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Old 11-19-2010, 07:06 AM   #41
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48
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RE: Replacing a Ford Lehman SP135

Underloading problems with a 4 stroke diesel is a myth that will not die.* If concerned, run 80 - 85% off top end rated RPMS for 15 minutes during your daily runs (not at idle either). So long as your water and oil temps get to spec at your selected cruise RPM, you are fine. Oil temp must be above 175 with 185*- 200 a normal no problem*range.

More important than underloading imho is low use and letting sit over winter when not properly prepped. I see on boat diesel that an owner with a 14 year old engine averaging 35 hours per year suggests a class action suit against CAT because of antifreeze in oil --- and rotted out cooling system.

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Old 11-20-2010, 04:52 AM   #42
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RE: Replacing a Ford Lehman SP135

"Underloading problems with a 4 stroke diesel is a myth that will not die."

National Fisherman was so unconcerned the ran tech articles for 2 issues ,
in an attempt to help working folks specify engines for their duty requirements.

Rather specific recomendations to follow.

Seems the 24/7 pro fish guys have problems the 100 hour a year yachtsman doesn't see.

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Old 11-20-2010, 08:22 AM   #43
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48
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Posts: 9,254
RE: Replacing a Ford Lehman SP135

Yup, some commercial fish boats do indeed suffer early engine demise (maybe after 15 years) , at near*idling RPMs for hours on end as they pull in and drop off nets and lines.* A properly set up fish boat has an engine big enough to move a load of fish in big seas that may well add 50% or more of the empty weight of his vessel. Most, not all, are set up with internal oil heaters to maintain crankcase temps above 200 during these long periods of very low RPM.

I met one happy fisherman this summer who replaced his very high hour 25 year old DD with a JD that weighed 1/3 as much - more room for fish and no oil drips in the bilge.*Many commercial*boats sit idle for*months on end in the PNW, so "winterizing" or having a buddy run them under load every month*is a must.

Charter fishing boats often have a kicker so they aren't forced to idle their big diesels. A boat I fish on has a 9.9 Merc*with the twin 180HP Volvos*shut down for the 4 to 10 hours per day of trolling.
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Old 11-20-2010, 05:25 PM   #44
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Replacing a Ford Lehman SP135

Charles:* We have ~7k hours on the engine and it runs great.* I'm *hoping to*get another 7K before we*have to do anything.* I agree with your post.**The thread started out as a hunt for*information on the what and what ifs when we do need to do an engine rebuild/re-power.* Once again I have learned a lot from and the people who contribute.* Thanks to all.

Hobo KK42
La Cruz, Nayarit, MX

-- Edited by Larry M on Saturday 20th of November 2010 06:26:34 PM
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Old 12-27-2016, 12:08 AM   #45
City: Rosebank
Join Date: Apr 2016
Posts: 12
Yanma/ Kubota Diesels Vs Case / JD Diesels

Just an observation from a retired Farmer. You hook a set of discs behind a JD /Case etc then hook up the same set behind a Kubota / Yanma diesel with similar HP Ratings the JD/ Case will walk away in a higher gear no trouble. When comparing the engines ,You will generally note that the JD/Case International will produce maximum power at 1700 to 1800 rpm the Kubota /Yanma will both need to be running 2500RPM +. I think these numbers might explain a lot.
If you want/ need long life diesels Non Turbo are way better than anything with Turbo because the stress is substantially less.
Have you ever seen a Turbo diesel working at night, if that doesnt convince you the non turbo will live longer,:: nothing will!
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Old 12-27-2016, 04:59 PM   #46
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City: Bellingham WA
Vessel Name: Hatt Trick
Vessel Model: 45' Hatteras Convertible
Join Date: Nov 2016
Posts: 1,550
"Any idea what the cost of a recon Cummins 6bt would be?"

Yes.....I installed a pair of them in 2014. $17k /engine. Another $6k or so will get you a Twin Disc gear. Mine are model 5050, 3:1. An earlier poster mentioned 6bt package deals available with Hurth gears but I haven't heard of this. I am completely happy with this power package. and Tony Athens' Seaboard Marine site can provide lots of info on this engine and it's applications.

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