What is with the dislike of Detroit diesels??

[power convert]

Over the weekend I found myself at the hull truth. When searching around I came across many negative comments for DD. Poor fuel consumption, noisy, scarce parts for some engines. Is this because they are comparing new technology with older technology. It seems from some posters point of view if it isn't Cummings or Cat it is not worth anything.

Furthermore, I talked with a family friend who owns a DD dealership and his comments were surprising. He didn't say the two strokes were bad, but mentioned block corrosion in the coolant passages as a concern with the older engines. Also, he talked of the cost to repair his 6-71T even at his cost. He then went on to suggest that I had better have the money ready for new Yanmars.

After reading David Pascoe's site he is still very much in favor of DD, but he only talks about the newer 92 series engines.

Are there ways to determine if there is corrosion issues?
Would an engine survey be able to give this information?
If a leak in the block occurs I am assuming that it is time for a new block and thus maybe time to look at re power options?

Finally, is Hatteras and DD like an arranged marriage? It is the only option at the time so you better learn to love it.

[GJH]

THT is the first place I'd look for outboard motor advice and opinions , and the last place for diesel advice. Mostly hearsay there.

[yachtsmanbill]

Finally, is Hatteras and DD like an arranged marriage? It is the only option at the time so you better learn to love it.


Like a shotgun wedding! An old DD only needs air, fuel and water and a way to spin it to start. Take a new unit with an electronic monitoring system and get the board wet when youre 100 miles offshore and see what the expurts on THT think... ws

[SKYCHENEY]

There were a few old Hatts with Cummins but most were DD's. Now it's Cats. Hatteras has always stuck with their suppliers. Look at any of the components over the years and they rarely changed.

[saltshaker]

Like Bill said Detroit's were the only option, not just from Hatteras but from most manufacturers at the time. They also were good choices until Detroit started cranking up the HP and shortening service life. They are noisy, dirty, very inefficient and have a shorter service life compared to modern diesels. If you are buying an older boat that is part of the trade off. They still are cheaper to keep than pulling them out and re-powering with new power. It also depends on what Detroits your talking about. A set of well maintained Detroits will give great service providing they aren't high HP versions. A 525HP 12V71N will easily run 10K hours if cared for. A 1000HP 12V71TI will have a hard time making it to 2K hours. Parts are becoming more scarce and the cost keeps rising but they are still much cheaper to repair than most any other brand. Try pricing some parts for those Yanmars and see if you think they are cheaper to own. The issues with the Detroits become more real when you look at the big ones like the 1000+HP 12V92's or 1300+HP 16V92's. When your looking at paying 75K-130K to rebuild them every 2K-2.5K hours, providing there are no major core issues, and a fuel burn that is 20-25% higher than a similar HP modern diesel, that's when many buyers shy away. On the other hand, you don't want to be on the recieving end of a bill to major a pair of modern Cats, Mans, MTUs, Volvos etc.

[power convert]

Any thoughts on the corrosion of the coolant passages??

[Avenger]

Depending on the boat Cummins or CAT may have been available options.

This is like a Ford vs. Chevy thing, or that other thing they say about opinions. There are no "cheap" marine diesels, some are less cheap than others but they're all potentially costly to service and repair. The only thing I can say to those that dislike Detroits is there must be some reason that they've been making them since 1938.

[Genesis]

If you run properly-balanced coolant or a water/inhibitor mix it's a non-issue. If you don't.... well guess what - same issue with any engine.

[Passages]

Since you are familar with Pascoe, somewhere he writes that the DD 6-71 (@ <410 hp) is probably the best marine diesel ever made.

[power convert]

I guess I was most surprised with the response from the DD dealer of his own brand or maybe he was just sugesting to procceed with caution.

[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?

[REBrueckner]

"Are there ways to determine if there is corrosion issues?
Would an engine survey be able to give this information?"

I'm not generally aware of old DD's having any special corrosion issues....except here and now...I've never heard that as a criticism. Corrosion of the raw water (salt water) side is controlled by cathodic zinc plugs; Corrosion on the fresh water coolant side is controlled by chemicals...either in the coolant additive like Nalcool or via antifreeze additives. DD coolant systems require HEAVY DUTY antifreeze, that is, it says that and "Detroit Diesel" on the container. ONly wet liner DD's might be subject to crevice corrosion which is not a chemcial corrosion but pitting due to cavitation...Which are the wet liner DD....53 and 92 series, not the 71 series....Nitrites prevents wet liner cavitation pitting.

I don't know the direct answer to the posted questions but let me take a shot to help and then the experts can criticize my observations:

If you inspect engine coolant and find any of these I'd be concerned:

(1) its all water and rusty and dirty
(1a) you observe an overflow tank and can't see what's in it because it's all rust colored with sediment,
(2) It's antifreeze but acidic,
(3) you have the coolant analyzed by a lab and they comment "Ugh".
(4) If you ask the owner when the last time the coolant was tested or changed and you get a blank stare in response,
(5) If during the sea trial, when the engine is run at WOT, and overheats or cannot be run at WOT because of rapid temperature rise (there could be many causes of this).

Engine Survey: In general, if a lab test analysis of engine coolant shows the coolant is ok ...meaning it is NOT acidic, is in the proper alkaline range, and has the propr addivitv es without oil, likely you are ok....

