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No Repower - Rebuilding Mid-Season

Discussion in 'Technical Discussion' started by DOCKMASTER, Jul 10, 2015.

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  1. DOCKMASTER

    DOCKMASTER Senior Member

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    I had been seriously exploring repowering at the end of the season. Now it is not to be. At start of last trip, got up to cruising speed and within a few minutes Stbd engine shot to 100% load but RPM's were dropping. Shut her down immediatley and went below. Found coolant sprayed all over fwd bulkhead and overhead from being puked out the top of the recovery bottle. Got back to the dock and started troubleshooting. Coolant system would hold 10 psi when pressurized from expansion tank cap. However, starting engine even when cold and immediately start seeing gas bubbles coming out the overflow tube and system would build over 12 psi within 1 minute. We figured a cracked head, maybe head gasket (o-ring) or injector jacket. Isolated issue to outbd side and figured we could quickly do a couple of heads and get back on the water. Pulled turbo to make room and found turbo vanes on exhaust side chipped from what appears to be compression ring pieces going through. Although the issue of exhaust getting into coolant side is not related to turbo issue clearly I had additional problems.
    So after a few days to get past my initial ire and do some soul seraching I decided to scrap the repower idea and do a complete in frame overhaul of my starboard DD 12v92TA. This engine has never been completely overhauled and was pushing nearly 4,000 hrs. My port engine has less than 600 hrs so hopefully after doing the Stbd side I should be good for awhile. Yes, I know these engines are not known for their longevity but I take really good care of them, I don't push them hard and even if I can get 2,500 hrs out of them I'll be good for another 5+ years, maybe more. Further, I can get the engine rebuilt in about 3 weeks and still save the last 1/3 of this season. And lastly I can rebuild this engine for far less then what a set of new engines were quoted at and I don't have to cut the boat apart to do the swap.
    I'm still dissapointed though as I was looking forward to getting new iron and picking up a little speed. Oh well, I still love the boat and the Detriot's generally run well (other than issue above obviously) and push the boat and a respectable cruise in the mid-20 knot range. Pictures of the torn down block and parts on the shop floor as well as damaged turbo vanes IMG_1693.JPG :


    IMG_1691.JPG IMG_1692.JPG
  2. Capt J

    Capt J Senior Member

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    If you major them, you won't end up repowering for a long time. If you REALLY want to repower, I would just do it rather than major one. It's a tough decision but depends on what your wants are. Rebuild is quicker and cheaper. Repower is a faster boat and what you really want, so you lose part of the season.
  3. K1W1

    K1W1 Senior Member

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    He will probably keep the thick end of $100k by rebuilding vs repowering, that buys a lot of snacks to eat on the way there and back at a few knots less and bait for when you get there
  4. RER

    RER Senior Member

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    +1 ...more than $200k probably.
  5. Capt J

    Capt J Senior Member

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    It's true, it's much cheaper but he has been researching re-powering and talking about it for a while now and really wanted to re-power.
  6. Bamboo

    Bamboo Senior Member

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    Good luck. Nice to see others having 4K hours on a 92. Was there anything you can think of which may have prevented this failure?
  7. Capt Ralph

    Capt Ralph Senior Member

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    For day dreamers & inquiring minds, did you ever decide on a re-power package?
  8. Donzi 54

    Donzi 54 Member

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    Your decision will at least add more value to your engines resale. If and when you do the repower.
  9. DOCKMASTER

    DOCKMASTER Senior Member

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    Rebuilding this engine definitly puts off repower for foreseeable future. Rebuild will end up in the $75k + range. This includes replacing both blowers, both turbos, all heads, injectors, pistons,rods, liners, complete new raw water pump, new fresh water pump, oil coolers, etc. I also had to replace one exhaust manifold which the part was like $8k.

    Repower estimates were coming in close to the $400k range. Engines, gears, controls, bigger shafts, wheels and lots of labor. I might have been able to do the CAT C-18's and save $50k, maybe $75k. But I was planning to go with the MTU 10v-2000 (sorry Capt J :)) but it is moot now.

    I'm not sure if anything could have been done different to get more hours out of the engine. I've put about 600 hrs on it since I got it so hard to know how it was treated for the years before me. If I get another 4k hours I wouldn't be dissapointed.

    The engine is just about all back together now and they are hoping to light off later today or tomorrow latest.
  10. Capt Ralph

    Capt Ralph Senior Member

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    Any autopsy on what happened?

    Over revving thru the surf chasing trap raiders?
    Over pushing an iceberg out of the way and a floater blocked the water inlet just for a second or two?
    Ah, fighting and backing down hard on a trophy fish for 10 hours?

    Of course, it just didn't break down by itself..
    Or did it??

