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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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    RC,
    I clean the k&n airseps every year with k&n filter cleaner. Remove spray down with hose removing whatever and then re spray with oil.
    Thx, Skip
  2. Capt J

    Capt J Senior Member

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    The station wagon effect definately has a lot to do with it. I ran a 62' Sunseeker to Bimini and back yesterday, 105 NM's, it has exhaust on the side of the hull and we do get some soot behind the exhaust a few feet aft of it. I also ran 2 58' searays with MAN 900's long distances Ft. Laud- CT, and DE to Ohio and there was no sooting and no visible soot or exhaust trail when running. However, injectors are supposed to be yanked and checked at the 1000 hour service, did they do that? But, if they run clean without the tender I wouldn't be alarmed.
  3. CSkipR

    CSkipR Member

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    Capt J,
    I will have to check my records when I get home on the 1000 hr service but I do not think they were pulled and checked.
    Thx, Skip
  4. Capt Ralph

    Capt Ralph Senior Member

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    From the CRM manual;

    Caution:
    Checking the injectors of Common
    Rail engines is not specified.


    I don't agree with this. I usually prefer all injectors get pulled and popped, not replaced unless there is a problem. Pump pressures should be checked if possible IMO.

    Your tech (who we know) would of gone by this (thin) book. Visual inspections, all fluid changes, test run for errors (Including vibration analysis) satisfying the alignment check and maybe hose checks. This would satisify the manual.

    Intercooler and air service IS a bit thin acourding to the manual also.

    I can send you a copy.

    ,rc
  5. Capt J

    Capt J Senior Member

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    On common rails you can do a cylinder drop out test with the computer and verify function pretty well, without necessitating pulling them. However, if you do have to pull one and it's been in there several thousand hours, it might not come out without a lot of heartache, however, having individual cylinder heads does make it not too terrible.

    The Man 1100 common rail manual (service interval) I have states doing all of the coolers and after coolers every 2 years or 1000 hours.
  6. Capt Ralph

    Capt Ralph Senior Member

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    Not by hour, just every two years;

    A1 Changing
    D Both valve caps on expansion
    tank
    Cleaning
    D Intercooler / charge-air pipes /
    turbocharger
    D Heat exchanger (pipe cluster)


    Still a thin statement per the manual. Charge air data from the computer and display will tell you if something is amiss,,,

    I'm still convinced all is well and you were putting a load on.

    How was your fuel consumption vs this ride before? I'm sure it was close plus the wind/mpg on you.

    ,rc
    Last edited: Jun 28, 2015
  7. CSkipR

    CSkipR Member

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    RC

    RC,
    I'm sure the injectors were not pulled on the 1000 hr we had done 2 yrs ago 200 hrs ago. Don't believe it is on the 1000 hr service. Valves adj, belts, heat exchanger and intercooler pulled and cleaned, caps replaced. Sent email to Man rep (you know) and he is recommending removing the waste-gates checking them for seating and sticking before pulling injectors. Your thoughts on this? If you can send me a copy.
    Fuel burn coming over was just slightly higher than norm. There is only a charge air temp on the gauges not sure whether that would help identify issue. Also a pressure after air filter if that helps.
    Thx, Skip
  8. CaptPKilbride

    CaptPKilbride Senior Member

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    89% at 1900 rpms is indeed a very high load factor. CskipR what is the load factor at 1900 RPM when the boat is configured to be able to turn up to 2360 RPM?

    I think you are lugging these engines when towing that load. The cylinders are being overfueled and that is what is causing the soot.

    Oh, and the computer diagnostic that does the cylinder cut out test, and compression test, could very well not catch a problem that a proper survey with pulling injectors to be sent out for testing, and put a proper compression test guage on each cylinder. Not a bad idea to bore scope each hole as well.
  9. CSkipR

    CSkipR Member

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    1
    Currently the boat turns up to 2360 rpm although when I was fully loaded & towing I didn't try to run it up to max rpm. The normal load factor is between 75-77 when running at 1900rpm.
  10. Capt J

    Capt J Senior Member

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    I still think everythings fine and you just were overloaded.
  11. CSkipR

    CSkipR Member

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    Okay just ran the boat without the tender and here are my readings on sync. Everything on the gauges is in green.
    sb - 1893rpm load 76% charge air temp 104 boost pressure 22 speed 25.6knts
    port - 1900rpm load75% charge air temp 102 boost pressure 23

    Going to tow tender back to Fl this week so will record those as well. Should be less load as not near the gear we had before.
  12. CaptPKilbride

    CaptPKilbride Senior Member

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    If your normal operation without the tender allows the motors to turn up to 2360, and the % load at 1900 RPM is 75%-76%, then you change to towing a tender and your % load at the same 1900 RPM has now jumped to 89%, you are operating in fuel overload. What were your exhaust gas temperatures?

