pushrod knock

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    Author Topic: pushrod knock  (Read 2023 times)

    Offline 71chmark

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    pushrod knock
    « on: February 21, 2009 - 09:26:32 AM »
    When I first start up the 440 several of the pushrods knock (verified with valve covers off).  After it warms up they quit.  I have the thicker pushrods with the 1.7 roller rockers.  Wondering if it’s OK to leave it like this.  Pain in the butt to remove and replace the heads (906) for clearancing.  I’m afraid I might take too much or not enough off also.   Other options are shim the rockers away but this will move them off center of the valves and I’m not sure I’ll have enough room anyway.  I’ll try this first.  I could go to 1.5 or back to stock valve train.   Won't get into this for a couple of months.  Soooo Cooooooolldddd.  Just thinking ahead and looking for suggestions.
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    Offline 71chally416

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    Re: pushrod knock
    « Reply #1 on: February 21, 2009 - 10:08:19 AM »
    So I'm guessing they are pushrods are hitting the heads??
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    Offline 71chmark

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    Re: pushrod knock
    « Reply #2 on: February 21, 2009 - 10:24:02 AM »
    Yes.  Some are tapping against the sides.
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    Offline The Cuda Guy

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    Re: pushrod knock
    « Reply #3 on: February 21, 2009 - 10:59:24 AM »
    To me it sounds like all roads lead to take the heads off.  You bought the rockers for a reason, you dont want to waste that money. 

    Don
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    Offline 71chally416

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    Re: pushrod knock
    « Reply #4 on: February 21, 2009 - 11:06:43 AM »
    It's unlikely you will "take to much off" if you grind the heads a little where it rubs. If you're slick you can do it without taking the heads off. Pull the Intake and stuff a rag in the lifter valley first then suck the metal particles out with a shop vac before removing the rag. 
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    Offline 73EStroker

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    Re: pushrod knock
    « Reply #5 on: February 21, 2009 - 11:38:46 AM »
    Life always deals the bad cards first ......... if it were me I would take the heads off. One small piece of crap down below and it will be worse than taking the heads off.
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    Barry (Salmon Arm)

    Offline 71chally416

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    Re: pushrod knock
    « Reply #6 on: February 21, 2009 - 11:41:21 AM »
    Thats what the oil filter is for.  :2thumbs:
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    Offline lemming303

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    Re: pushrod knock
    « Reply #7 on: February 21, 2009 - 03:30:25 PM »
    What exactly is "pushrod knock"? I don't know too much about engines yet, I'm slowly teaching myself.
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    Kevin

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    Offline The Cuda Guy

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    Re: pushrod knock
    « Reply #8 on: February 21, 2009 - 04:30:06 PM »
    Quote from: lemming303 on February 21, 2009 - 03:30:25 PM
    What exactly is "pushrod knock"?

    They sound like this.... tick tick tick tick with the rev of your engine.  It is the most annoying noise you will ever hear!  First you will think its your lifters??? or header gaskets....  but then you realize its your push rod taping the heads for one various reason or another one of them being one rocker arm on L that should be on the R and vice versa!  Dont ask me how I know this....  

    :swear:    :faint:    :walkaway:   :1zhelp:   :misbehaving:   :woohoo:   :burnout:  Its a vicious cycle.

    Don
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    Offline Moparal

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    Re: pushrod knock
    « Reply #9 on: February 21, 2009 - 04:30:45 PM »
    I would think it would be more of a scrape. If the rockers were hitting, then maybe a tap tap tap
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    Offline The Cuda Guy

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    Re: pushrod knock
    « Reply #10 on: February 21, 2009 - 04:33:50 PM »
    Quote from: Moparal on February 21, 2009 - 04:30:45 PM
    I would think it would be more of a scrape. If the rockers were hitting, then maybe a tap tap tap

    Alan good point esp. with the 1.7's  But unless you get in there and look at it and see it, you wont know for sure.

    Don
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    Offline 71chally416

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    Re: pushrod knock
    « Reply #11 on: February 21, 2009 - 04:50:42 PM »
    They can definately make a tapping noise if the pushrods hit the side of the head, but it's odd that it goes away when it warms up. Maybe you should pull the pushrods out and look for shiney spots. :thinkerg: Bad lifters can also cause a tap. Pull them out and make sure they are still convex with a straightedge. If they are concaved or "cupped" it's time to replace them.
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    nivvy

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    Re: pushrod knock
    « Reply #12 on: February 21, 2009 - 06:25:32 PM »
    I sold him the pushrods and rockers and am pretty sure they had some slight marks already... yes they can tap the inside of the heads.....  I didnt have a problem before but the pushrod holes were enlarged on my heads... Mark I remember when you first installed them and everything was great with no isses  :clueless: I agree with 71chally416 if you have to enlarge the hole and stuff a rag down there but also add some grease around the pushrod holes to "grab" any metal particles if you go that route...... but the goes away after warming up thing has me thinking its the valves tapping  :working:

    Recheck your lash also......  :working: but enlarging the holes is easy.......  :working:
    « Last Edit: February 21, 2009 - 06:37:15 PM by StRoKer »
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    Offline 71chmark

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    Re: pushrod knock
    « Reply #13 on: February 21, 2009 - 06:36:30 PM »
    Yeah.  They weren't knocking at first because I had no preload.  Once I put a preload on they started knocking.  I'm positive it is the pushrods as we had the covers off and could change or eliminate the sound by applying pressure on the lifters.  Does seem strange that it goes away when warmed up.  The lifters are all new.  I suppose it could be the valves but they are pretty far down in the hole and I did the piston to valve clearance you outlined and had no issues.  When it gets warmer out I'll mess with it some more. 
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    nivvy

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    Re: pushrod knock
    « Reply #14 on: February 21, 2009 - 06:39:50 PM »
    I would do the pushrod enlarging first then if your sure of the pushrod tap...... cant go wrong there and i think those were 3/8 comp pushrods...... If the tapping is still there im leaning towards the valves.... didnt you get a set of milled 906's off ebay ??? not the valves "tapping" the pistons but tapping in the combustion chamber "opening and closing" of the valve.....
    « Last Edit: February 21, 2009 - 06:43:48 PM by StRoKer »
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