Caterpillar D334?? 1968 Motoryacht

Anyone have any info on this engine? I always thought this vintage Hatteras always had DD's in them. It's a boat listed for sale I was considering driving some time to take a look at. The surveyor I've used in the past said he wasn't familiar with the Cat D334. (He's been surveying for nearly 20 years.) Was this a special option or a likely re-power?

Thought/hoping someone in here might know. I know the older Detroit motors have their quirks - a bit loud/oily, but overall simple/old/reliable technology. No idea on the CatD334 with app. 3300 hours on the clock. Is the boat still worth considering?

Thanks!

That was a pretty popular over the road truck engine & was called a 1674 in the truck but was the same basic engine as the D334. They were a pretty reliable engine but was not the HD engine that the 1693 & the 3406 was (is) of 893 cu.in. displacement.As a truck engine they were at 2200 RPMs 270HP and are 4 3/4" bore & 6" stroke with 638 cu.in. displacement, same for the industrial. They were used in other industrial applications for whatever the customer needed it for besides as a Gen. set power plant.Off hand I don,t have the HP ratings for the industrial engines.

Appreciate the initial feedback. The D334s in the 68' Hatteras are rated @ 330 hp. with a 12 knot cruise and 16 knot top end. Spoke with a retired diesel guy who said he was familiar with the motor in long haul trucks but wasn't aware they were ever marinized. Said the hp vs displacement would indicate they would be long-lasting but also warned service parts might be an issue but he wasn't sure on that. And so far I can't find anyone who has owned a boat w/this motor so first-hand feedback is zip.

Dang.

A neighbor of mine has them in a 1968 Alaskan, he bought the boat in 1973. I think he has gone through typical wear items like starters, alternators etc. they have been trouble free. The boat cruises at 8 knots downwind ! They are very slow RPM motors and big displacement (not sure how big but big). He has an easier time tracking parts down than I do for my 1292's. The boat has cruised from Seattle to Panama multiple times.

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Originally Posted by Bertramguy

A neighbor of mine has them in a 1968 Alaskan, he bought the boat in 1973. I think he has gone through typical wear items like starters, alternators etc. they have been trouble free. The boat cruises at 8 knots downwind ! They are very slow RPM motors and big displacement (not sure how big but big). He has an easier time tracking parts down than I do for my 1292's. The boat has cruised from Seattle to Panama multiple times.

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Thank you. This is exactly the kind of feedback I was hoping for.

You might find some information on the boatdiesel.com forum on these. 333s and 334s were low-speed, low-stress engines built by Caterpillar- not many ended up in boats but from all I have seen, they were usually installed in large motor yachts with modest cruise speeds. In their day, they were well-regarded- fairly easy on fuel, not temperamental. You'd want a survey and all that, but if they check out okay I would not hesitate to buy a boat with them installed.

Interesting measurements on bore and stroke- very undersquare, they must have amazing torque.

Oh, and these are likely original fitment. In that size class, Hatteras would have installed what the buyer asked for, as long as it wasn't too weird. These might have even been a factory option back then. Which model Hatteras are they installed in?

I had D333's in a 57 Chris Connie, 1963 boat . Boat ran well both on plane and at hull speed. IIRC we got about 2NMPG at 9.5K and would plane at 18-19 K without any issues. I do recall the dry turbos looking real scary and glowing in the dark with heat . Simple engine - governor and injection pump was one ass'y . Had to have one rebuilt not too crazy expensive.........Pat

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Originally Posted by jim rosenthal

Oh, and these are likely original fitment. In that size class, Hatteras would have installed what the buyer asked for, as long as it wasn't too weird. These might have even been a factory option back then. Which model Hatteras are they installed in?

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Hi - sorry for the delay in responding. The boat is a 1968 44-foot Hatteras MY. Broker indicated little knowledge about the motors. Would want a full mechanical survey of course. Just wasn't sure if I wanted to jump in that far if the motors were totally obsolete. Sounds like they were reasonably well regarded and basic maintenance is still possible.

Broker has it listed as a 12-knot cruise and 16-knot top end so won't be winning any races but I recall doing a test run on a 50 foot Hatteras of similar vintage and was really impressed with the stability of these boats. SOLID. Now that I'm in my late 40's going fast isn't so important. I want a safe and comfortable ride.

Was originally looking to a classic 50/53 MY but the 44 seems like quite a bit of boat as well. (Sold our classic 41 foot CC, bought something smaller, and now regret doing so. Was going to go with a Hatteras years earlier before I found the CC. (It was a lot cheaper) So many boats, so little time/money...)

The 44 is a really nice boat. I would not let the engines scare you; if kept up, they should be fine. No one was making modern lightweight high-speed diesels at that time, so these are about the same weight and power as DDs or Cummins 903s, I wuold guess. See the boat, and see what you think. You should be able to find information on who has parts for those engines on line, most likely via boatdiesel.com. Good luck and keep us posted.