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Detroit diesel 12v71TI no power out of the hole

Discussion in 'Engines' started by CaptOz, Jun 5, 2014.

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  1. CaptOz

    CaptOz Member

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    Hi,


    I want to share with you the observations I have been seeing after I went into the water from the 60 days on the hard at Cay Marine.

    Changes from before the yard are as follows:
    1. Brand new bottom with no bumps or growth.
    2. 3 bladed Props now instead of the 4.
    3 . Side Exhaust now instead of the straight back.

    The initial sea trial was great. Boat planned ok .. a little longer than with 4 blades but not much more. Economy was way up. Burned the fewest total to Bimini ever. On that trip I had some clamps give on the starboard engine. 2 where on the water side of an air cooler and 2 where on the water outlet of the fuel cooler. The prior was causing water to spray right at the airsep of the port engine which caused salt to get into the turbo. The latter was just causing water to leak into engine room.

    After this situation happened, I notice 2 days later when coming back from Bahamas that boat was having a harder time planning. I thought it was perhaps the airsep that had gotten clogged on the port and this was reducing the ports power. When I got back to the dock and checked it a few days latter the Turbo on the inside bank of the port was stuck. I sprayed pb blaster on it and was able to unstick it and left it spinning freely.

    I then ran boat a couple of more times the hard to plane problem was still there. What I noticed on the rpm gauges is both motors spin easy up to 1200 rpms, the port continues to climb and puts out black smoke when I am trying to push it. The starboard does not. I move it to WOT and its almost like RPMS(starboard) drop momentarily. There is minimal black smoke coming out of the starboard. Eventually when Port Engine reaches 1650, the boat starts to plane, and at this time that's when the Starboard engine RPM begins to rise beyond 1250 rpms. Eventually the Starboard meets the Port and boat is doing 22knots at 1850 with ease. There is a light trace of black smoke from the starboard but nothing more than before. Fuel was relatively clean, but bowls has some black algae so I cleaned them after the trip but saw not difference.

    When I got back from Memorial day I had extensive fuel contamination problem. I bought bad fuel in between Island trips. I then fixed this for the Charter this past weekend and did not affect the problem at all. Boat took the longest time to get on plane leaving the Yacht Club(4-5 mins). Also, now I am starting to see significantly more black smoke at cruise out of the Starboard Engine.


    Turbo on the starboard spin freely and are relatively new.. Less than 300 hrs or about 1.5 years old. Air boxes were done about 2 years ago on that engine.

    We don't know how many hours that engine has, but the last oil sample said it was worse than the port. Yet, the starboard clearly had more life before this problem.

    Another important note on fuel consumption. Out of the hole with both engines at WOT, port reads 44gph and starboard reads 15gph. Then at cruise at 1850 Port reads 35 gph and Starboard 38. Starboard is about 20% higher than it usually was.

    What do you guys think?

    It seems like either fuel is not getting there when it needs it, or perhaps some injectors are shot.

    Thoughts?
  2. HIBANX

    HIBANX Member

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    You stated that you had a fuel contamination problem at some point and that you remedied it. I assume you replaced the fuel filters, both primaries and secondaries. I have seen Racor filter housings become clogged with algae in the center where the little ball seats. I would suggest getting a rebuild kit and tearing down the filter housings. If all turbos are spinning freely on both engines and the bottom and running gear are clean, the problem is most likely fuel supply or a bad injector.
  3. RER

    RER Senior Member

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    In my experience once a turbo gets stuck they are done. Unsticking it can get you by long enough to finish a trip or whatever but ultimately they are never the same.
  4. CaptOz

    CaptOz Member

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    Turbo is on the port side which is engine that is running fine.

    It is still spinning freely .

    The problem was there before fuel contamination. So I actually took apart racor a twice and on the second go around I replace secondary filters as well.

    One thing I found last night that I forgot to mention was that the air stop flaps on the bad engine were not 100% open. I would say it was 90% only.

    I will run boat tomorrow and report findings.


    Thanks
  5. RER

    RER Senior Member

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    ...oops, yeah I think you might be on the right track there. I would still suggest that breaking loose a stuck turbo is stopgap.
  6. CaptOz

    CaptOz Member

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    The port engine is running fine. I agree turbo getting stuck is a potential problem but has nothing to do with Starboard engine not going past 1200 rpm under load.
  7. Capt Ralph

    Capt Ralph Senior Member

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    You have to realize that the compressor wheel spinning freely by finger does not mean much. The extreme high rpm they spin is from another world and can not tolerate even a salt stain on a rotor surface.
    With that, one of your turbos still may not be spinning up to speed.

