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  1. #1

    Default "I have a newly remanufactured

    "I have a newly remanufactured Perkins 6.354 which has a persistent knock or vibration at all speeds, since engine was installed.
    The builder swears it cannot be mechanical; but I can't get to the bottom of it.

    The injectors have been removed and checked, twice.

    Breaking fuel connections at the injectors does not indicate any cylinder is running any differently from any of the others.

    Knock/vibration is NOT cylinder-specific, it is the same regardless which cylinder is off-line.

    vibration is more severe under load.

    NOT related to transmission or drive train; even with the transmission physically disconnected the knock/vibration persists.

    Any suggestions would be appreciated, thanks."

  2. #2
    pedlyr's Avatar
    pedlyr Guest

    Default Flex coupling/ vibration dampe

    Flex coupling/ vibration damper OK?

  3. #3

    Default "As far as I can tell, without

    "As far as I can tell, without pulling the bell housing.

    there's some indication at idle that #6 is working a little harder than the others... couldn't find it before. If so could it be fuel pump?"

  4. #4
    pedlyr's Avatar
    pedlyr Guest

    Default "Bill- Did you disconnect t


    Did you disconnect the gear (tranny) from the engine? If so, you should have been able to investigate the coupling.

    Try cutting out the cylinders to find a weak one(s). With the engine running, crack (not loosen entirely)the nut at the injector tip for each cylinder one at a time. You will stop that respective cylinder from firing. You will be able to hear it. If not, then that cylinder wasn't firing before hand. Carefull here, if you make a mess you are doing it right.

    Usually cylinders don't work harder than others, but they can work less or not at all."

  5. #5

    Default "The installation has a Warner

    "The installation has a Warner Angle drive between the engine and the transmission, I removed the U joints in the drive leaving only the adapter to the drive. However the case is still in place. I could find nothing wrong or loose but I'm planning on checking it again tomorrow.

    Engine has a "lope" at slow idle. Breaking the injectors, #6 has MORE of an impact than the others. All 6 ARE firing. I'm going to swap that injector to a different cylinder and see if that makes any difference."

  6. #6

    Default "That's a WALKER angle dri

    "That's a WALKER angle drive, if it matters. Anyway I had the cover off again and I can see the drive adapter is bolted to a steel disk about 10" in diameter, which in turn is bolted to the what I think is the flywheel with rubber mounts, so I'm guessing this disk is the vibration damper. Anyway everything is tight and I can see nothing amiss.

    Switched the #6 injector with #1, the alternate cylinder. Can't see a whole lot of difference, yet. That particular injector (now in #1) is a replacement injector and has less time on it than the others. Don't know if this would make a difference or not."

  7. #7
    pedlyr's Avatar
    pedlyr Guest

    Default "Bill- I would try to make


    I would try to make sure your drive train is OK and that your problem is engine related. You never mentioned smoke, which is usually present for engine problems. Especially with bad injector tips.

    If you have a lope or roll at idle, make sure your fuel system is clean and functioning. Those Perkins bowl style fuel filters can leak or suck air easily. Check air inlets, turbo's and aftercoolers (which I don't think you have).

    Start with the easy things first. Eventually you may need to get a pro to look at things if you are unsuccessful, but at least you can rule allot of things out.//Ed"

  8. #8

    Default "Drive train is good. Prop ju

    "Drive train is good. Prop just repitched/reconditioned. new shaft and it's straight. Strut is tight. Relatively new Cutless. Alignment good. I don't see any wobble or vibration at the stuffing box. Don't know what else to check there. Anyway, the vibration/knock persists in neutral.

    I had a LOT of blue smoke at first, but replacing a bad injector and advancing the injection timing took care of that. No appreciable smoke at any speed now. No detectable lube oil consumption either. No turbo or aftercooler to worry about. Injector tips are clean. Fuel system is clean and tight as far as I can tell; just changed the primary filter and re-primed and bled everything. No noticeable difference. I'll check the engine filter, but the way the fuel system is set up it looks like it's under positive pressure from the fuel pump; and excess goes back to the tank. So even if there's a leak it SHOULDN'T suck air. At least I don't think so.

