The number that several experienced mechanics have given me is that a well cared for (key words, there) marine diesel will get to the point it needs an over haul between 6 and 12 thousand hours. That's a HUGE range, and that is not too surprising since it is a very "fuzzy", yes even philosophical, kind of answer. An overhaul really is a performance based criteria, not something that has an expiration date.
Our 21 year old Volvo has 7,500 hours on it, and runs like a top. Putting out power at the same rate as it always has based on boat speed and rpm at full throttle. Based on the criteria above, it might run without a full overhaul for another 15 years... or it might need one in 5...
An injection pump is a VERY fussy piece of equipment. There is a reason that they have "tamper-proof" seals on so many of the adjustments. Overhauling one is a job for true specialists, not the average diesel mechanical shop. Clearances and settings are extremely small, and the test equipment needed to be sure it is running well is very expensive. On the positive side, they can run a very, very long time without a problem, and they are very rarely the cause of problems.
In general, if the engine is coming apart anyway, you can send the injection pump (and injectors) out for testing. If they test well, an overhaul is not needed.
---In amelyachtowners@..., <svperegrinus@...> wrote :
Hello Bill and Craig,
Yes, the question is about the fuel injection pump. On the Yanmar, it is a ZEXEL NP - VE - 4 / 12 F 1900 R NP1995.
Craig, interesting that you had the pump rebuilt at 4,000 hrs... we are not there yet, and at our current average, will reach 4,000 hrs in about 2 years. Just like you had the pump rebuilt at engine overhaul time, the Yanmar manual seems to implicate that the pump is to be overhauled at the same time as the engine itself...
... so along these lines... is 4,000 hrs perhaps the horizon for an engine overhaul on an Amel... ???
Yeah, kind of a philosophical question!
SM2K N. 350 (2002)