    Your just starting to compress some good air around 1200 rpm.

    Your air filter may be clogged with salt. Walker's cleaner may not get it all out of the media. Secure your engine room run them at load a bit without the filters.

    Salt in the inter coolers? In the air box?? Injector tip inspection time...

    And real life for me; a dry riser from the exhaust log to my turbo had cracked. Releasing some expanding gasses. Turbo not getting full pressure from the engine. Black smoke out the back and great loss of rpm.
    Interestingly enough, engine room did not fill up with black smoke.

    71's rule,

    rc
  8. CaptOz

    CaptOz Member

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    I cleaned all air filters and inspected Air Box of the turbo that got salt into it. It looked good.

    As far as your situation, the black smoke from your riser leak simply gets sucked back into the engine, I would expect minimal smoke in the engine room at cruise.
  9. rgsuspsa

    rgsuspsa Member

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    CaptOz: As turbo boost pressure increases it can and will deflect the air shut down flaps toward the closed position, if they are not fully retracted when the engine is not running. This matter must be corrected.
  10. CaptOz

    CaptOz Member

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    Thanks Ron...

    I will know later today when I try to run her...
  11. Capt J

    Capt J Senior Member

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    If you ingested saltwater into the airsep, I would think the Turbo has been seriously effected or worse a cylinder. I would recommend putting boost gauges (mechanical) on both motors as well as fuel pressure and running it and seeing what you get. Having too much propellor pitch will also cause the boat to act as you describe. Generally when going to 4 blades you use 1-2" less pitch.
  12. Jimbo1959

    Jimbo1959 Member

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    I second the mechanical gauges. This will tell you right away whats happening.
  13. CaptOz

    CaptOz Member

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    Engine that ingested salt water through airsep is the port side. Engine that is not responding is the Starboard side.

    I ran the boat a over the weekend and Problem with the starboard engine is still there. A very slight improvement was seen but still taking too long to get on plane. Starboard Engine RPMS just don't show up till the ports gets the boat on plane. Also fuel consumption on the Starboard is up 20% according to Flowscan.

    Where do I place the tap for the boost Gauges? Would that be at the Blower? Or at the Air Boxes?

    What should the boost pressure be ?

    And What should the Fuel Pressure be?

    Thanks!
  14. Jimbo1959

    Jimbo1959 Member

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    You can take the airbox drain out and go in there 1/4 npt. As to fuel psi it should be around 50-70 psi at 1500 rpm.
  15. CaptOz

    CaptOz Member

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    Is the Fuel Pressure reading at idle at 1500 or under load?

    Thanks Jimbo!

    Ozzy
  16. K1W1

    K1W1 Senior Member

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    Hi,

    Does your engine get to this pressure at either state?

    50-70 PSI at 1500 rpm underway will be a much better indicator of the pumps state than the same at no load.
  17. CaptOz

    CaptOz Member

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    I have not tested yet. Will report back tonight.

    Thanks
  18. CaptOz

    CaptOz Member

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    Didn't connect Fuel Gauge yet, however yesterday I ran both engines at WOT at the dock.

    Port : 2668 RPMS
    Starboard: 2442 RPMS

    Also, I have a Glendenning Synchronizer in which the PORT is the Master and Starboard is the slave.

    Also I verified that Throttle linkage has full travel.

    Since Starboard has ~200 rpms less, can this mean not enough fuel? Or perhaps a broken injector tip?

    I checked the water for Fuel Sheen and saw nothing.

    Thanks!
  19. K1W1

    K1W1 Senior Member

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    Hi,

    You will answer your own question when you determine the fuel pressure.

    A split nozzle would likely knock off more than 200 rpm.

    What is the condition of your fuel filters?

    When underway at WOT can you see if there is a different vacuum on each side?

    Less vacuum on the "slow side" compared to the other engine at same RPM could be an indication of pump inefficiency.

    These things use a simple gear pump to push the fuel to the injectors, if you have a spare swap it out and see if things improve
  20. CaptOz

    CaptOz Member

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    Fuel Filters, Primary and Secondary are all new. Racor bowls were cleaned and free of dead algae. Fuel in Bowl is crystal Clear.

    Have not looked at the Vacuum pressure on my Racor Gauges. Will keep this in mind.

    I don't have a spare pump. If its gear driven, how can it operate partially?