Detroit Diesel

[deepthought]

we have a 2-71 in our sailboat.

[Lepke]

I have twin 671 naturals. I love them for the reliability. Especially the 71 and 53 series. 92s and 149 don't run as long. I'm looking for a 271 generator to replace my Perkins and Onan generators. 71 generators run at 1200 rpm. Last forever.
You see DDs in bigger, older sailboats (usually 371 0r 471), tugs, and as generators in ships. In WWII, all the LCIs were powered by quad 671s on each shaft. Marine Corp tanks had 671s along with most landing craft and ships boats. All the WWII built ships I've been aboard had multiple 671s running pumps and generators. Lots of older logging equipment and some tractors have 671s.

If I was going to build a new pleasure boat (not under the Tier rules) I would find some Detroits, rebuild and install them. What I like is the reliability, all mechanical, no injector pump, no electrical needs beyond starting, and parts available everywhere. In the right hull, they are very economic.

[Bill Seal]

Originally Posted by Lepke

I have twin 671 naturals. I love them for the reliability. Especially the 71 and 53 series. 92s and 149 don't run as long. I'm looking for a 271 generator to replace my Perkins and Onan generators. 71 generators run at 1200 rpm. Last forever.
You see DDs in bigger, older sailboats (usually 371 0r 471), tugs, and as generators in ships. In WWII, all the LCIs were powered by quad 671s on each shaft. Marine Corp tanks had 671s along with most landing craft and ships boats. All the WWII built ships I've been aboard had multiple 671s running pumps and generators. Lots of older logging equipment and some tractors have 671s.

If I was going to build a new pleasure boat (not under the Tier rules) I would find some Detroits, rebuild and install them. What I like is the reliability, all mechanical, no injector pump, no electrical needs beyond starting, and parts available everywhere. In the right hull, they are very economic.

I can't believe you pulled out those wonderful 100GPH Sterling Viking II hunks of cast iron and stuck in the power plants from the old USCG 40 footers.

The 2-71s were used to run the compressors on the old diaphone fog signals.

[Scott Berg]

Most of the boats I captain have DD's; range from 6-71's to 12V92's. Noisy and not as efficient as modern CATS and MTU's but easy to work on. Can't miss the sound when you fire one up...

[Lepke]

Originally Posted by Bill Seal

I can't believe you pulled out those wonderful 100GPH Sterling Viking II hunks of cast iron and stuck in the power plants from the old USCG 40 footers.

I didn't, but I believe they lasted until 1973. The CG derated the engines after WWII. The boat made 22 knots and after the war the CG limited them to 15 -18 knots. I think the current engines were installed used because they were originally white under the Detroit paint and are 1947 & 1948 manufactured Gray Marine engines. Probably pulled from some yacht getting new or bigger engines. Because of the liners I pulled out and other parts, I don't think the 671s were ever overhauled in 63 years. I was able to trace way more than 20,000 hours since 1973 and no idea of their hours before that. Many parts I know to be different between DD and Gray are still original, like the exhaust manifolds and of course rods, cranks, heads. These engines are what I have found to be typical DD 71 series reliability. My first pair was about 1963. I love 'em.
In my youth I ran old slow turning diesels that were also reliable for the same reasons, no injector pump or electronics.

[R1Guy]

I have a power boat, not a sailboat. However mine has twin Detroit Diesel 6-71 Naturals. Its a 1977 Viking and the engines are original to the boat. They are very loud. I've heard they can be smokey. Mine are quite nice and clean surprisingly!

[drcot3]

Got the same engines 6/71N a little dirty some oil blown out though breathers otherwise great engines same as Gardner engines first-class no greater compliment I can say.

[nhschneider]

When I got out of high school (a VERY long time ago) I got a job as a crew on a Phil Rhodes-designed 65-foot steel motorsailer that was fitted with a 471. We cruised up and down the west coast of Mexico and never put the sails up once. As I recall, I jumped ship in La Paz, went back to my parent’s house and met my wife, to whom I’m still married, 45 years later.

Sorry, I don’t know what all that has to do with Detroit Diesels!