    Looking forward to good news tonight or tomorrow.
    Last edited: Jul 20, 2015
  11. DOCKMASTER

    DOCKMASTER Senior Member

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    Nope, she just gave all she had over 21 years. I only fish Salmon and Halibut so no chasing or backing down like you refer to :) #2 cylinder rings started coming apart. That sent little ring chips thru the turbos. We never spent the time to check heads or liners for crack as it didn't matter any more.
  12. Capt Ralph

    Capt Ralph Senior Member

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    Whoa
    21 years on same piston. Guess that is a good record. Bless it's heat.
    My excuses just sounded more fun.

    Of course when I have a failure,,,, It's never my fault. Those darn aliens were up to something again...
  13. karo1776

    karo1776 Senior Member

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    Dockmaster,
    Although, I am a little late to comment... you did the right thing. Considering your use of the boat in hours per year; satisfactory operation with the current set up in good condition; the condition of the other engine with break in hours basically; and; problems and expenses with re-powering. Best choice.

    The issue with the rings sounds to be combination of use and design of the basic engine. You are a light user with long periods of between use and long, many years of use, but good maintenance. The engines like to be run for long periods at power for best life... just not without maintenance and at high outputs. I think you just got some ring sticking from the accumulation of deposits, lack of lube and periods of non-operation. This conspired with the overall operational long term setting to result in this problem... bet it happened in startup or shortly after. At lease it was not catastrophic where re-power would have been you only real choice. Either the C18 or MTU v-10-2000 would not have faired better in the identical situation. The only question I have is what kind and what oil was used and how often changed was it over the life.
    See diesels like what is termed high ash oil but this is a misnomer because it refers to the anti-friction additive for prevention of cam and lift wear... what I think is critical in you use, particularly with Detriot 92's is what is called soot related viscosity increase and shear in diesel engines a description of potentially your ring failure cause... these in API are "C" rated oils. An intermittent use you might be better with a low ash oil. Of course manufacturer guidelines are important to consider.

    I just am thinking... here is the description for API website:

    "The “CI-4 PLUS” designation identifies oils formulated to provide a higher level of protection against soot-related viscosity increase and viscosity loss due to shear in diesel engines. When originally introduced, CI-4 PLUS identified CI-4 oils meeting a higher level of performance. CJ-4 oils include all CI-4 PLUS performance requirements. CI-4 PLUS appears in the lower portion of the API Service Symbol “Donut.” "
  14. Capt Ralph

    Capt Ralph Senior Member

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    Factory states CF-2 ONLY and single weight.
    The newer oils have newer ratings and updates in some areas, BUT DD still states CF-2, straight weight in their 2-strokes.
    Been using CF-2 in slow and fast boats. Oil samples are drawn often. Never a bad oil report.

    I'm not meaning to argue with your comments, these modern oils MAY be better, but it's hard to argue or change from factory standards.
    Don't think I've noticed a CH-4 or CI-4 in a single weight either.
  15. DOCKMASTER

    DOCKMASTER Senior Member

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    I use Chevron Delo 400 30 wt
  16. Capt Ralph

    Capt Ralph Senior Member

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    Seems the Delo 400 stright weight (if it is still rated API CF-2) may have less of this ash than the Delo 100.
    The Delo 100 is recommended for the 149s because of it's ash value (however it's counted). Both are considered good CF-2 oils around these parts.
    I do use a different brand, not because of issues, just a better $ deal.
    In the cold waters up thar, 30 wt may be perfect. In Florida, 40 wt.
  17. karo1776

    karo1776 Senior Member

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    Good thing I don't go to bed very early...
    Read the Delo400 data sheet...
    "Delo 400 monograde oils are not recommended for use in DDC two-stroke engines."

    https://cglapps.chevron.com/msdspds/PDSDetailPage.aspx?docDataId=77118&docFormat=PDF

    rcrapps... I was not specifically referring to the particular grade but just the generality of "C" grade oils... happened to grab the API statement on the CI-4+ oil.

    Now the why... it is the two stroke Detroit's rings are directly exposed to the ports. Something that does not happen in a 4 stroke.
  18. DOCKMASTER

    DOCKMASTER Senior Member

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    Sorry, my bad. We use Delo 100 40 wt
  19. karo1776

    karo1776 Senior Member

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    Now I really do not think it was the lack of ash... rating in this case: As would be the case in a run all the time engine in commercial use.

    I think your issue is the viscosity issue... not the ash value.... which simply means the additive for the sliding friction burns and leave an ash... the more modern oils leave little ash but the additives are more expensive.

    In your use of low hours per year... set around a lot... long time between constant running and off. What happens is the oil around the rings basically gets thicker... gums up if you will... and is less lubricative. I would never suggest a 40 wt in your application and 30 wt is likely not a good choice either. I would use the Delo 400+ 15-40w or the newer semisynthetic version or the LE version.
  20. karo1776

    karo1776 Senior Member

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    I wrote that post before you did the post on using 40 wt.