Dreaded VVT Rattle, but a different question...

Thread in 'Technical Questions' started by smoody, Mar 11, 2013.

  1. smoody

    smoody Member

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    Hi guys,

    After scouring the internet for hours i stil cannot find any answers to what im curious about.
    I got some bad A** VCT rattle and managed to get hold of a second hand sprocket after a few months of living with it.
    I fitted it last night and all is well but still plays up when oil pressure is low on the first startup.

    My question is, is there any way to increase the oil flowing to the VCT sprocket without removing the head? i cant seem to find any info on if it is possible to do so?
    From reading up it sounds like its possible to have some crud building up reducing the oil flow but people only really talk about cleaning out the port when the head is removed.
    Can anyone point out where the VCT sprocket oil feed is for starters.

    Any info would be much aprechiated, im sure someone else must have thought of something similar!
     
  2. Munkul

    Munkul Active Member

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    you need to learn how the system works. It is very unlikely that it is crud blocking it up.

    Cure VCT sprocket rattle for £10 is an option, try at your own risk.
     
  3. smoody

    smoody Member

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    What do you mean by system? The vct system? I was under the impression it was in one position at idle (rattles) and another at higher rpm (silent) and it may be unlikely but if the sprocket is starved of oil then I would presume it would deteriorate faster?
    That switch is quite a clever idea but really I'm looking for a way I can try and prevent it getting to this point in the first place.
    Thanks for the link though!
     
  4. Munkul

    Munkul Active Member

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    yes, that IS the system. (people call it VVT, its proper name is VCT) It works by being ON nearly all the time, and only OFF above 5700rpm, and also at idle in neutral with no throttle.

    That is why it is very unlikely it is blocked, cos it is guaranteed to activate every time you drive the car. Unless your solenoid is not working, in which case you will have less midrange torque.

    There is no way of preventing the sprocket deteriorating with wear, as far as anyone can make out... unless constant activation at idle helps, since it provides a cushion of pressured oil for the splines inside the sprocket. It certainly is the reason why a worn sprocket is silent on activation.
     
  5. smoody

    smoody Member

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    Ahh I see, that is great help thanks :) I'm guessing it is the lack of oil cussion that causes the problem in the first place?
     
  6. Alex B

    Alex B Active Member

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    Even with an Accusump?

    Alex B
     
  7. Munkul

    Munkul Active Member

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    That wont make a shed of difference to the VCT system. If you run low on oil pressure then the VCT is the furthest thing away from your worries lol
     
  8. Alex B

    Alex B Active Member

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    But what about pressurising the system on ignition, so should get oil round the sprocket before it starts moving, ie, causing wear?

    Alex B
     
  9. Munkul

    Munkul Active Member

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    Well yeah thats a good idea, but to be active on ignition you would need to fit a switch like i have. It only activates over certain conditions, and isnt active without the engine running.

    For the record, nistune will NOT let you have vct on at idle unless you cancel both the neutral and tps idle switches. Which isn't practical.

    Sent from my personal telephone, like a boss.
     
  10. kam

    kam I've touched Chris Parry

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    Get the later solenoid that has larger oil ways before it wrecks the new sprocket.
    I think it's the solenoid that causes the wear anyway, because:

    1) I had rattle, swapped for a new solenoid and it went away
    2) Nissan revised it
     
  11. smoody

    smoody Member

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    What year did they start puting the modified solenoid on?
     
  12. kam

    kam I've touched Chris Parry

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    S15's I think.

    *Revised PN is 237961N515
     
    #12 kam, Mar 13, 2013
    Last edited: Mar 13, 2013
  13. Alex B

    Alex B Active Member

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    I think it's S14a that had the later solenoid, mine did. The earlier ones had a non return valve too.

    Do you know for a fact that the later ones have larger oilways? When I changed my sprocket I changed for an earlier solenoid and it stopped making the buzzing on initial start up.

    Alex B
     
  14. kam

    kam I've touched Chris Parry

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    It was something like that, it's different I know that much :wack:
     
  15. Alex B

    Alex B Active Member

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    I've only heard the later ones did away with the non return valve, not heard any other differences, if it's not something you've already checked I'll have a look when I get a minute so we know :)

    Alex B
     
  16. Munkul

    Munkul Active Member

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    interesting. I hadnt heard about the revised solenoid. Failure of the old solenoid is fairly common, though.

    Regardless of this, when the solenoid is active, the system is pressurised and the sprocket doesnt rattle.
     
  17. Alex B

    Alex B Active Member

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    Here's a picture of the old and new, you can see the extra bit on the front of the S14 one, which houses a little ball bearing. Once it's running it will make no difference, it's on initial startup etc when it should, (and from what I've heard on mine it does), thats also when most of the wear will happen due to oil draining away from the sprocket.

    [​IMG]

    Alex B
     
    #17 Alex B, Mar 13, 2013
    Last edited: Mar 13, 2013
  18. Munkul

    Munkul Active Member

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    That's a bit confusing.

    The later design doesnt have the NRV, but keeps the oil in the sprocket better? That doesn't compute. An NRV will hold the oil back, non-NRV will allow it to drain...?

    I wonder if its designed to allow a little amount into the sprocket to lubricate it on start-up, and the later design just allows more flow/pressure? Anyways, Meh, I'm sorted :p
     
  19. Alex B

    Alex B Active Member

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    No, I think it's accepted, (and I agree from my experience), that the earlier design is better, (with NRV), no idea why they changed it, cost cutting maybe.

    Alex B
     
  20. smoody

    smoody Member

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    I was thinking the same thing... But if it works I can't complain! Ill get shopping then :p
    Thanks for all the info gents!
     

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