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Constant pitch whistle under throttle

Discussion in '80-Series Tech' started by rdublin, Mar 4, 2007.

  1. rdublin

    rdublin

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    I have developed a constant pitch whistle (about the high E string on a guitar) in my '96 FZJ80, but only when the throttle is applied. The volume increases with the throttle, but the pitch stays pretty much the same. It started a few weeks ago and has become progressively louder. The sound appears to be coming from the rear half of the engine compartment, but is not present when the engine is cold. I also cannot generate the sound either by reving the engine without load nor by reving the engine while in gear with the brake applied - I must be moving at least 10-15 mph.

    A vacuum leak came to mind, but I would think that would be worse at idle (when manifold vacuum is the highest) and this gets worse with throttle. Maybe I am missing something here? I have had an intermittent P0401 which I will be trouble shooting this afternoon, but I've had that for some time and the whistle is only a few weeks old, so I am assuming they are not related. I checked the tranny level yesterday and found it it be 1/2 qt low, so I suspected the torque converter may be the source. However, the noise persists after bringing the tranny up to the fill mark.

    I've struck out searching the Mud archives, but it could be I am not using the correct keywords (whistle, throttle).

    In any case, I am at a dead end and am looking for ideas.

    Thanks!
     
  2. landtank

    landtank SILVER Star

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    it's in the exhaust, not sure what and opinions vary, but it's in there.
     
  3. 96landcruiser

    96landcruiser

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    Most likely an exhaust issue.............. getting mine fixed next thursday found a leak the other day. Good luck

    kunal
     
  4. rdublin

    rdublin

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    That would be great as it is one less thing I have to do before heading to Baja at the end of the month. I'd be the first to say my exhaust system is beat to crap, so that would not surprise me. I'll go mess with it to see if I can change its behavior. Any keywords you would recommend to find previous discussions on the subject?

    Thanks!
     
  5. rdublin

    rdublin

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    One additional comment - I had my family line up on the sidewalk to listen as I drove by (a couple times in both directions) and they all claim the sound is coming from the front of the truck. Anything in the exhaust path to whistle up there?

    Cheers,
     
  6. landtank

    landtank SILVER Star

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    LOL, I wouldn't trust anyone in my family to know the difference. Hell, I wouldn't trust my wife to drive by without running me over so I could tell the difference.
     
  7. chibo

    chibo

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    Exhaust manifold gasket, gasket between header/exhaust. Just start the truck up and move your hand around where pipes meet in the exhaust - you'll feel the exhaust coming out.
    I've got a whine under throttle but it's the fuel pump ;)
     
  8. rdublin

    rdublin

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    Well, that worked! :) Turns out the leak is on the inside of the "Y" where the two exhaust manifold pipes merge into the single exhaust pipe (so my family did get the location right! :D ) I assume that is a Toyota part and not something I can get easily fabbed at a muffler shop? I am thinking of wrapping it with muffler tape (assuming they still make the stuff) for my Baja trip. Any other approaches?

    Cheers,
     
  9. landtank

    landtank SILVER Star

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    I had a crack there myself but didn't get a whistle from it. I removed the front section and had it welded. Easy fix and it cost something like $50.00.

    That front pipe includes the cats so it is crazy expensive, get it welded.
     
  10. fzjchase

    fzjchase

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  11. rdublin

    rdublin

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    Well, I don't know for a fact that is where the whistle is coming from, but it blows pretty good just at idle. I'm going to tape it up a bit and see if that squashes the whistle. If so, great. If not, I suppose I'll keep looking....
     
  12. landtank

    landtank SILVER Star

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    You found a problem with the truck that needs to be fixed. That crack will allow air to enter pre O2 sensor and screw with your trucks running. The front pipe comes out rather easily and it needs to be repaired.

    Come back to the whistle when that is done.
     
  13. rdublin

    rdublin

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    I wrapped some aluminum foil in and around the "Y" this morning before heading to work. At this point, the whistle is gone. I'll see how things go as the day progresses and will advise.

    Didn't think about the effect on the ECM. I'll look at pulling it off this weekend and welding it.

    Cheers,
     
  14. rdublin

    rdublin

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    Well, I got in there, cleaned up the area around the Y, and found that it was cracked at least 120 degrees around the front pipe. The crack is right along the factory weld bead and disappears between the two pipes as well. I ground and rewelded as much as I could without removing the exhaust, but it is still obviously leaking between the two pipes. At this point I am going to apply muffler patch in the area between the pipes and hope it holds for a bit. When I return from Baja in April I will pull the whole pipe, but I'm not even sure you could get in there to weld between the pipes even with it on a bench. My neighbor suggested brazing in that area, which might actually work, but I'll probably have to pull it to do that as well.

    Has anyone successfully repaired a crack in this area or am I looking at a rather spendy new part?

    Cheers,
     
  15. landtank

    landtank SILVER Star

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    Yes, as stated in my earlier post. You will need to remove the pipe to get at that area though.
     
  16. IronYuppy

    IronYuppy

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    I lost my resonator a while back, and the result was an immediate whistle (don't know the pitch; I'm not a musician).
     
  17. rdublin

    rdublin

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    Was the crack in yours in the very narrow area between the pipes? I can't see how that could be welded, except for maybe gas welding.

    Thanks,
     
  18. landtank

    landtank SILVER Star

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    yes, right in the crotch of the "Y". I had professionals do it. I brought them the pipe in hand.
     
  19. Cruzer_89

    Cruzer_89

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    I got the same freakin whistle. Will this possible crack cause me to hear the valves chattering at low RMP's?
     
  20. Cruzer_89

    Cruzer_89

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    Oh C'mon............ Im not feeling the Love here. Could the valve chatter i'm hearing be coming from that small leak that causes the high pitch sound???

    Somebody tell me something.....


    Please. please...........