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Engine knock with warm engine only

Discussion in '1st Gen. Tacomas' started by andoskyy, Nov 10, 2011.

  1. Nov 10, 2011 at 7:14 AM
    #1
    andoskyy

    andoskyy [OP] Well-Known Member

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    Hi All,

    I did some searching and couldn't seem to find anything equivalent to my scenario.

    I have a 1996 3.4l 4x4 with 130,000k. Recently, I've been getting an engine knock at idle when it reaches full operating temperature.

    I seafoamed the vehicle through the vacuum line and gas tank a few weeks ago. Smoothed out my idle and acceleration, but didn't do anything for the knock.

    I'm thinking this could be an oil viscosity issue? Has anyone switched oil weights, or has anyone had a similar scenario/solution?

    Thank you
     
  2. Nov 10, 2011 at 10:03 AM
    #2
    TacoMX

    TacoMX TW's Official anti body-lift pundit

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    what kind of oil/filter are you running?
     
  3. Nov 10, 2011 at 10:30 AM
    #3
    andoskyy

    andoskyy [OP] Well-Known Member

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    Castrol GTX high mileage semi synthetic, 5w-30 with a Purolator oil filter I believe.
     
  4. Nov 10, 2011 at 10:34 AM
    #4
    TacoMX

    TacoMX TW's Official anti body-lift pundit

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    what weight oil?

    I ran a purolator "pure one" filter and had a knock at idle when using it, its known as a pretty restrictive filter (compromising flow for filtration). Although mine went away when it was at operating temp.

    Use toyota filters, I have heard from many that knocks while using aftermarket filters went away when they switched to a toyota filter.
     
  5. Nov 10, 2011 at 10:34 AM
    #5
    BlueT

    BlueT Well-Known Member

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    Silly question but when timing belt was replaced ?
     
  6. Nov 10, 2011 at 10:36 AM
    #6
    andoskyy

    andoskyy [OP] Well-Known Member

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    edited my reply, 5w-30.

    im due for an oil change this weekend. will switch to toyota filters...worth a shot.

    timing belt was changed at 91k. if it was a timing issue, wouldnt it knock when cold as well?
     
  7. Nov 10, 2011 at 10:42 AM
    #7
    BlueT

    BlueT Well-Known Member

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    Probably no because at cold computer uses different timing. When does it knock? all the time (even at idle) or only when you driving up the hill and engine is under heavy load?
     
  8. Nov 10, 2011 at 10:46 AM
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    andoskyy

    andoskyy [OP] Well-Known Member

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    I've only noticed it at idle when things are quiet. Once I take off from a start, things are perfectly smooth and no noises out of the ordinary.

    I'll take a better listen tonight on my way home though.
     
  9. Nov 10, 2011 at 11:18 AM
    #9
    BlueT

    BlueT Well-Known Member

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    What happens if you rev up in park. Does noise gets louder?
     
  10. Nov 10, 2011 at 11:24 AM
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    andoskyy

    andoskyy [OP] Well-Known Member

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    louder, no, but more rapid. As soon as I start moving, it drowns out very quickly.
     
  11. Nov 10, 2011 at 1:02 PM
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    skytower

    skytower Well-Known Member

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    Hitch and wiring, aux back-up light, rear strobe lights, radio and underseat sub.
    Verify your temperature sensors are working properly as well as your oxygen sensor. Temp sensors modify your fuel mixture and timing. They can start causing problems before they set a CEL.
    Check your plugs, and wires for wear and arcing, too.
     
  12. Nov 10, 2011 at 5:53 PM
    #12
    saweetlou

    saweetlou Well-Known Member

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    Not trying to hijack this thread but what would this have to do with anything, I ask because I dont know when my belt was done and I wasnt aware that there were any signs that would let me know if the belt was going.
     
  13. Nov 10, 2011 at 6:00 PM
    #13
    TACOMABOSS

    TACOMABOSS Well-Known Member

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    piston slap maybe?
     
  14. Dec 21, 2011 at 10:35 AM
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    andoskyy

    andoskyy [OP] Well-Known Member

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    hi all, quick update.

    switched to toyota filters and still have the knock.

    cleaning MAF and throttle body this weekend as I read this can cause a similar knock.

    Will update next week.

    Thank you for the suggestions.
     
  15. Mar 1, 2012 at 6:50 PM
    #15
    uberjason

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    Any update?
     
  16. Mar 2, 2012 at 4:27 AM
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    andoskyy

    andoskyy [OP] Well-Known Member

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    sorry for the lapse in posts.

    Cleaned the throttle body, and while the truck ran better and I got better throttle response, the knock is still there.

    Another thing I noticed is that I can only hear the knock inside the vehicle. Its not an aggressive knock and must be coming from the back of the engine.

    Next on the list is to change the spark plugs again. Did it about 5k ago, but maybe seafoam gummed them up or something...who knows...cheap experiment.

    if it still there, i'll bring it to someone to see if its a valve adjustment issue.

    will do my best to remember to update the post!
     
  17. Mar 2, 2012 at 6:15 AM
    #17
    Wild Card

    Wild Card Truck yeah!

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    You *may* have a bent connecting rod. I know, these engines are bullet-proof, yada-yada-yada. But that still is a possibility, and used to be a common occurence of knock.

    Have you tried running premium in it? You could be, for some reason, experiencing some detonation in the cylinder. Perhaps you have a large amount of carbon build-up in one of the combustion areas (I know, you seafoamed, but it could be a big mother). That would, in turn, ramp up the compression ratio in that one cylinder. Higher compression = higher chance for knock when using lower octane fuel.

    I'm just trying to sort out all possibilities for you. 2-strokes suffer from this frequently, due to burning of cheap oils (not me! I always run expensive synthetic crap in my 2-strokes!).

    Also, a valve could be on its way out. Camshaft bearing. Crank bearing. Connection rod bearing. Wrist-pin for the piston. Etc. I sincerely hope it is none of these physical problems, but, if it turns out to be, get them replaced ASAP. One little bearing problem or bent connecting rod can equal the end of your engine's life, usually at the worst possible time (dropping kids off to school, going to work, trying to hide a dead body...)

    Good luck, and let us know if anything changes.
     
  18. Mar 2, 2012 at 7:21 AM
    #18
    andoskyy

    andoskyy [OP] Well-Known Member

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    Thanks Wild Card, surely something else to consider.

    I have a feeling its a minor issue, like sensor or valve adjustment. Its not aggressive, runs perfect when cold, and can't hear the knock outside.

    i'll likely have it checked out by a foreign motors specialist down the street from me if new plugs and another seafoam doesnt help.

    thanks again,

    Andrew
     
  19. Jul 16, 2012 at 11:11 AM
    #19
    andoskyy

    andoskyy [OP] Well-Known Member

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    ok, so knock is gone...thank you for all the suggestions.

    Even though I did a spark plug change about 5k ago, I did another one...and also changed the wires. Previously, I used the OEM NGK plugs which are single electrode. this time, I used the Denzo dual electrode OEM plugs. so between those plugs and the new wires, all better.

    so for those of you that think you may have the valve tick, its worth the $15 to try out the Denzo plugs. If that's not it...new wires after that. Just happy it was a $60 fix and not a valve adjustment.

    Thanks again for all your input.

    Andrew
     
  20. Aug 29, 2012 at 5:15 PM
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    Tacoma2525

    Tacoma2525 Member

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    Andoskyy: did yours only do it when the ac compressor was on? Mine does it with the ac on, truck in drive. I also have the ngk plug wires on it. But yes it only does it when the motor is warmed up.
     
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