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  1. Re: Turbo Leak 671 TI

    Where 'ya see a busted ring? If you're talking about #5 that looks like lighting, but if there really is an empty groove that would be quite the feat - that's not a missing piece, its an ENTIRE RING missing. I doubt it as that sort of event usually leaves LOTS of evidence all over the piston skirt and I don't see any damage on the visible parts of it.

    As for the airboxes, yes, there's soot mixed with oil in there. But its not obstructing the ports; only one picture (the top one) shows material obstruction in the liner opening and its not enough for me to go tampering with it as it is not threatening to get into the cylinder or obstruct the ports. If the rings are not damaged and the engine runs ok I wouldn't change the kits and I DEFINITELY wouldn't try to clean the airboxes, which is almost GUARANTEED to get the gunk into the cylinders and do damage.

    Make sure the airbox drains are open and check the rings. As I noted the easiest way to do that is to bar the engine so the rings are visible in the port and press on them with a wooden dowel. They should have a "springy" feel to them. If you have one or more that have NO spring to them that ring is either missing a chunk somewhere in its circumference, its stuck (if its slightly proud to the piston) or its broken (if flush or below) and that cylinder kit is toast. In that case there IS damage to the bore whether you can see it without a boroscope or not and the engine must be torn down. The oil control rings cannot be inspected as they never come to the level of the port, but a damaged oil control ring usually shows up as grossly excessive oil consumption and/or lots of oil spitting out through the airbox drains.

    If you find one or more cylinders with one or more damaged rings then I concur that the kits need to be changed and due to contamination you probably need to do them all, rather than one as that will allow an airbox cleaning to be done as well - never mind that the labor to tear the engine down sufficiently to get one out makes doing them all not THAT much more work or expense. However, absent ring damage I wouldn't do it as the airbox, while dirty, isn't contaminated enough for me to tear the engine apart and replace the kits on that alone.

    This assumes the engine starts and runs ok. If I had a boroscope handy I'd look at cylinder crosshatch condition but absent one if it starts and runs ok and the rings check out I wouldn't tear the engine down from what I see in those pictures.

    That's my view on it; YMMV.
    http://www.denninger.net - Home page with blog links and more
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  2. #22

    Re: Turbo Leak 671 TI

    YMMV is the truth. I do not see a ring, but maybe it is the light. Assuming the ring is there you can see the soot blowing past it. Not good.


    Here is what happens in the real world with soot ingestion. IT IS SLOW DEATH. Forget the 30 second BS that is now, in 100 hr the kits will be trashed. The rings will be stuck and broken. Have seen it many times. Rings DO BREAK AND EXIT!!

    The die is cast. The soot made it to the rings, now they stick, then they keep getting blasted by the oily mung from the airboxes and they start to grind themselves to death. They start to smoke at start up then get hard to start, then they do not want to start without block heaters.....

    Yes it can be put back together and used but it will get worse and worse.
    I have a cust who had the same problem on his 671s and they still run, but do not try to start them without block heaters and even with the heaters, people think the boat is on fire!

  3. #23

    Re: Turbo Leak 671 TI

    That pic with the "missing ring" just looks to me like a normal 3 piece oil ring, I don't think the ring is missing. You can see the edges of the ring at the top and bottom of the groove. Of course, whether everything is sealing well is a different issue...

  4. Re: Turbo Leak 671 TI

    Capt, in a commercial boat I'd probably go do it, because its better to do it "on plan" than not, and when you're putting 500 or 1,000 hours a year (or more) on the motors having to do it mid-season is unacceptable.

    But in a recreational service vessel? No. Not now, IF the rings are ok.

    If the kits grind themselves over the next 2-3 years, they do. Why spend the money NOW? If they're running ok and starting ok, run the boat. Yes, there's a rebuild down the road, but it doesn't need to be done today by any means.

    Now if there's a busted ring in there, then you have no choice - the engine has to be torn down.

    When I had my 45 I used to be "Mr. Detroit" because I was known around the docks for having both the tools and knowing how to use 'em. I probably looked at a half-dozen boats with exhaust ingestion problems over that time, most of them with airboxes that looked FAR WORSE than this one.

    Every one of them the engine shops would recommend an immediate teardown and full rebuild. With those where I could get at the rings to look at them easily and found them not stuck or broke my view was the same - in recreational service if the ports on the liners are unobstructed and the engine starts and runs ok run the boat, knowing that you have likely taken a significant amount of life off the motors - but that the need to rebuild is not here today. Monitor for starting problems, performance problems and smoke that won't clear, especially after the engines are warm, and if you have easy access to the airboxes check 'em annually for stuck or broken rings. If you find ring problems tear the engine down, or if and when they are misbehaving in their operation. In the meantime run oil analysis on every oil change; if there is a SEVERE problem about to bite you in the ass you'll likely find it in the form of sky-high iron and chromium levels (chrome = rings, iron = cylinder kit walls among other things)

    Until then go fish.

