapped into the fuel tank and the shards of plastic from the hole saw fell into the tank and got sucked into the small pickup tube ....


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[hpeer]

MarinaAlex,

Could you please share your source for the SS exhaust elbow. I need a custom one made up by stretching (making taller) a standard elbow. But Yanmar wanted something like $650 for a standard elbow, which I then have to modify.

[hpeer]

I'm pretty sure I posted this before but here goes....

Similar problem after picking up some gunk on a rough passage. The Platnium filter was really junked up.

Symptoms were engine would only rev to 1600 FWD, REV, or NEUTRAL.

Removed IP an had it serviced. Service center reported NO problems, just dirty.

Be careful when removing the IP to not loose your orientation between the gears, this engine uses an idler gear and if you are unaware it can be a real pain to re-establish timing.

[DeepFrz]

donradcliffe, if your vacuum gauge reads zero I would check to make sure that your primary filter isn't leaking fuel past the filter. If your filter is doing something the vacuum gauge should read higher than zero but less than 10 or 15 (your choice).