? Survey Cummins 6cta 8.3 46' DA

[JC3]

Well i have found a 46' SR DA with Cummins in them. I know nothing about cummins. Have spent the last 4 months learning about Detroit diesels. These engines have about 400hrs on them.
Called about survey process after DD debacle and Fla Cummins said that they dont rec 3 day survey. Stated the survey would be one day depending on weather sea trail etc... What should i expect and what on the motors should i MAKE them do. I know Skip has his cathederal of thunder so any help would be appreciated. Boat looks very promiseing at this point. Frank, your thoughts would really help as would all you CATHEDERAL OF THUNDERING TORQUE guys! JC
Frank you will have some e-mail friday, i hope that is o.k.? JC

 

[Skip]

JC,
I have only put 147 hours on my 6CTA 8.3M3s, so I am by no means an expert. I bought her with 107 hours on the meters. My boat was traded in by the original purchaser with ~75 hours on the engines, 89 on the gen set, and the rest of the hours were spent moving theboat from Virginia Beach, VA up the Chesapeake to the Bay Bridge Marina in Maryland, then a host of demo rides..including a couple with me.
Really, really like my Cummins engines. They are simple to work on, are a nearly perfect match for the 420DA displacement and hullform, and thus far have proven to be utterly reliable. At 450 horses and ~1350 Ft/lbs of torque per side, I turn 22 x 26 four bladed props on a 2" stainless prop shaft. When you demo the 460, stand at the transom (braced, of course) and watch the amount of water that is moving with the engines in gear at idle RPM. It is really something..and as Frank W has posted many times, with Cats, Cummins, or any serious torque producing diesel, when you put the boat in gear you must be precisely aware of where you are headed...becuase you are going there, right now. When I put my boat in gear, the bow lifts about 2-3"...there is just that much torque. I cruise at 2100 RPMs, which gets me anywhere from 23 to 25 knots depending on load, wind, and current. WOT is 2600, but I rarely turn them up that tight. WOT gets me 32-ish knots, btu the fuel burn doubles over the 2100 RPM cruise...plus, at WOT, the turbo whine gets a bit annoying to the Admiral and crew. My average fuel burn over 147 hours was 20.54 GPH..and I do very little running in no wake zones.

I won't go back to gas engines in a boat.

If you proceed to Sea Trial, you absolutely want a competent Cummins tech along. This was the best money I spent. The kid from Cummins did oil samples, checked the temperature at each cylinder (discovered the #6, port, was overfueling, causing the cylinder to run 15 degrees hotter than the others); he also discovered that a preheater had been improperly wired at the factory, causing the starboard engine to smoke excessively at start up. The 24 month service on these engines is fairly extensive, and includes adjusting the valve lash. I had Cummins do that for me. I assume this boat runs ZF 280 Series IV transmissions, or something real close. Check to see if the oil filters have been cleaned annually. The filter cap is a hard to get to 22MM socket at the forward base of the transmission. If the white Cummins paint is intact on the cap, the filters have not been cleaned annually.

Do not be put off by rubber dust around the belts..these engines vibrate a lot and belt dust is normal. You'll want to inspect the racors to get a sense of fuel system cleanliness. The racors on my boat at sea trial looked like a timeshare condo for bugs. Not good.

Dominic wrote about low water flow in his Cats at idle. The pumps on the Cummins 450s will pump a LOT of water at idle.
Watch your temps as you put the engines under load. 165 degrees is normal. My starboard thermostats were slow to open, so I would get an overheating alarm (200 degrees) as soon as the turbo kicked in on that engine. New T-stats fixed the problem. Frank W wrote extensively at SRO about the overengineering of Cat cooling systems compared to Cummins...the Cummins cooling system works fine, but is not as robust as Cats, I guess. I have no Cat experience so i defer to "Obi-Wan Sea Ray"

At sea trial or demo ride, you will find yourself grinning from ear to ear when the Turbos kick in at 1800 RPMs and you get pushed back in the seat, and 50' and 14 tons of Sea Ray lifts and goes. It is quite a rush.

One often overlooked aspect of a diesel boat is the wonderful diesel generator. My 9KW Onan is powered by a 1.5 liter, 3 cylinder Kubota diesel that hums along at 1500 RPMs, uses something like a gallon of diesel an hour, and just pumps out quiet, reliable power, with far less CO risk than a gas equivalent (newer low CO Westerbekes perhaps less so)

Not sure I answered your questions, but keep 'em coming, I will do my best.

regards
Skip

 

[Petep]

JC, Those are great motors in that boat, with only 400 hours heck-they are brand new! Get the serial numbers off of both mains and call your local Cummins agent and have them run the numbers. Make an appt. to have a Cummins certified mech. come out and don't worry - he will know what to do. A 460 - Now we are talking! I also have a friend who is a boat repo guy and he just took in a '97 500 w/ the Detroits like you had looked at. I told him to put some specs on it together and I was going to send them off to you but, Those Cummins on a 460 are much better than those Detroits IMHO-As you may know I'm partial 'cause I had the 6CTA's on my last boat and the 480CE's on my current. Hope that helps!