[Bayside Bert54]

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

Bob

I appreciate that Bob ... My Travelers Insurance does not cover a Latent Defect. Of course, the policy doesn't mention this. The documents provided by the claim department do.

The more insurance I have, the more I realize what a total ripoff it is.

This only thing more fun than being ripped off by Saunders Yacht Works of Orange Beach, AL is having insurance and realizing that this particular thing is not covered.

All I can say is ... what goes around, comes around!!! And I will work with my attorney to be sure it "comes around" for Saunders.

Mike

[REBrueckner]

Here are my prior posts on DD engine coolant:

http://www.samsmarine.com/forums/showthread.php?t=11974&highlight=engine+coolant

http://www.samsmarine.com/forums/showthread.php?t=11757&highlight=engine+coolant

and I am reminded I do not recall any prioir discussions in these forums regarding DD engine corrosion....

[power convert]

Thanks for the links Rob very informative. When I was talking with the DD owner I had asked him about a 53 series engine and because of the wet liners he had more concern for the corossion issue. I am correct in saying that block corossion in not much of an issue, but wet liner corossion could be possible?

[Genesis]

Liner erosion is not the same thing as "corrosion" per-se. Wet liners are subject to erosion damage from cavitation but you need to keep the coolant balanced properly in any event.

It's all trade-offs; I personally like the wet-liner motors. All diesels are intolerant of overheats and the wet liner motors have more to break if you do it, but a cracked head is bad enough news anyway, so the best advice in that regard is "don't."

[saltshaker]

I appreciate that Bob ... My Travelers Insurance does not cover a Latent Defect. Of course, the policy doesn't mention this. The documents provided by the claim department do.

The more insurance I have, the more I realize what a total ripoff it is.

This only thing more fun than being ripped off by Saunders Yacht Works of Orange Beach, AL is having insurance and realizing that this particular thing is not covered.

All I can say is ... what goes around, comes around!!! And I will work with my attorney to be sure it "comes around" for Saunders.

Mike

Travelers usually offers coverage for latent defect. I have it on my policy and a friend just had a claim with Travelers that was covered under latent defect.

[Bayside Bert54]

Travelers usually offers coverage for latent defect. I have it on my policy and a friend just had a claim with Travelers that was covered under latent defect.

Thanks again Jack ... I fired off an email to my agent asking how it is that I do not have this coverage. I also let her know that I will be canceling all of the Travelers Insurance that I have personally (auto, home, marine, umbrella) and several I have for my business. They can kiss my bumper.

Mike

[RFly2Dive]

Back in January I mentioned I was in the midst of a repower of my 1991 52' CPMY due to both engines (8V92 twin turbo 720hp) failing. I am in the process of repowereing with QSM11's from Cummins with warranties till 2014. Hopefully this repower will be done by mid May. If interested I will be posting pictures here or will be posting on photobucket with a link to them. Great debate and I will also be replacing my generator with Cummins and an instant on 220V water heater. Overall I am looking forward to raising my waterline due to the weight savings and lowering fuel consumption.

[ron6785]

Over the weekend I found myself at the hull truth. When searching around I came across many negative comments for DD. Poor fuel consumption, noisy, scarce parts for some engines. Is this because they are comparing new technology with older technology. It seems from some posters point of view if it isn't Cummings or Cat it is not worth anything.

Furthermore, I talked with a family friend who owns a DD dealership and his comments were surprising. He didn't say the two strokes were bad, but mentioned block corrosion in the coolant passages as a concern with the older engines. Also, he talked of the cost to repair his 6-71T even at his cost. He then went on to suggest that I had better have the money ready for new Yanmars.

After reading David Pascoe's site he is still very much in favor of DD, but he only talks about the newer 92 series engines.

Are there ways to determine if there is corrosion issues?
Would an engine survey be able to give this information?
If a leak in the block occurs I am assuming that it is time for a new block and thus maybe time to look at re power options?

Finally, is Hatteras and DD like an arranged marriage? It is the only option at the time so you better learn to love it. Mine are 38 years old have never been broken into 8/71 N's and don't smoke have a gaxzillion hours and run just fine. They use alot of oil aprox a quart per 10hr. day at 14-1500rpms and they leak , but if they will start they will run and on just about anything slightly combustible. I've been cruising the Bahamas all winter and I can't tell you how many new yachts are down here and they can't get an engine started or won't run properly and nobody can tell them why. So they end up limping back to florida to get them fixed. Alot of these Bahamian fishing and lobster boats are still running 6/71's with 30,000 hours on them

[rsmith]

When the end of the world comes there will be a 2 cycle DD running somewhere.

[Boatsb]

No when the end of the world comes there will only be DD 2 strokes running.

[krush]

i heard when teh worldz ends, 2 stroke DD will run on dead hippies and enviro-nazis.

[captddis]

i heard when teh worldz ends, 2 stroke DD will run on dead hippies and enviro-nazis.
Why not start now?

[madhatter1]

They are starting to pile up now although not as fast as we would like. Soon corn prices will come back down when the more sensible alternative fuel is readily available. When a certain "documentary film maker" kicks can I convert my engines to run on the new flex fuel?

[rsmith]

i heard when teh worldz ends, 2 stroke DD will run on dead hippies and enviro-nazis.


They need to be converted to soylent green first.

[yachtsmanbill]

When the end of the world comes there will be a 2 cycle DD running somewhere.

Spin 'em over and spoolem' up! ws

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