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Man CR900 valves & injectors

Discussion in 'Cabo Yacht' started by CSkipR, Jun 26, 2015.

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  1. CSkipR

    CSkipR Member

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    Had a lot of soot this trip over to the Bahamas from both engines. We towed (cruise speed of approx. 21knts) the 19ft tender and were loaded down with gear for two months upon arrival at Green Turtle there was soot all over bridge, cockpit, instruments, transom, etc. Had just changed all racors and internal fuel filters before leaving Ponce.
    Going to have the engines looked at when we get back to Ft. Pierce. Called Man (Ace Marine) and they said they would check the valves first (they were adjusted on the 1000hr service) and motors currently have 1100 hrs so short period. Next he said they would check injectors. Anyone have a rough idea what the injectors run for the common rails if they have to be replaced?
    Thanks, Skip
  2. Capt J

    Capt J Senior Member

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    Not off of the top of my head.

    What rpm's were you running over there at? It's probably mostly from being overloaded (weight and tender towing). I wouldn't think the valves would be out of wack 100 hours later, if they were adjusted properly.
  3. CSkipR

    CSkipR Member

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    Anywhere from 1750-1900rpm. I agree on the valves hard to believe they are the issue. Much more likely the injectors. These engines have always smoked slightly more than most common rails I have been on.
  4. K1W1

    K1W1 Senior Member

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    It could be any number of things. An Exhaust leak could be restricting the air filters, do you run your blowers underway? Poor quality fuel?
  5. CSkipR

    CSkipR Member

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    Possible but unlikely since its both engines. I have tried running both ways running with blowers on and off. Mostly off. Owned boat for 7 years.
  6. Bill106

    Bill106 Senior Member

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    AN exhaust leak can easily clog both engines intake filters but I'd bet it was simply a matter of overloading. Even though you were at normal cruise RPM's with the tender and extra supplies they were working much harder than normal and using more fuel to maintain those turns. Add in a following wind and you'll get soot everywhere. Do her displays show load%, and if so how much above normal was it?

    I've towed a few over and always had more soot on the transom, both mechanical and electronic controlled engines.
  7. CSkipR

    CSkipR Member

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    Bill,
    My normal load % is around 75-76% and this trip it was in the high 80s. We did not have a following wind actually a head wind. The boat has always had a station wagon affect that certainly doesn't help this issue. Since 05 was the first year of the common rail Man maybe they are just not as finely tuned as the new ones.
    If it was an exhaust leak wouldn't I smell exhaust in the engine room?
    Thx, Skip
  8. CSkipR

    CSkipR Member

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    K1W1,
    I did run over this trip (approx. 15hrs) using the blowers if that could have created this issue.
    Thx, Skip
  9. Capt Ralph

    Capt Ralph Senior Member

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    Lots of swells? Running uphill will really put a load on. Was the tow timed with the ships swells or fighting (drogue) against you?
  10. olderboater

    olderboater Senior Member

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    Just a point here, using 88% and 75%, you were 17% above your normal load. That is a pretty significant amount.
  11. Capt J

    Capt J Senior Member

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    I agree, I don't think you have an engine issue, you were simply overloaded. 89% at 1900rpms or less is quite a high load factor. Did you put the trim tabs down to see if that helped load and speed? If you plan on towing this boat often, I'd recommend taking 1-2" pitch out of the props and running a higher cruise rpm and keeping load at 75-80% (when not towing) and a lower cruise rpm with load around the same when towing. What rpm's do you make at full throttle, boat full fuel and water, not towing anything?
  12. CSkipR

    CSkipR Member

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    Capt J,
    With clean bottom and props it turns 2360 rpms. When I got the boat in 08 the props were 4 blade 28x40 and the load was high with full fuel and water and could not turn up to 2350. Had the props tuned and pitch reduced to 37.5 and since then been able to turn up to 2360rpm.
    Did run with the trim tabs partially down as this boat rides bow high normally although we had a lot of cases of water, beer, etc up front. Many of the 43 Cabos have the R800 6 cyc and have a lot less weight in stern of boat. Also all 700 gals of fuel are under cockpit floor.
    I only tow the boat once a year when we go to the Bahamas. That's a total of approx. 30 hrs there and back.
    Changed racor fuel filters (10 micron) when we got here and they were changed before we left.

    RC,
    They were not swells it was a sloppy mixed sea out of the east.
  13. Sea Gull

    Sea Gull Member

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    My last boat had the same engines. We always saw more smoke (and resulting transom soot) when we ran higher loads. Our normal was 80% load as shown by the engine controls with almost no soot. On days we saw 90% due to swells, we got soot.
  14. CSkipR

    CSkipR Member

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    SeaGull
    Thanks for the info. Just curious what kind of boat you had that ran that high 80% at normal cruise. This boat has a deep vee from bow to stern and weighs about 48k pounds.
  15. Sea Gull

    Sea Gull Member

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    Sea Ray 58 Sedan Bridge. 51000 pounds dry with a cruising weight of just over 60,000 pounds. We were turning 30x33 4 blade pops. At WOT we were at 2350 and 100% load. At 80% load we were running 2000 RPM with a cruise speed of 26 knots.
  16. CSkipR

    CSkipR Member

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    Did you have the oil cooler gaskets replaced on both engines? Had to do that around 400 hrs and everyone I have ever talked to with those engines had to have this done.
    So you were running most of the time at 2000rpm or 80% load. I have not run at 2000 very much because I thought that might be too hard on the engines. At 1900 running about 26 knts.
  17. Capt J

    Capt J Senior Member

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    Skip. With the fact that your engines turn up rpm's, I think everything on them is fine and you were just overloaded on your trip and would leave everything well enough alone considering you only tow the tender once a year....... MAN recommends running them at 80% load, of course if you don't feel comfortable doing that 75% load won't hurt anything either.
  18. Sea Gull

    Sea Gull Member

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    Skip, oil cooler gaskets were done somewhere around 400 hours ( can't recall exactly). When I traded her in, the dealer was going to re-do them at about 800 hours, just to be on the safe side. I considered it a permanent fix, but better safe than sorry.

    Our use of that boat over the 8 years we owned her averaged to just about 100 engine hours per year. I don't think 80 or 85% load changed the life of those engines in any way. If I put 500 hours per year on them, I might think differently.
  19. CSkipR

    CSkipR Member

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    Capt J,
    Thanks for the suggestion and believe me I'm not looking to spend money although certainly don't want to damage the engines. Ironically yesterday I talked to two boat owners over here that have the same Man CR900 engines. One a 58 SeaRay like Sea Gull owned and the other a Viking 45 both about same years. Neither one smoke or produce soot according to their owners although they were not towing. I will wait for awhile after we get back and see how the engines do. My engines have always produced some soot even on a day trip the transom needs to be cleaned well. Maybe a lot of that is the station wagon effect that we have on this boat.
    No one has ever told me 80% load is where they should be run. Always thought that was too high and you should try to keep below. Great to know.
    Do you recommend any injector cleaner or are most just bs?

    Sea Gull,
    That's about the same hours we put on our engines a year. Appreciate your feedback and to learn running 80% load is fine. Will see how the engines perform after we get home and do some local trips.


    Thanks, Skip
  20. Capt Ralph

    Capt Ralph Senior Member

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    I'm hoping your air filters were changed during the 1000 hour service and inspected since.
    I remember replacing the air filters on one ship with 900s. They looked like brand new filters till they were beat on the dock and tons of stuff came out.