Fair winds and calm seas.

[Diesel Bill]

Well, I made the mistake of looking at boats for sale on E-bay yesterday. Like I need another hole in the head. Was thinking if I got to old and stove in to sail anymore. I came upon a 57 foot Chris Craft Connie, 3 staterooms, 3 heads and a pair of 8-V 71N series. and a brand new gennie. I almost told the wife to go back to work as daddy needs a new boat to play with. Asking price was $65k. Only thing that shut me down was a wood hull. No, I'm not afraid of wood but I do realize the tremendous amount of love a wood hull requires. But I was in full drool mode over 2 Detroits to play with and love. I can run the racks with the best of them. Sweet, sweet music. Oh, and the other thing was the boat is in N.Y. and I'm in So. Cal. Well a guy can dream. I hope whoever gets it will appreciate the D.D. engines.

[nhschneider]

Originally Posted by Diesel Bill

Well, I made the mistake of looking at boats for sale on E-bay yesterday. Like I need another hole in the head. Was thinking if I got to old and stove in to sail anymore. I came upon a 57 foot Chris Craft Connie, 3 staterooms, 3 heads and a pair of 8-V 71N series. and a brand new gennie. I almost told the wife to go back to work as daddy needs a new boat to play with. Asking price was $65k. Only thing that shut me down was a wood hull. No, I'm not afraid of wood but I do realize the tremendous amount of love a wood hull requires. But I was in full drool mode over 2 Detroits to play with and love. I can run the racks with the best of them. Sweet, sweet music. Oh, and the other thing was the boat is in N.Y. and I'm in So. Cal. Well a guy can dream. I hope whoever gets it will appreciate the D.D. engines.

If I were interested in that boat (and I must admit that it sounds intriguing), I’d offer them $20K and I wouldn’t be surprised if they accepted that offer.

Fair winds and calm seas.

[Pelagic]

Ran a number of boats with 6-71's..... Tugs, fish packerd , pilot boats. Set up as Gens. Tandom mains

What I always disliked about their design, was that the fuel lines, were internal inside the valve cover.
That meant that a fuel leak could contaminate the oil, overflow the sump and scavage it into a runaway engine.
Not Nice!

[newhaul]

Originally Posted by nhschneider

If I were interested in that boat (and I must admit that it sounds intriguing), I’d offer them $20K and I wouldn’t be surprised if they accepted that offer.

Fair winds and calm seas.

not gonna go cheap they are rare and sought after vessels . And nothin beats those 8-71's

[Jrmcnabb9]

Hello.
I need alittle Help. I have one of these ole early 70’s Detroit. It’s a n471. I have it in a small 32’ shrimp boat. Single screw. Love it it’s the best. “If there’s no oil under them there’s no oil in em”.Lol
How ever the 471 is down rn with water in oil. I tested the oil cooler, test for leaking injector cup. That was not the prob.
Today I attempted to remove my head and it would not budge. I removed obviously the head bolts, the two bolts at the front of the motor and two bolts in the rear of the head. Has anyone here ever had such a problem w the head stuck to the top of the block?
. Anybody’s words of wisdom would be appreciated.

[Lepke]

If someone used a lot of sealer, the head can stick. It can be pried off. Sometimes with a custom bar attached to some head bolts to give leverage. Also use a hammer and tap from the bottom up.

I've had DDs about 60 years. I also rebuilt many. Water to oil head gasket leaks aren't common. If it's heat exchanger cooled, my first guess would be the seal in the salt water pump or the heat exchanger. Did you pressure test the coolant side?

[Jrmcnabb9]

Thanks for reply lepke.
I have removed and tested the oil cooler and hydro tested the head with injectors out to check injector cups. That was all good. She got hot about 2 yrs ago but didn’t show signs of cracked head Then. It sat up for about 3 mo before it showed water in oil. Now I’m hoping head gasket kit. But I can’t seam to get it off. On each end of the 471 there is hardly no tolerance I’m thinking it’s rusted in but not sure I want to make sure there’s no bolt somewhere before I get to rough w it.