What is with the dislike of Detroit diesels??

[StratPlan61]

Its pretty interesting, as I walk along the docks these past 5 years, from FL to MI, I always stop to chat with mechanics working on a vessel's engines. I talked with a guy one day in MS replacing the head on a new MTU in a Viking Sport Cruiser. Only a 100 or so hrs on it. I talked to another guy in NC that had just blown 2 MTU engines coming north from FL in a 76' Lazzara - had just sold his 56' Hatteras. He figured he had about $100k rebuild to resource. It is always newer engines - and never DDs as the problem. Yes, I understand newer boats mostly have other brands but with all of the older Hatts out there, I have never run across a mechanic making major repairs on old DDs.
My DDs smoke a little, but they seem to always start, sing along all day long, many days 12-15hrs straight, and use maybe a qt of oil at the end of the day. Not bad with an 8 gal oil capacity.

[jim rosenthal]

For many years, if you wanted diesels in a boat, you had very few choices. Especially for larger boats, DDs were the only choice available. There were larger Caterpillar engines, and Cummins, but most marine diesels were DDs.

As boaters wanted to go faster, DD began increasing the HP ratings of their engines, first by using bigger injectors, then by adding turbos, then inter and after coolers, etc. Some of this was done by DD; some by dealers such as Covington or J&T. The result, not surprisingly, was reduced engine life and higher maintenance costs, because these engines were making better than one hp per cubic inch. DD naturals are probably the closest thing to forever marine diesels that exist. But any marine diesel run at low outputs and maintained well will last a very very long time. The determination to wring the last hp out of a very old design is more than likely at the root of the reputation that DDs have. And they are heavy, and not very efficient, and they do leak oil rather a lot.

Parts ARE hard to obtain for some engines. Yes, there are a lot of DDs out there, but they are all old now, and even the ones that have had a major (or two) are old as well. And the technology is old. The two-stroke diesel was invented by Winton, in the thirties, and was made possible by the invention of the Roots positive-displacement blower, invented even earlier on. This is all very old machinery, good in its day, but obsolete now. Not non-functional, mind you, but obsolete. So you have to know that going in, if you buy a boat with them- good old motors, but old motors, and with periodic headaches. (and the 92 series have their own unique set of issues versus the 71s and 53s)

The choice is not about DDs, which are, after all, very old in many ways, on one hand, and electronic diesels on the other. There are a lot of good mechanical diesels around, including on the reman market, such as 3208 Cats and B and C series Cummins engines. It isn't a matter of two choices; there are more than that. Now, for NEW engines, they all have to meet Tier II emissions, so the choices are narrower.

Another way to look at it is that modern hulls are different in a lot of ways than boat hulls of the sixties and seventies; the quality may be different as well as the shape. In that context, it would also be fair to state that the change in propulsion equipment is greater in extent than the change in hull form and construction. Modern electronic diesels are quite reliable, although I would not have given you much for the DDECs and their brethren. And a good hull is a good hull, regardless of the shape. I do feel that the laminate schedule of a lot of modern boats is not as good as a Hatteras or other vintage good-quality boat. So maybe the engines have improved more than the boats themselves have.

[SKYCHENEY]

Don't forget, they still make brand new 2-cycle Detroits for the military. The only thing that made these obsolete was new government regulations.

[MikeP]

DD engines bad? Heck, I'm not crazy about Ferrari engines but that's what they put in the damn cars so we're just stuck with 'em. Life is what it is...

[Bayside Bert54]

Ordered the parts the other day to rebuild my 12V71TI (800hp) ... $24,000 for the parts. Labor estimate is 120 hours.

It's a good engine but stuff happens. This same engine was overhauled last January 2010 and only had 200 hours on it. The cylinder head failed introducing coolant into my oil .... so it's shot and needs another overhaul. Long story ... shop refuses to accept any responsibility.

Diesels are all expensive and have their issues ... the DD two strokes are pressurized so oil leaks need to be repaired or that tiny leak will spew lots of oil.

I was at the shop the other day and the mechanic pointed out a fuel injection pump for a MAN 10 cyl diesel ... $25,000 for the pump! Also, the other customer in the shop had replaced all the valves on his 3 yr old MAN engines due to poor design of the valves and they kept breaking. The Detroits are less expensive to maintain but burn more fuel and are more heavy. Unless you are using the boat for charter, it's usually not worth repowering with different engines.

Mike

[spartonboat1]

Any thoughts on the corrosion of the coolant passages??

I thought the long-time answer to this was "Nalco" or its equivalent added to the coolant or use DD Powercool, which I believes Nalco equivalent as a additive (not?). Someone pointed out to me on this site that the issue was not with the "N's", but with the turbo charged engines and involves microscopic coolant bubbles at higher power settings that create the corrosion (esp. near where the line seats?).

[krush]

Doing a "top end" overhaul on 2 Cat 3616's at work. Heads, injectors, pumps, rod bearings. Don't mess with the mains and don't pull the pistons or replace the rings. This is the 20,000 hour overhaul called for in the book.

Turbos are ever 6-10k I think.

Cost...don't ask But these are 7,000hp or so.

[shark 1007]

Count me as old school, I've been messing with boats for a long time. I repowered a Black Watch with 3116 Cats, a Rampage with Yanmars, my 41C with 3126 Cats and my 34C with Cummins. My old Pacemaker I ran as a charter boat had 871's and my recent 38 Special Bert had 6V71's.

The Bertram had a turbo leak, ingested mega soot and broke a top ring and scored a bunch of cylinders. It ran 20 knots all the way from Treasure Cay to Canaveral, smokin, but runnin. I made the economic decision to repower with 450 Cummins for resale and the boat has a new home.

Recently, I acquired a 52C that had been sitting 3 plus years. All batteries were cooked and the turd that was charging the owner 175 a month for maintenance and starting them had to have been rope starting them. I replaced the batteries, recirculated the fuel, cleaned the raw water intakes and pressed the button. They spun maybe twice and started immediately. (892's)

Old Detroits remind me of myself, they're old school, maybe a little heavy, smelly and reliable. Somehow I have a sense that if the Detroits will start, they will run wherever you need to go and not let you down. I don't have that feeling with the others.

They cost a bit more to run, are enormous, leaky and all that, but on a cool morning there's nothing that makes me smile like a DD starting.

Sadly, Jackie Bivens passed away last year. He was the guru of Detroit gurus and had developed the Bivens 8V96 that met epa standards as I understand, they were trying to develop a way to hook up a computer to a DD and verify things.

Detroits are the Galley Maid pump of diesels.

[bobk]

Ordered the parts the other day to rebuild my 12V71TI (800hp) ... $24,000 for the parts. Labor estimate is 120 hours.

It's a good engine but stuff happens. This same engine was overhauled last January 2010 and only had 200 hours on it. The cylinder head failed introducing coolant into my oil .... so it's shot and needs another overhaul. Long story ... shop refuses to accept any responsibility.


Mike

Mike, check your insurance policy. It might cover latent defects. Mine did.

Bob

[jim rosenthal]

What does a Caterpillar 3616 that makes 7000 hp go in.... sounds like a locomotive engine. Or a tugboat?