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Question about lifter noise

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by NerdBoy, Aug 8, 2003.

  1. NerdBoy

    NerdBoy 1/2 ton status

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    The 350 under my hood has (according to the previous owner) a Crane Energizer 272 hydraulic cam. Lately, I have noticed what sounds like a lifter tapping (but this is just a guess, it is difficult to hear over the noise of the gear drive)
    I talked to the previous owner about the history of this truck, and he told me that he "adjusted the valve lash" on this engine when he put the camshaft in.

    My questions:
    1) I was unaware that there was any valve lash adjustment on a hydraulic setup. Is it true that the valve clearance needs to be set, and, if so, what should it be set to?

    2) A semi-reliable source told me that I should "expect valve noise from any engine that has a long-duration camshaft" I find this hard to believe, and, considering the source, I must ask you guys: What type of noise (if any) should a healthy vavle train be making?
     
  2. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    1. You do need to adjust valve lash in a "hydro setup". Refer to the MFG. specs for lash measurements. Here is a good link on setting lash:

    http://www.73-87.com/garage/valvlash.htm

    2. I don't have time to look up your cam specs on the 272... but I can tell you from expereince that it takes a pretty RADICAL cam before you have to accept valvetrain noise as a standard thing. I'd guess that you aren't in that ballpark in this case.

    If it were my truck, I'd redo the lash... It certainly can't hurt anything. Sometimes it just loosens up...

    The only other bad bit of news here is you should check EACH pushrod individually BEFORE removing the rocker nuts to be sure that one or two are loose. If you find that there are a couple loose pushrods... be leary of a fried cam. Every once in awhile, a cam will start to loose a lobe or two... and that will cause you BIG problems. I'd get in there and take a peek at it.

    Just my .02!
    /forums/images/graemlins/grin.gif

    -Dan
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    I don't know as you'll ever hear hydraulic lifters in operation (properly working), except maybe the anti-pump up styles, which apparently can be slightly noisy.

    Basically hydraulic lifter lash is set by attaining 0 lash, then going 1/4 to 1 full turn tighter on the rocker arm nut.

    If the problem just started, make sure it isn't an exhaust leak.
     
  4. NerdBoy

    NerdBoy 1/2 ton status

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    Thanks for the information.

    Actually, I thought it was an exhaust leak at first. I just finished replacing all the exhaust gaskets last night.

    The truck has been making this noise for a little while now, and I finally got the time to fix it. One more quick question: I would think that if it were a camshaft lobe, I would notice a degradation of performance. This thing has been running strong since I bought it, and the spark plugs read normal. If it were a camshaft lobe, are there any other symptoms that I should be looking for?
     
  5. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    [ QUOTE ]
    If it were a camshaft lobe, are there any other symptoms that I should be looking for?


    [/ QUOTE ]

    The only quick way I could think of... would be to do an oil change, and look for any signs of metallic (silverish) debris in the oil...

    On the performance thing... YES usually once the lobe(s) start to go, you will notice a decrease in performance. The motor anlomst sputters when you give it gas when it begins to get bad.

    I'd just adjust your lash, and start there. /forums/images/graemlins/thumb.gif

    -Dan
     
  6. loudnowlouder

    loudnowlouder 1/2 ton status

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    you might want to pick up a mechanics stethoscope to help find the noise...if its not the exhaust leaking you'll be able to pinpoint the noise over the gear drive....
    i picked one up from advance auto parts for 10 bucks....i've yet to need it, but from playing around with it i've noticed it sure works a lot better than the old broomstick trick!
     
  7. SUBFAN

    SUBFAN 1/2 ton status

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    Heater hose....
     

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