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I am looking at a 37' boat (a mid 70's heavy glass hull) that has twin Detroit 6v53 engines. I believe they are rated a 200 HP each.
Anyone have any experiences with these engines. My first thought was to take them in to my local dealer and completely rebuild them. My concern would be enough HP for this boat. They seem to have a good size 4 blade prop. Not sure of the size.
I am not quite sure how this works as far as wheel size, HP, prop size gearing, etc... to get a idea of performance.
Would I be better to change engines and go to something more current engine?
I'd repower when they quit. Rebuilding a Detroit isn't economically justified these days, the motors are great ones, seemingly run forever, but when you spent 25k on rebuild they aren't worth that.
My Detroits are bein pulled out as we speak .I'm repowering with Cummins.
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I had 6v53 in a 46 foot wooden deadrise in the Chesapeake bay,,they were super dependable and very reliable,,,also very fuel efficient. I ran 14-15 cruising and 19-20 wot. could run the bay all day trolling and running and used only 50-75 gallons of fuel. They should push a 30 + boat with no problem.
While you did not mention the type of boat; a 200HP engine is not going to move anything that size very fast. The 6v53's have plenty of torque; but 200HP is not much. As for rebuilds; sorry to disagree with the poster above, they can be rebuilt several times with ease and not 25K either. By the way 6V53's are loud because of the very high compression ratio they run on.
Good engines for there era! I'd repower if it is a fesable option and you love the boat. You probably won't get your money back on the repower if you decided to sell .
Those motors (in normally aspirated form) seem to just run forever. They are loud, as all two stroke Detroits are. That motor saw lots of industrial use. Its 318 cubic inches. I would run them till they break. Which may be a long, long time. Then, think about some Cummins. What is the Hull?
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Those old 2 cycle detroits run forever , as everyone has said. I have had quite a few in heavy equipment and used them for years. I really floored by how much people say they have spent on rebuilding detriots. 25K--WOW. The rebuild kit for a 6v353 is about 1K. I have personally rebuilt several 53 series engines,and the parts are dirt cheap. If the engines have alot of hours on them you may consider trying to find someone to pull the heads and just change the pistons and liners- instead of complete rebuilds- which involves tearing motor down completely and replacing all gaskets - seals and bearings. I did this a couple of times and it improved the power of the engine tremendously, and it was fairly inexpensive. This really works well where you do not have to pull the engines.
If I were looking at a boat with detroits , and they ran fine and the boat had sufficient power, I would leave them alone.
There is a local 37 Topaz with the 53's in them but they are the T's rated at 300hp. I have considered taking a swing at it. By the listing it isnt as fast as one with the 3208's (375hp) but what the heck, I would gladly run 20 knots every day rather than 24 knots on just the good ones. Parts are cheap for the DD's and they sound great.
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I had 6v53 in a 46 foot wooden deadrise in the Chesapeake bay,,they were super dependable and very reliable,,,also very fuel efficient. I ran 14-15 cruising and 19-20 wot. could run the bay all day trolling and running and used only 50-75 gallons of fuel. They should push a 30 + boat with no problem.
VIC, This guy said it best.....60 gal of fuel, with loud engies.....Cummins 4 BTA's or Cat's 3116's burn 9 GPH @ WOT worst case, at troll 1 gph @ cruise 4 gph...
Cummins 4 BTA's are cheap and d~mn good engines...I am a engine builder, just my thoughs Greg,,,Oh and my hearing is going @ 50 from loud engines. Not to be smart but I would think about this.
6v53s are great engines. The are loud because of the superchargers that create a high pitched whine. Run them until they break. The issue I see is the hp from these engines. Will not likely plane a 37 foot boat. Depends on the hull. I had 8v53s in a 38 hatteras motor yacht. They were rated at 285hp, and it was a heavy boat. Cruised at 15-17 knots at 25 gph. Top end, in cool weather with a light load and clean bottom, 20 knots. Not sure what type of boat you are looking at. Get an engine survey before you buy.
all 2 stroke dd's have blowers, not superchargers(even though its a root type charger it doesn't build much manifold pressure). Even with the N designated code natural aspirated. The forced inductio T and TA are blower with additional turbo. The 53 were used quite abit in coast guard boats. I personally love detroits, there unstoppable, loud because there a 2 stoke, you can put muffs on and quite them out. Cheap to run cheap to rebuild.
DD are supercharged, kinda loud and at 200hp, should run a long time....twins will push your boat at reasonable speeds....in frame rebuild is the way to go...cheapest of all the diesels, they do tend to leak alot of oil, especially when they get some hours on them....serious torque though
I'd repower when they quit. Rebuilding a Detroit isn't economically justified these days, the motors are great ones, seemingly run forever, but when you spent 25k on rebuild they aren't worth that.
My Detroits are bein pulled out as we speak .I'm repowering with Cummins.
I have spent decades driving DDs in trucks. I am not familiar with them in a marine application. From what I am reading, the 53s were great engines in boats. In the 1970s the DDs in trucks were throw away engines. $25K for a rebuild is robbery.
If you like the boat and the engines are in good shape, buy it and run the engines until they blow. Then repower with four cycle turbocharged engines. Structure your offer with the repower in mind.
DD are supercharged, kinda loud and at 200hp, should run a long time....twins will push your boat at reasonable speeds....in frame rebuild is the way to go...cheapest of all the diesels, they do tend to leak alot of oil, especially when they get some hours on them....serious torque though
Leak alot of oil?
Detroit Diesel was the engine of choice in construction equipment up to the mid 80's, and some did leak oil, but mostly from the breather tube, and that was due to over idling.
I have seen it too many times in a Marina, start the engine up and let it idle for a half an hour, which is the worse thing to do with a 2 stroke diesel, once it warms up, crack the throttle up over 1000 rpm, if you don't want to hear the noise, don't start the engines until your ready to go. all that idling causes blow by [oil going past the cylinders]
Idling any Diesel for long periods, or any engine is a bad habit, but in a 2 stroke Detroit it can cause premature failure, because when at idle they run too cool.
I have had a lot of luck with all the V6 Detroits except the 6-92's. Never had them. But 6-71 and 6-53 are just about the most reliable engine ever. I think I recall Detroit started these series back in the 1920s. And that other guy is right, if they are burning oil, sleeve them, new pistons and they will probably last longer than you will. If they are not using too much oil, I would just run them.
It has been mentioned several times about these engines being loud. Are they like ridiculously loud? Is there a way to quiet them down? ( other than passing out hearing protection )
Would I be wise to have my local dealer turbo charge them if possible and bore them out for more hp during the rebuild?
If I increase HP that would allow me to turn a larger prop. Would I have to change gears to get more speed? Not sure how this works.
Would be happy with a 20 knt. cruise.
Detroits 6v53 ? 
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