4JH2E injector pump leak - o-rings?

[Alii]

Suddenly have diesel leaking from the top of the fuel injector pump. I suspect it's the o-ring under the valve for cylinder #3 (and so the other 3 o-rings are suspect). The service manual on how to disassemble the pump has 15 other unrelated steps before removing the retainer and valve over the o-ring. It appears to me that I should be able to start right here, at step 16, and remove the stoppers and retainers to get at the o-rings. But before I blunder in ... perhaps someone out there has experience with these Yanmar FI pumps and can tell me if it's that easy?

Are these o-rings the thingies they're always warning us will be ruined by bio-fuels? Is there something better to replace them with than "original" Yanmar o-rings? If the o-rings in fact look OK, then the next suspect part to cause this leak would be ...???

[goodoldwoody]

I have a Bukh 32 (2 cylinder) and have had the same problem. The engine has done 1600 hrs. Fuel weeping out around one of the delivery valves. I replaced the o-rings on both. The one that was leaking stopped leaking but a few hours later the other one started leaking. Very annoying, difficult job to get at too. So I replaced the o-rings again doing both. It has not shown any sign of leaking for over a year now. Yesterday I could smell a hint of diesel. Had a look and there it was again.
I wonder if it is the fuel or is the engine running too hot. The engine is raw water cooled it runs pretty hot to touch but the water temperature gauge doesn't get above 35C.
A farmer friend of mine has had similar problems and he said to get "truck diesel" apparently a heavier grade and the problem with just go away.
This is Australia East Coast so I haven't heard of any changes to diesel like "Bio Diesel" is not available here.





Good

[Alii]

My o-rings had 17 years and 8700 hours on them -- time to replace, like pretty much everything else on the engine. There were definite hairline cracks in them. Replaced with what look like slightly beefier o-rings available at a Bosch Diesel Center which I think mainly services injector pumps from trucks hauling in and out of the container port. I still have the exhaust system dismantled so haven't been able to run the engine and confirm that the leak has stopped.

We spent 4 years on the Aus E Coast, then up thru Vanuatu, Solomons and PNG where most of the time diesel was ladled from 55-gal drums -- who knows what was in it. First ran into biodiesel labelled as such at fuel stations in the Phillipines.

[goodoldwoody]

Sorry I overlooked this in my reply: I too was also faced with the question of whether to attack the problem from directly above which seems the obvious and disregarded the other steps.
I think you are on the right track in sourcing the o-rings from the experts such as a Bosch or injector service centre as sometimes OEM parts such as these may not be quite up to scratch. Or even may not have been genuine OEM parts that were supplied since they failed so quickly. The previous engine was 28 years old with no leaks but worn out. Like your o-rings mine had cracks in them too. I will take the samples to my local injector service and see what they say. I am inclined to replace what appear to be the sealing washers located directly under the delivery valve body as they seem to me to be the parts that are doing the work of sealing and to me the o-rings are more of a secondary function. In my pump those very washers seem to be made from soft iron. Other pumps have what appear to be copper washers. My original though was that the sealing is done by the metal washer and the o-ring simply sealed the thread to prevent corrosion caused by seawater environment. We will see how we go.

Our cruising grounds are between Pt Davey Tasmania and Cairns.
But next we are hoping to cruise the Bass Strait Islands in summer and then head north for winter. There seems to be a restless "itch" to get away.

Thanks for your info.

[GordMay]

Greetings and welcome aboard the CF, goodoldwoody.