    Of those half-dozen three owners took my view and two had rebuilds done. When I sold Gigabite the three who took my view were still cranking up to go fishing with no material change in their engine behavior a couple hundred engine hours and two or more years later but still had the $30,000 in their pocket, while the other guys had no material change in their engine behavior either but were light that same $30,000.

    For commercial guys the advice is different because the downtime can come fast and hard, the hours run annually are a LOT higher, and downtime hits revenue instead of enjoyment. There when you find trouble you fix it at the first reasonable economic opportunity, and winter is a good time to be doing that.
    Last edited by Genesis; 02-01-2009 at 04:49 PM.
    http://www.denninger.net - Home page with blog links and more
    http://market-ticker.org - The Market Ticker

  5. #25

    Re: Turbo Leak 671 TI

    Quote Originally Posted by MikeP View Post
    That pic with the "missing ring" just looks to me like a normal 3 piece oil ring, I don't think the ring is missing. You can see the edges of the ring at the top and bottom of the groove. Of course, whether everything is sealing well is a different issue...

    The oil rings stay below the ports.

  6. #26

    Re: Turbo Leak 671 TI

    Quote Originally Posted by Genesis View Post
    Capt, in a commercial boat I'd probably go do it, because its better to do it "on plan" than not, and when you're putting 500 or 1,000 hours a year (or more) on the motors having to do it mid-season is unacceptable.

    But in a recreational service vessel? No. Not now, IF the rings are ok.

    If the kits grind themselves over the next 2-3 years, they do. Why spend the money NOW? If they're running ok and starting ok, run the boat. Yes, there's a rebuild down the road, but it doesn't need to be done today by any means.

    Now if there's a busted ring in there, then you have no choice - the engine has to be torn down.

    When I had my 45 I used to be "Mr. Detroit" because I was known around the docks for having both the tools and knowing how to use 'em. I probably looked at a half-dozen boats with exhaust ingestion problems over that time, most of them with airboxes that looked FAR WORSE than this one.

    Every one of them the engine shops would recommend an immediate teardown and full rebuild. With those where I could get at the rings to look at them easily and found them not stuck or broke my view was the same - in recreational service if the ports on the liners are unobstructed and the engine starts and runs ok run the boat, knowing that you have likely taken a significant amount of life off the motors - but that the need to rebuild is not here today. Monitor for starting problems, performance problems and smoke that won't clear, especially after the engines are warm, and if you have easy access to the airboxes check 'em annually for stuck or broken rings. If you find ring problems tear the engine down, or if and when they are misbehaving in their operation. In the meantime run oil analysis on every oil change; if there is a SEVERE problem about to bite you in the ass you'll likely find it in the form of sky-high iron and chromium levels (chrome = rings, iron = cylinder kit walls among other things)

    Until then go fish.

    Of those half-dozen three owners took my view and two had rebuilds done. When I sold Gigabite the three who took my view were still cranking up to go fishing with no material change in their engine behavior a couple hundred engine hours and two or more years later but still had the $30,000 in their pocket, while the other guys had no material change in their engine behavior either but were light that same $30,000.

    For commercial guys the advice is different because the downtime can come fast and hard, the hours run annually are a LOT higher, and downtime hits revenue instead of enjoyment. There when you find trouble you fix it at the first reasonable economic opportunity, and winter is a good time to be doing that.



    That is fine, but you know it is coming. My point was that all is not going to be fine. But if you don't mind the smoke they will run for years like that.

  7. Re: Turbo Leak 671 TI

    Its always "coming" but most of the time in recreational service what ultimately "gets you" is something other than this, or if its this, its a long way down the road.

    Heh, we all have our viewpoints - they're kinda like butts and most of them stink
    http://www.denninger.net - Home page with blog links and more
    http://market-ticker.org - The Market Ticker

  8. #28

    Re: Turbo Leak 671 TI

    Looking at the pic blown up and with some added exposure, I can see narrow rings at the top and bottom of the groove, just like a 3 piece oil ring with a spacer in the center. However, if the oil ring groove is not in that location on a DD piston, I'd agree there is serious problem!

  9. Re: Turbo Leak 671 TI

    I want to see it up close - the oil rings on a Detroit do not come up to the level of the ports, and thus are not visible - that much is fact

    And yeah, if there's a MISSING ring, that's one of those "duh" sorts of things.
    http://www.denninger.net - Home page with blog links and more
    http://market-ticker.org - The Market Ticker

  10. #30

    Re: Turbo Leak 671 TI

    thanks for the all help guys!

    I'll roll that engine this weekend and get some more pics of the firing and compression rings on that cylinder for a better view. Currently, that engine does smoke on start up, clears in 2-4 minutes and stays clear running. It does run a bit warmer, however after seeing the air side of the intercooler that may be the explanation.

    john
    J Dickson

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