    In any case, operating those engines with such a scenario where they are unable to turn up to their rated RPM is causing damage.
  13. CSkipR

    CSkipR Member

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    Really don't understand your post. The engines are turning up to the correct rpm (2350) with clean bottom and no tender. When I'm towing the tender the load jumps up to the high 80s at 1900 rpm and speed drops to 21-22 knts. Assume you are saying the engines could be damaged because they may not reach their maximum rpm with the tender. Whether they will or not I'm not going to try to reach those rpms towing the tender.
    My post was more directed to the amount of soot I had on the trip over here to the Bahamas towing the tender. Going to have the waste gate valves checked when I return. He suggested they maybe stuck open and that will cause sooting.
  14. CaptPKilbride

    CaptPKilbride Senior Member

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    I apologize for not being able to explain why your engines are in overload when towing the tender. Would be easy to explain face to face with a pen and paper.

    When you are not towing, you are able to turn up to the rated RPM. 2360 RPM = 100% load. And in this same condition, at 1900 RPM you have about 75% load.

    Now, add a heavy load and towing the tender. I would be astonished if you were able to get them to turn up to 2360 RPM. My guess is you will probably only get in the neighborhood of 2075 - 2100 RPM at WOT. So, what is happening is the fuel system has to put a lot more fuel per cycle into the cylinder when you are at 1900 RPM and 89% load. I have heard this called "lugging" or "overfueling", but whatever it is called it is shortening the life of your engines. I believe the soot is from overfueling.

    What was the boost pressure when you were running at 1900 RPM and 89% load when towing?
  15. CSkipR

    CSkipR Member

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    No problem that was a good explanation. Unfortunately I didn't record any of the information towing the vessel. On the way back to Fl this week towing the tender I will record the numbers. Will post later. Thanks
  16. Capt J

    Capt J Senior Member

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    I agree with CaptPkilbride, but at the same token doing it once a year might not shorten their life that much. I would also try 1950 with the tender as it might get more momentum going and both boats fully on plane and load factor might drop. If it doesn't put the trim tabs down and back down to 1850 and see where load ends up.

    What CaptP is trying to say is with the heavier load, the boat is now overpropped (in that situation towing the tender) so it's like being on a bicycle and peddling in one gear too high for your speed, takes more effort or too much effort yet you're still travelling at the same speed over ground.
  17. CSkipR

    CSkipR Member

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    Capt J & Capt Pkilbride
    Back from the Bahamas with my update. Left GT with full fuel & water & lots of misc and towing the 19ft tender heading to Ft. Pierce. Changed racors before leaving. Capt J as you suggested I increased the rpm up to 1950 for the first 30nm before having to slow down because of the weather. Here were results. Lots of black smoke coming up to cruise, but the load factor was definitely better.

    Port 1947 rpm - boost pres 25 - load 82 - charge air temp 100
    Starboard 1946 rpm - boost pres 26 - load 80 - charge air temp 97

    We did some chugging at 1000 rpm for about two hours. Then back to running around 1850 because of seas & weather. The results were definitely better than the trip across. The transom, cockpit and helm definitely had less soot. I think I'm going to have the waste gate valves checked to be sure they are properly working and not stuck open. I welcome your thoughts and thanks for the discussion.
  18. Capt J

    Capt J Senior Member

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    Wastegates are fine...... 25/26 lbs of boost is what you should be seeing....You're just heavy with the tender....why come back with full water?
  19. Capt Ralph

    Capt Ralph Senior Member

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    I thought about that also,, unless it's needed for trim. Where is the water tank on this boat?
  20. Capt J

    Capt J Senior Member

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