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Thread: diesel knock with elsbett nozzles

  1. #1
    Join Date
    Jul 2008
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    Nelson Bay & Sydney
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    diesel knock with elsbett nozzles

    Looking for help from the forum.

    I recently fitted some elsbett injector nozzles and the engine now knocks. It has never knocked before. I fitted the new nozzles with the aim of reducing gumming problems.

    The nozzles were fitted a week ago and set at 165 bar. The previous denso nozzles were set at 160. As soon as the engine was started on diesel there was a slight knock. After switching to veg the knock increases. I have driven 2500 km since and little has changed except that there is almost no knocking on diesel and the knocking on veg still seems the same. After the first 100 km I added some petrol to the veg tank to make a 5% mix which made no difference to the knocking. It's back to 100% veg now and the symptoms are almost the same as a week ago.

    The van smokes at idle on veg for the first time. The smoke is white.

    I'm unsure what to do...

    One option is to put the old injectors back in, but I would prefer to get the elsbett nozzles working in the hope of having no more gumming.

    So,

    What's causing this and what can I do about it?

    Any help in understanding or fixing this proplem would be much appreciated.

    Thanks
    Last edited by 03Hiace; 24th June 2009 at 10:28 PM.

  2. #2
    Join Date
    Apr 2006
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    New Zealand
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    Re: diesel knock with elsbett nozzles

    Do the elsbett nozzles look any different? Any longer than standard?
    Is the knock you refer to known as "diesel knock"? Is that the kind of knock it is?
    I've had diesel knock when the nozzles carbon up badly, but yours doesnt seem like it could be that if it knocked immediately...& on diesel?
    It looks like you may have to refit the originals and compare results.
    Also carefully check nozzles for build up and also the hole where it seats.
    It's a chore I know. I got it down to 35mins.... but still, it's one of those jobs. Let us know.

    PS....just a thought. The return rail on the nozzles themselves has a alluminum washer that has a pin-prick of a hole in it. These are special washers and the tiny hole must be there or else the injector nozzle can't return excess fuel to the tank. I've made these washers before from regular alluminum washers from the carby shop and a small drill bit in a battery drill. All this assumes it's the same config as my '98 and my old '90 hiaces.

  3. #3
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    Sep 2006
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    Re: diesel knock with elsbett nozzles

    Quote Originally Posted by 03Hiace View Post
    Looking for help from the forum.

    I recently fitted some elsbett injector nozzles and the engine now knocks. It has never knocked before. I fitted the new nozzles with the aim of reducing gumming problems.

    One option is to put the old injectors back in, but I would prefer to get the elsbett nozzles working in the hope of having no more gumming.


    Any help in understanding or fixing this proplem would be much appreciated.

    Thanks
    To be able to help here, I'd like to ask...

    Did you have any gumming problems to start with?

    Your system is designed with a return delay on change over.
    which means that you never start the van on cold oil.

    Why do you think injector nozzles alone could cause or prevent gumming?
    And finally ... What is so special or different about elsbett nozles?

    Would you kindly share new nozzles specs please.
    Fitian
    <><

  4. #4
    Join Date
    Nov 2008
    Location
    central coast
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    Re: diesel knock with elsbett nozzles

    03Hiace i,m only guessing here , but after reading about this on the merc forums when you put in new tips and raise the pressures you have to recheck the timimg . As raising the pop off pressure will effect the timing. From what i,ve read advancing the timing slightly when using veg makes for smoother running.

    Pete
    Last edited by mussopete; 25th June 2009 at 09:09 AM.

  5. #5
    Join Date
    Aug 2008
    Location
    wa. usa
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    36

    Re: diesel knock with elsbett nozzles

    Have you checked your timing? pop test the injectors before you installed them? just a thought ...
    Omar
    www.omarsales.com

    diy pop tester
    Injection Pump Timing Adjustment for Mercedes 617 Engines - Topic Powered by Eve For Enterprise

  6. #6
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    Jul 2008
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    Nelson Bay & Sydney
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    Re: diesel knock with elsbett nozzles

    Hi Tbird

    The nozzles look very similar. The tip of the denso nozzles protrudes about 1-2 mm from memory and the elsbett needle sticks out about 10 % less compared side to side. The only other noticeable difference is on the needle. Both have three transitions in the needle diameter, ie four diameters and the second smallest diameter has a flat spot. On the denso needle, 80 % of this is ground flat leaving a small ridge toward the pointy end. The elsbett is ground flat over the full length of the second smallest diameter... A bit hard to describe. The differences between the nozzles and needles are only just noticeable holding them side by side!