    Didn't start the engine today, but plan to go through all the injectors and check RPM with a laser tach; and record what the drop is for each cylinder. That should tell me something. What, I'm not sure.

    Already have an appointment with a diesel mechanic for next week to go for a ride and listen to the engine. I've been battling this beast for six months and it has me stumped."

  9. #9
    Join Date
    Feb 2006
    St. Thomas, U.S. Virgin Islands,

    Default "Kind of sounds like you have

    "Kind of sounds like you have something serious. Depends on the frequency and type of knock.

    Rapid sharp metallic knock usually means rod-piston-combustion issues.

    Dull knocking in sync with RPM 1 per rotation usually means main bearing issues. I have heard these engines do both.

    Since it is a newly "rebuilt" engine you have a host of variables to deal with. If you can not get it to go away by shorting the cylinder, and I mean you have to dump the fuel hard at the connection, then you probably have main bearing issues. Opening the engine up will tell the tale.

    Good luck."

  10. #10

    Default "I've done several recordi

    "I've done several recordings and they seem to indicate the knock is every other revolution; at 500 rpm I get about 4 knocks per second according to the computer. That about 240 knocks per minute.
    At 1400 rpm it's still every other revolution, but heavy enough I can FEEL it with the hatches closed.

    I broke all 6 injectors and measured the RPM with a digital laser tach:
    Base RPM: 500
    #1 off : 468
    #2 off : 461
    #3 off : 448
    #4 off : 478
    #5 off : 454
    #6 off : 454

    The knock SEEMS like it's coming from #5, but hard to tell."

  11. #11
    Join Date
    Feb 2006
    St. Thomas, U.S. Virgin Islands,

    Default "Your knock is consistent with

    "Your knock is consistent with the firing of the cylinder. One of the injectors in the vicinity of the No. 5 cylinder has to be bad. I would replace them all to be sure, and later you can send the ones you removed for testing and recertification as spares. Unless the injector pump is bad, you're running out of stuff to check. Double check the injector pump timing as well. The engine shouldn't lope.


  12. #12

    Default "thanks I've been looking

    "thanks I've been looking into that. I mixed up the injectors and the sound changed somewhat; but I still had the lope and it still seemed to be coming from the vicinity of #5. I've sent the injector pump in for rebuilding/or replacement (warranty) and we'll see what that does. All injectors "test" ok, but if this doesn't do it I'm going to have them all rebuilt anyway so hopefully they'll at least be the same. I don't think NEW injectors are available for this old engine."

  13. #13

    Default "I installed a rebuilt injecto

    "I installed a rebuilt injector pump and it seems to have solved 90% of the problem. What remains is probably slight differences in the injectors... Thanks everyone, for your help."

  14. #14

    Default I'm having all the injecto

    I'm having all the injectors rebuilt hoping it'll take care of the rest of the vibration.

  15. #15
    chandu's Avatar
    chandu Guest

    Default "HI, I have sulzer Engine of

    I have sulzer Engine of 16ZA40S,in which as per running hour we are changing its mechanical torsional vibration damper,during the supply of this damper from Geislinger its inside hole dia which will hold to Cranshaft was undersize by 2 mm ,which we will machine at site as per the drawing.But i would like to know wheteher it needs dynamic balancing of damper before the fittment or else let me know hat tests will be carried out on damper before the supply,Pls anybody can answer my queries i will be great ful.


  16. #16
    Pat Patterson's Avatar
    Pat Patterson Guest

    Default "I'm so grateful to have r

    "I'm so grateful to have read all of this; it has convinced me that a rebuilt is not the way to go. But, I need a replacement for my Westerbeke 42B-4. Salt water entered the cylinders and #4 has a great ridge in the wall. I went to Diesel school and tore it down and the instructor says we can fix it and it will probably run OK long enough to sell the boat, but that's not my style. I have spent almost six hours trying to find something to replace the old engine without success. Anyone any thoughts? I'd appreciate them"

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