Cummins QSD 150 hp / R-25

[acustis]

I was responding to the original thread posted. I am looking at Henry's specs and his location. Sorry about the confusion.

[Doryman]

[IT-SEA-BIT-C]

I sucribe to passagenaker and Steve's articles are entertaining , and somewhat informative, just take most of it with a grain of salt . I 'm just trying to say if you maintain diesels well they are pretty darn hard to hurt at any RPM & will last longer than anything on the boat , cept mabey the anchor

[thataway]

I am going to have to disagree with it-sea. The older type of tractor engines which were low speed, non turbo were almost bullet proof. But they do have problems and require careful maintance: filtered fuel, oil changes in the injection pumps (Simm's pumps). Today most of what you buy are highly turboed, they live in a salt air environment, they are often not run for months and then run hard. Some marine engines are tractor conversions--but many are not. The engines as in the Ranger 25 are turboed, they run at high speed (Acustis notes he has run one at over 4000 RPM). These engines have to be run up to temperature and the turbo spooled up to prevent carbon deposition (and some other problems)
I have had personal discussions of Bob Smith of American Marine Diesel, who has been one of the largest distributers of marine diesels for many years about the longivity of the high speed, lightweight diesels, and they are not going to give the 10,000 to 15,000 hours without problems which the slow tractor engines have in the past. 2,000 to 3,000 hours before major work appears to be common--if they are not abused. If you look at many of the high speed boats running diesels often they have been replaced or rebuilt in a few years or a few thousand hours. The sport fishers who run high speed turboed engines; rebuild the turbos every few thousand hours on a regular basis. The boat diesel running a boat at semi-displacement speeds is like a truck going up a steep grade all of the time.

Yes, you can run the engines at lower speeds, but you have to bring the engine up to operating temperature, plus every few hours bring up to at least 85% of WOT.

[IT-SEA-BIT-C]

As funny as it may sound I also have to AGREE , with Bob disagreeing with me.( I highly value your opinions Bob ) Ihave 3 newer machines with turbo's and i gotta tell ya between besides the salt water enviorment , you wouldn,t believe the the enviorment they live in , crappy old fuel , usually watter logged, dust plugged raditators,cold temps in winter, and the list goes on............. So thats what i base my posts on. believe me when i tell you it"s not easy keeping up maintance of a small fleet of equiptment, especially when the push is on. stuff goes way past due, looking back on most of my posts my fingers are not really gettin what my brain is trying to say on the screen, i"m realizin that i need to work on that or i"ll have to stop posting, cause it isn"t commin out right. mabey i should have just said todays diesels if maintained properly & operated correctly will be very reliable . in my exp.just the oppsite generaly occours & the motors are still unbelievably reliable. tryin to help but i"m thinkin about hangin up hat sorry brats for any bad advice it was never intended ............... John