    The ally washers were replaced, but could be damaged/restricted. Could a blockage to the return to the IP cause these symptoms?

    Hi Fitian

    Did you have any gumming problems to start with?

    The gumming (of the nozzles) problem has been there from the start. I check the spray patterns on the injectors every 5000 kms with a diesel injection specialist. The reason for this is to keep a close eye on everything thatís going on. A few times the injectors have had minimal gumming and reasonable spray patterns, a few times they are fanning a bit and once one of them was a pisser.

    Never had a cold start. Each 5000 km interval has been a test of different things: eg stopping/starting on veg with the engine warm/hot, only stopping on diesel, different purge times, using water injection, etc.

    Although the spray patterns vary there has been no noticeable difference to the feel of the van or to acceleration times. Each time I test the injectors I do a compression test and the results are the same.

    Why do you think injector nozzles alone could cause or prevent gumming?
    And finally ... What is so special or different about elsbett nozles?
    My hope is that nozzles designed for veg will perform well with veg. Maybe I'm being too fussy and maybe the injectors will just gum on diesel anyway!!

    The nozzles are very similar to the denso ones

    Would you kindly share new nozzles specs please.


    The nozzles are the ones sold by elsbett for single and two tank systems for this engine.

    Hi Omar and mussopete,

    I had the nozzles set at 165 bar by the injection specialist. The timing advance was increased by 3 degrees about nine months ago. The timing itself has not been changed. I havenít checked the timing since. Doesnít knocking suggest the timing is too advanced already?

    Thanks for the replies so far

  7. #7
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    Sep 2006
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    Sydney
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    Re: diesel knock with elsbett nozzles

    Paul,

    I really do admire your care for your van. Keep it up.

    Is the nozzle from elsbett made by them and designed for wvo?

    If this was the case, then I would then see a point in changing your old ones. But if you have not noticed any difference between the old and the new nozzles then I guess you need to look at using injectors cleaners as regular service routine.

    Your test results and performance are the same every time - this is good do not you think?
    Fitian
    <><

  8. #8
    Join Date
    Apr 2006
    Location
    New Zealand
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    Re: diesel knock with elsbett nozzles

    Could a blockage to the return to the IP cause these symptoms?
    It did with my '98 hiace. The problem came about when those ally washers became so "swaged" from continually removal and refit of the banjos that one of the tiny holes closed over. New Toyota ones were an arm and a leg so I made some....easy. It took a couple of weeks to nail that one down. Yeah, I think smoke was one syptom. Finally I was able to diagnose the problem to one cylinder by cracking off each injector line nut in turn. Then I swapped that injector nozzle with one of the others. Still the prob was with that cylinder..... but it told me the nozzles were OK. Then I reasoned that maybe the washers were suspect. These are not ordinary banjos in the normal sense.... unlike say a carb banjo. These toyota washers have to have that approx 1mm pinprick of a hole.... otherwise excess fuel can't escape and will be forced into the cylinder.
    See attachment for washers pic.
    I hope it's as easy as that. I suppose it could be if all 4 washers had been replaced with plain ones.
    Doesnít knocking suggest the timing is too advanced already?
    That's certainly one cause. Other would be if fuel was entering by other means.... or possibly left over from a previous stroke. I guess that can come about when combustion is incomplete because the nozzle spray is not good.

  9. #9
    Join Date
    Jul 2008
    Location
    Nelson Bay & Sydney
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    Re: diesel knock with elsbett nozzles

    Thanks for the replies everyone.

    I'm near Darwin now and the engine is running great on diesel. Having a break from veg. Will try and make time to investigate further in Darwin.

    Cheers

  10. #10
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    Update: diesel knock with elsbett nozzles

    Finally got the timing checked on a dyno with some interesting results.

    Running on diesel the idle timing is set at 3.5 deg and at full open throttle it only advances to 4 deg.

    On veg the idle timing is 5 deg and at full open throttle it advances to 10 deg.

    I've just had the Elsbett injectors checked after 15K (11K diesel and 4K veg) and they are spraying like new (Tbird: The return line and washers were all clear.) The pop pressures are still good.

    The diesel knock only happens on veg and only in low revs (up to about 1600).

    I'm considering retarding the timing a bit.

    What do you guys think?

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