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Injectors & Valve Lash maintenance - how important?

Created On Thursday 12, August, 2010 6:40 PM by Vcoast

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Joined: Aug 2010

Note Thursday August 12, 2010 18:40 View thread in raw text format
Diesel Talk
I'm looking at buying a lobster boat with a 1998 Isuzu 6500 series turbo charged diesel 6Cyl engine. Makes between 165-185bhp. The engine has about 5200 hours. As looks go, still very clean for being on a lobster boat. The owner tells me the oil is changed every 100 hours, along with the filters, and have been meticulous about where they buy their fuel. While the boat itself is older, the general condition is good, and just looking around, there's no reason not to believe the owner regarding the regular oil and filter changes.

Here's the rub, in over 5000 hrs., no one has ever pop tested the injectors, or checked the valve adjustments. I've contacted the original company that marinized and mfg.'d the engine and they tell me the recommended maintenance for both is every 1000 hours. A local diesel shop recommends every 2000 hours as this is a rugged engine. The later tells me he recommends replacing all 6 injectors at this point, just due to the number of hours. The manufacturer tells me these engines can go 30,000 hours, however, that's only when the regular maintenance has been done along the way, which has not been the case here.

We took the boat out for a sea trial, and everything seems to run fine. There was only a little vibration at a very low idle, but a little kick to the throttle, maybe a 100 rpm ends it. No way to tell if that is inherent to the engine, or just a one of those goofy harmonic wave things that affects the whole boat. It's really minor, and hardly worth mentioning, then vibration at low idle a sign of anything? This is a dry stack exhaust, and keeled cooled engine system, so the exhaust stack exits above the cabin house and easy to see what's coming out, no black smoke, bad smells, or anything unusual through the whole power range.

So the question is, how concerned should I be about possible detrimental effects to the longevity if the valves and injectors have never been checked up to this point? Is it really possibly they could be perfect after 5000 hours? I've been told, poor injector spray patterns can cause hot spots in a cylinder. Regarding valve adjustment, I'm not sure how problems due to valve adjustment start to manifest, I suspect fuel economy, performance, pinging, nailing are all on the list, but these don't seem to be an issue.This engine sips fuel at 1 Gal. hour @ 2000 rpm, so, how out of whack could injectors or valves be without noticing it in performance, fuel consumption, audibly or visually along the way?

I took an oil sample and sent it off to a lab, and still awaiting the results. Any input would be greatly appreciated.

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Diesel Talk Forum

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Joined: Jan 2010

Note Saturday January 18, 2014 19:10 View thread in raw text format
Diesel Talk
I'm sure you have made a decision by now, but I would not let that bother me. Tough engines. Should go 30,000 as they say. Replace injectors, and do the 1000 hr maint. every 1000 hrs.

gregory l ralyea
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