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The infamous Ford Explorer OHV knock/tap

Discussion in 'Stock 1991 - 1994 Explorers' started by ernzo, August 19, 2008.


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    1. ernzo

      ernzo Active Member

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      I have spent time searching and reading on this. I am posting this new thread as I guess I am not really getting anywhere and have basically stopped driving the EX until I can figure this out. :(

      I have done 2 rounds of Seafoam through the intake, my neighbors are questioning. I am sure it helped something, but not this noise.

      The sound is not present at startup. It is present after things warm up, the warmer the louder. In order to hear it, I have to drop it into D and rev, while braking. IT DOES cycle with the motor, but does not sound like a rod, not 'heavy' enough. At idle it is about 4 times a second and picks up as I rev up a little while in gear, although I think I can detect it while driving, usually slow on my street where it is quiet. In any event, it is not real loud or real noticeable while driving, but it is very distinct, not the noise of a lifter IMHO, but who knows?:confused:

      I am told (here) that it also may be in the tranny, perhaps the torque converter? Again, I know and have read plenty of posts on this, and I guess I am thinking 'lifter not pumping up' but I want to eliminate rod knock and be assured that a flat lifter will not hurt me while driving as long as I take it easy?

      Ideas?? Thanks in advance and I also looked on you toob to see if I could find a video of my sound, and I could not. Anybody know of one?
       
      Last edited: August 19, 2008
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    3. briwayjones

      briwayjones Manual Master

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      Hmm, if you have to put it in gear to hear it than it's not the typical lifter noise. Which would likely means it has something to do with the tranny.
       
    4. Masterd

      Masterd Active Member

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      If you can, get an audio clip.
       
    5. mshuler009

      mshuler009 Active Member

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      I too just had this probelm arise yesterday. I didn't get it to do it yesterday because I had it in park. But when driving it today I heard it. So I powerbraked it slightly and hear a really soft sound louder than valve noise but quieter than a rod knock.....I'll try to get sound
       
    6. Masterd

      Masterd Active Member

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      I might know what sound youre talking about...

      Try and get that clip.
       
    7. seth247

      seth247 Well-Known Member

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      I also have a noise that I fear is not a lifter noise.

      However mine is present at startup.
       
    8. Blacksheep Josh

      Blacksheep Josh Slinky+Escalator=Fun Elite Explorer

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      i have a tapping sound from the engine and got two opinoins from two different mechanics. one said it was a fuel injector clicking, another said it was a lifter. but both agreed that i shouldn't worry about it with the amoutn of miles i have on the engine.

      you might try the stethoscope method. it's like one a doctor uses but it's a little tube you can put against the engine, you might be able to pinpoint about where it's coming from. if it gets louder the warmer it is, then chances are it's making the sound at all times, you just can't hear it. the stethoscope should make it easeir to hear it when parked.
       
    9. ernzo

      ernzo Active Member

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      Update NOW WITH VIDEO / AUDIO !!

      http://media-mobi.com/en/?play-bk4v5l5g322fcx7kldozxw3kjc07d7nv

      and another

      http://media-mobi.com/en/?play-7l7qgbls5tszepocpga038ohis2ttjk5

      This is with me holding the camera phone while sitting in the drivers seat. I have the brake on and and reving about 1000 or so.


      Masterd: I (now have) an audio/video clip of the sound that I can post. I regret that I have yet to do the steth-test ( I use a long piece of wood), but I talked to my wife about helping me today and will check. ;)

      This is no fuel injector tap that I have ever heard, but I do know that noise.

      Briwayjones: You mention the typical lifter noise as (likely) to be heard at all times, and I agree, although this is my first explorer and I am not real familiar with all the noises.

      Anyway, I have the video and will try to post this am.:salute:

      Thanks!!
       
      Last edited: August 20, 2008
    10. Shen2187

      Shen2187 Active Member

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      Sorry but I have no idea what that noise is. But I can tell you it doesn't sound good. :(
       
    11. mshuler009

      mshuler009 Active Member

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      I've tried the TSB on the carbon knock on acceleration. Cured it. Runs faster than a mechanic from the toolman....lol
       
    12. ernzo

      ernzo Active Member

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      Torque Converter Bolt(s) loose?

      Let's say the noise is tranny, and it is loose torque converter bolts (one possible diagnosis)

      Can I tighten them? Without taking out the tranny (T-case etc. etc.)?

      Ideas???:eek:
       
    13. allout

      allout Member

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      My diagnosis would be either loose torque converter bolts or a cracked flex plate. On the older trannys there was an inspection/access plate, if not then just remove the starter to get at the bolts.
       
    14. Masterd

      Masterd Active Member

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      If thats not a cracked flexplate (which is somewhat common, considering its construction), then I'd say bottom end noise.

      Hows power? Does it smoke? What RPM is the noise loudest at?
       
    15. ernzo

      ernzo Active Member

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      Flex Plate inspection

      Allout: I will climb under it this weekend and look for an inspection plate. As I have never actually done anything to a tranny, except some peripheral stuff, I assume I look for anything loose (and tighten it up) or anything that is cracked?? As a shade tree mechanic, my experience only goes to jobs I have done, and while I replaced a T-Case, I did not have to take out the tranny to do it!! And it was on a Jeep, not a Explorer. So, new territory.:eek:

      masterd: Absolutely no smoke, runs like a champ, plenty of power has been extremely well maintained over the years by the previous (1) owner.

