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Old 23-03-2021, 13:11   #1
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Yanmar 4JH45 minor diesel leak from fuel pump

Hi All,

We have a 2.5 year old Jeanneau 419 with a Yanmar 4JH45. The engine has about 260 hours on it, and has had all the required and regular maintenance done by a professional.

Recently (about 20 engine hours ago), I have noticed that after running the engine for about 2 hours, there is a small amount of diesel that appears between the fuel pump and the engine.

The leak only appears after about 2 hours of continuous engine running, and is never enough to even drip into the bilge - its just wet to the touch and usually dries off once the engine is shutoff.

I have had a yanmar dealer look at the unit, and they think it might be a small leak in the shaft seal between the engine and the pump, apparently the only option would be to repace the entire unit (approx $2000), because they dont have the expertise to just fix the seal.

Their recommendation is because its a very minor leak to just monitor it and not be concerned unless it gets worse.

Wondering if anyone has any similar issues with these engines - we are not planning big offshore sailing soon, so happy just to monitor it, but curious if anyone has had similar issues.


On a side note, I was under the impression that our enigne had a 2+3 year warrantee, but now yanmar say that the +3 year only covers major components. Our waranty handbook talks about 2 separate warranties, a 3 year on major components, and also a 3 year extension to the 2 year normal warranty - Yanmar claim this is incorrect, but curious if anyone has come across this?

Trying to attach pic of the leak, but looks like I cant

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Old 24-03-2021, 11:04   #2
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

Disclaimer: I don't know how to replace an oil seal on a Yanmar fuel pump.

Do you want to tackle it?

That said and if so, I've never met an oil seal that was particularly difficult to replace. They are usually held in place with interior or exterior spring clips, and they are available in all shapes and sizes. Yanmar didn't design its own; they are stock items:

https://www.mcmaster.com/oil-seals

Do you have an exploded parts view of the fuel pump? That's usually the best place to start if you want to tackle something mechanical. The process then is methodical disassembly, laying out parts in the order they came off, and taking photos if you are concerned about whether you will get it back together again. Replace the worn seal, making sure there is no grit involved, and methodically put it all back together. Immediately after completion of the assembly, stir together one measure of London gin, four measures of tonic water, a handful of ice, and a squirt of lime juice. Do you need instructions on how to utilize that?
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Old 28-03-2021, 08:44   #3
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

Welcome to the forum Gennetay,
I would have thought an injection pump qualifies as a major component but thats just me, not the fine print.
Amazing Yanmar service dept that cant fix a leaking injector pump or at least send it out to be fixed. Hard to believe it needs replacing, they are rather expensive too. Eg 3gm30 yanmar injection pump is about US $1200 in the US. & about $2400 NZ$ here

Dont know yr engine but I imagine a diesel injection shop can fix it for you if you aren't happy to try it yourself. I wouldnt touch it unless you are mechanically skilled but tkeithlu has given you good advice except I'd substitute whisky for gin
Yanmar should be doing it free of charge at that low hours IMO
Hard to believe it wont get worse if its starting leaking that early in the engines life but I'm guessing there.
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Old 28-03-2021, 09:14   #4
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

On engines I'm familiar with, the seal on the shaft driving the injection pump is there to prevent fuel from entering the crankcase. I'm not familiar with your engine but have to wonder if it is occurring? How does your crankcase oil level look? I discovered my injection pump's shaft seal had failed when I noticed my oil level had increased!

I cannot comprehend how a fuel injection pump on a diesel engine is not a major component, unless warranty defines 'major' to exclude all external parts, i.e, starter, alternator, freshwater pump, etc.
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Old 28-03-2021, 13:31   #5
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

Beware, this is not the old mechanical injection system we know and love, this is Bosch common rail operating at 2,000 BAR!!! Open this thing up at risk of personal harm or pump damage.
Pete.
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Old 28-03-2021, 14:44   #6
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

Welcome aboard CF, gennetay.

I have yet to see a 'minor' leak (oil or fuel) on a as new engine not get worse. Said in a better way, - such leaks always get worse. Your engine is as new as it can be and it shouldn't be leaking, 2,000 BAR not withstanding.

Of course the injection pump is a major item, it is the heart of a common rail engine except perhaps in the minds of the Yanmar legal team...

Hope you get it resolved painlessly.
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Old 28-03-2021, 23:07   #7
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

Quote:
Originally Posted by skipperpete View Post
Beware, this is not the old mechanical injection system we know and love, this is Bosch common rail operating at 2,000 BAR!!! Open this thing up at risk of personal harm or pump damage.
Pete.

VERY GOOD POINT!
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Old 29-03-2021, 04:52   #8
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

Quote:
Originally Posted by tkeithlu View Post
Disclaimer: I don't know how to replace an oil seal on a Yanmar fuel pump.

Do you want to tackle it?

That said and if so, I've never met an oil seal that was particularly difficult to replace. They are usually held in place with interior or exterior spring clips, and they are available in all shapes and sizes. Yanmar didn't design its own; they are stock items:

https://www.mcmaster.com/oil-seals

Do you have an exploded parts view of the fuel pump? That's usually the best place to start if you want to tackle something mechanical. The process then is methodical disassembly, laying out parts in the order they came off, and taking photos if you are concerned about whether you will get it back together again. Replace the worn seal, making sure there is no grit involved, and methodically put it all back together. Immediately after completion of the assembly, stir together one measure of London gin, four measures of tonic water, a handful of ice, and a squirt of lime juice. Do you need instructions on how to utilize that?
Keith,

I was carefully reading and mentally taking notes until I got to the methodical G&T instructions.

(Boy, did I get sucked in!)

Laugh's on me,
Good one,
LittleWing77

(Although my fav is Bombay Sapphire...)
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Old 29-03-2021, 05:16   #9
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

This is my problem with Yanmar (formerly my favourite engine) in general and common rail technology in particular.

So the added component that Yanmar doesn't tell you is that their warranties (especially on their common rail engines) are maintained ONLY if you have "Yanmar Certified Technicians" conduct the engine work, only using Yanmar parts.

Since (as Keith says above), they don't make a Yanmar seal for that pump, suddenly what we've all conceded is a major engine component gets magically transferred to something "non-essential", not covered by their warranty...

As a Marine Services employee, I dealt with this Yanmar labyrinth with a Club Member's Hanse 50 and brand new common rail Yanmar with an overheating problem. Aggrivating in the extreme.

Good luck - and if you want to maintain your warranty, for those first 3 years, ensure that only a Yanmar-Certified Tech does your engine work.

Sorry to be such a downer, Gennetay,
Oh! And Wottie has spoken and Wottie is King
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Quote:
Originally Posted by Wotname
Welcome aboard CF, gennetay.

I have yet to see a 'minor' leak (oil or fuel) on a as new engine not get worse. Said in a better way, - such leaks always get worse. Your engine is as new as it can be and it shouldn't be leaking, 2,000 BAR not withstanding.

Of course the injection pump is a major item, it is the heart of a common rail engine except perhaps in the minds of the Yanmar legal team...

Hope you get it resolved painlessly.
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Old 29-03-2021, 17:08   #10
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Re: Yanmar 4JH45 minor diesel leak from fuel pump

2000 bar? That’s around 29,000 psi!
I thought it was a typo, and should read 200 bar.
https://en.wikipedia.org/wiki/Common_rail

I don’t think I would tackle my own seal change on a nearly brand new fuel system that runs at 29,000 psi.

And Yanmar is nuts if they don’t cover this under warranty.
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