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Detroit 671 TI rebuild

Discussion in 'Ocean Yacht' started by Boomer, Jun 26, 2018.

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  1. PacBlue

    PacBlue Senior Member

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    Our 310hp J&T 6-71N was trouble free and my all time favorite Diesel, and the sound of it lighting off at Oh-dark thirty can never be wiped from my memory “chip” , miss that bark!
  2. Boomer

    Boomer Senior Member

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    Negative...lol...beyond my limits
  3. Boomer

    Boomer Senior Member

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    Well this winter we will get the other head pulled and redone...while in there the mechanic will poke around to make sure no other problems manifesting themselves
  4. chesapeake46

    chesapeake46 Senior Member

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    (+1 )
  5. Capt J

    Capt J Senior Member

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    I ran a 41' Viking SF with those and while they were great running motors, the exhaust noise on the FB at slow speeds was UNBEARABLE. You really needed ear plugs.

    The best detroits I ran were detuned 8v71TI's, they were rebuilt with 110 injectors instead of 130's and they ran crisp and clean and had great throttle response at all speeds, especially docking and slow speeds.
  6. PacBlue

    PacBlue Senior Member

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    I believe the 41 Viking's did not have the J&T 310hp 6-71 Naturals, they had transitioned to the J&T 6-71TI's rated at 450/465/485 hp.

    The 41 was the next evolution of their previous classic 40 Viking which did have the J&T 310hp 6-71N engines. During my first trip to South Florida looking for a Sportfisher in 1980 we found a 40' Viking with a Marlin Tower and tried to make a deal but it fell through. Recall the engines were a real tight fit in the 40 and you could barely get your hand between the top of the engine and the underside of the salon floor. I then became aware of how hard the South Florida weather is on boat cosmetics, had a hard time finding something that wasn't in need of a "Face Lift".

    The 41 was a redesign to fit higher hp and go faster, the next generation. Exhaust noise control was up to the builder, the tone could be knocked down with a decent linear muffler, but Viking was still under control by the old man, and they didn't spend on equipment like they do today under junior's watch.

    Our 38 Blackfin with 6V-92TA's was unbearably loud, after 30 minutes I was practically ready to jump ship. Then I realized my Dad, who was a lifetime machinist, was practically deaf in at least one ear and missed that issue on the purchase sea trial which I could not attend. Blackfin made no real effort to deal with exhaust noise on that model, it was a joke.
  7. cleanslate

    cleanslate Senior Member

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    Ok...yeah me too, I can change the filters and fluids but not into opening things up on the motors...yikes!
  8. Capt Ralph

    Capt Ralph Senior Member

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    Anybody remember that George Burns song: If I was sixteen again??
    I'd still be learning about 71s but maybe, maybe, MAYBE, would of learned about A frames and chain falls earlier.

    Nothing beats working on 71's, but maybe, maybe 53's. 53s were so compact and freaking temperamental.
    53s always impressed me with what they could do. The ultimate Screaming Jimmy.

    Just picked up a new customer asking just to reduce some oil leaks. I did honestly warn him that his 8V71s were not running correctly if they did not leak and it takes many hours to reduce or even come close to stopping Detroit's from leaking oil.
    Looks like my final retirement job.

    Oh, he has an old faithful dawg. I told him I would only work onboard with his faithful ole friend to help. We agreed on all.
  9. Capt Ralph

    Capt Ralph Senior Member

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    One day I will have to start a new thread, Dawgs on da docks. Gad I luv them all. Corrupt a few and just spoil the rest when I can.
  10. Capt J

    Capt J Senior Member

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    I just ran a set of 6v53 TI's for 21 out of 24 days. Mostly 12 hours a day. They have 400 hours SMOH and oil leaks everywhere......from the blowers......from the valve covers (who thought of only 2 valve cover bolts in the center of the valve cover was an idiot), from here, there and everywhere else. They ran good with no issues...but only ran them 1630 rpms or less (displacement hull that was WAY overpowered, 6v53 N's would have overpowered it)…..but one thing with 53's is you NEVER want to see 205F on the coolant temp gauge. Give me 71's any day of the week.
  11. Capt Ralph

    Capt Ralph Senior Member

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    4 years ago I started playing with exhaust deflectors. They are still there and working fine.
    Sadly, nobody has come up with anything new.
    If anybody has, please pickup on my old thread or start a new thread.

    https://www.yachtforums.com/threads/poor-mans-exhaust-silencer.23691/
  12. Capt Ralph

    Capt Ralph Senior Member

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    Wet liners, just like the 92's are not forgiving to overheating. It takes time and lots of hootch to stop (greatly reduce?) Detroit oil leaks.
    Blower and valve cover leaks may look different but mostly are the blower or slobber leaks. Fresh valve cover gaskets to a great job.
    Leaking governor rod tubes and turbo throttle delays get the valve cover gasket hit also.
  13. boatpoor

    boatpoor Member

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    35 years in the construction business has forced be to own, maintain and operate many Detroits. Until the late 80's they were the best way to power most construction equipment and some of the most dependable power plants on the job site. We had 53's 71's and 92's and they all had their place. We had an old Hobart welding machine with a 2-71 that started the rest of the fleet on many cold mornings. The one thing they all had in common was they leaked oil. They were Detroits and we accepted it, but I have owned several boats with Detroits and I won't tolerate an oily bilge, so between airseps and constant maintenance, my marine Detroits don't leak. It's not easy but it can be done. I'm currently running a pair of 6v92 TA's that are as clean as any Caterpillar or Cummins we own. Personally I like Detroits and as long as parts are available, they will be my go to marine engine. 3406 Caterpillars would be my next choice if space was available.
  14. Capt Ralph

    Capt Ralph Senior Member

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    A+
    Sad the 3406 never had a pancake option. :D:D
  15. cleanslate

    cleanslate Senior Member

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    Yeah what he said....I had 1962 GM 6v53Ns in my Matthews that did not leak cause I kept up on them, new gaskets where needed, and snug up nuts , bolts, and clamps twice a year. They ran at 180 F. at 2000 rpm..the blower did get oily.
    Now I have 471TIs...same thing no real leaks, just two small ones..:rolleyes:and I keep up on them too, snuging things up from time to time.
  16. Boomer

    Boomer Senior Member

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    Update...head and racks adjusted...exhaust (the heavy one) went on today...attaching all the watwr pipes and turbo in the nest few days
  17. Pamela005

    Pamela005 New Member

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    I am new to the DD, pair of 671 Ti on my boat. If there is a TO or TM with maintenance lists and 'must do' around or created I would like to get a copy. I have some of the DD manuals, but nothing for the shop mechanic. I have rebuilt engines so doing some work on the engines is in my capabilities, I am not that interested in pulling the heads or rebuilding the lower end on these engines, I will let someone with heavy special purpose gear do that. But gaskets and tightening I can do.
  18. Boomer

    Boomer Senior Member

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    Well..she ran good for a while and then started eating coolent....coolent on the oil now...thinking oil cooler failed
  19. Boomer

    Boomer Senior Member

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    Oil changes, impeller, belts, Engine zincs...that's a good start
  20. Capt Ralph

    Capt Ralph Senior Member

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    Head seals are a fowl.
    DD oil coolers are pretty solid. Yours may be external and easily checked but doubt it.
    Pull all side covers off and ensure no water in the lungs.

    Keep us up.
    Ship happens, even with the best of plans.