      When cold, it absolutely does not make the 'noise' - In any gear, or N. This AM, if I started her, and put her in D with the brake on, engine sounds like it was new.:thumbsup:

      When she has been driven for awhile, and I THEN stop, put her in D with the brake on, she makes the noise at idle, and if I apply the gas some, the noise picks up and gets more noticeable. :thumbdwn:
       
    16. Masterd

      Masterd Active Member

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      Check the oil pressure.

      Cold oil is thicker than oil at regukar engine temp. The thicker oil will cushion the noise until it thins out.

      Oil pressure, engine hot and at 2k Rpms, should be at least 40 pounds.

      I'm thinking a cracked flex plate would be making noise 24/7, to at least some degree.
       
    17. Blacksheep Josh

      Blacksheep Josh Slinky+Escalator=Fun Elite Explorer

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      Just one more idea I had, it's not an exhaust leak/tap is it? After hearing that noise it reminded me of the sound my buddy's Dakota has, and he says it's a leak around the headers/engine.

      We can figure this out!
       
    18. Masterd

      Masterd Active Member

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      Agreed with Josh. You need to get us some oil pressure numbers so we can rule out the bottom end and focus on it being:

      A) Lifters

      B) Rocker(s)

      C) Exhaust leak

      D) Flexplate
       
    19. ernzo

      ernzo Active Member

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      Hmmm, well the idiot guage reads about in the middle, and I am not going to be able to get real oil numbers in the short term, however, it does not run like it has oil pressure low enough to cause this noise (like I would know! :))

      I am pretty sure I will be able to better sus it out with a sound test when I am underneath. If it is coming from the oil pan area.....:thumbdwn:

      I will get back on this and thanks everyone for the notes.
       
    20. Aceofdaspades

      Aceofdaspades New Member

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      Well I had a 99 explorer sport, which had that little rattle on start up and the tick while in gear. The rattle turned out to be the starter gear hanging up on the ring gear and the tick turned out to be a bad torque converter which shot metal shavings through out my whole tranny.

      I have learned that the first gen 4.0L have a bad oiling issue with the upper portion of the push rods and eventually wear out causing play and creates a lifter like tapping. My current explorer xlt 4x4 has the lifter tapping issue, I have already replaced the heads, valve train, lifters and push rods and there was no tapping until about the first couple hours. My oil pressure guage is all over the place, but I have heard it is just an on/off switch and is probably faulty; another mechanic mentioned that I may need a new oil pump which is not providing enough oil pressure to inflate the lifters. I have not replaced it yet because it requires pulling the engine, but the sooner the better because the original heads had about six valves that were pounding the valve seats into the head by at least an inch.
       
    21. ernzo

      ernzo Active Member

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      Update, I listened while under the EX!

      Got the Ex up on ramps and had my wife put her in gear, parking brake on, while I listened. I could easily hear the clunking.

      Remember, it really does NOT make the sound until warmed up.

      I listened at the oil pan and heard it, as well as felt it - a slight taping feel in time with the sound. IT seemed to be coming from the rear part of the drive-train, around the bell housing, but I could not be sure. It is real distinct while lying under the ex. :(

      Pull the oil pan?:thumbsup::thumbsup:
       
    22. Masterd

      Masterd Active Member

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      If you can get to it, Id say pull it and check rod caps for play.

      The 4.0's have pretty tough bottom ends, but it can't hurt to check.
       
    23. ernzo

      ernzo Active Member

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      Thanks, I had thought of that, have never done it. IF there is no 'play', am I to assume that the rods are OK? Is there any value in torquing the caps?


      Shoot... I wish I had the $ to just take it in and get it fixed, but I do not.

      Thanks MD!
       
    24. Masterd

      Masterd Active Member

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      As long as the caps are tight, Id rule them out as an issue, but you dont get a real accurate measure from moving them by hand. But itll do as a start. If you find a "loose" one, check the cap bolts if you can (they might be TTY bolts, so you might not be able to do anything).

      Check the pan for the obvious shavings and stuff.

      Have you pulled valve covers and checked for rocker / valve spring damage?
       
    25. Masterd

      Masterd Active Member

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      To be honest I think Ive got the same noise as well :(

      Im thinking rod, but if you can prove otherwise when you pull the pan, PLEASE DO! :)
       
    26. Aceofdaspades

      Aceofdaspades New Member

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      If you can, I would disconnect the tranny from the engine and then start up the engine, If it still knocks then that could rule out the trans pump and/or torque converter.

      Usually a rod would knock regardless of engine temp. Lifters can tap when cold and dissipate when warmed up, but in your case I really believe it is a trans problem.

      Of course your engine could be dieseling, check the timing. Or maybe even piston slap.........so many possibilities. If you want to get ahold of me, cause I'm not on here that much, you can e-mail me at jrryskinner@yahoo.com
      :salute:
       

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