Ideas on what's causing my click/tick/rattle noise?

Slant 6 Engines

  1. halfafish

    halfafish Damn those rabbits, and their holes! FABO Gold Member

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    Since this issue is with my slant I'm posting it here, but it could well be about any engine. Sorry for the long post but I'm trying to give as much background and info as possible to figure out my problem.

    I rebuilt the slant in my 82 D150. It was fully machined by a reputable shop that does know slants. I did the assembly using Doug Dutra's book and my FSM. I watched and helped as @j par put together another of my slants, but this is the first engine I've built by myself so operator error is certainly a possibility. Other than the alternator, everything used on reassembly was brand new parts.

    Once built it fired right up on a run stand for the break-in with no issues. All was well with no leaks so I took it home and installed it in the truck. During the break-in we were working with open headers and hearing protection so if my mystery noise was present it would have been impossible to hear.

    Fast forward to test driving and further break-in. The truck has no carpet at all just bare metal floors, and the shifter tunnel was set in place with two screws since I knew vinyl flooring was going in soon enough. However, that makes for a pretty noisy truck to drive which made this clicking problem harder to notice and hear.

    After 200 fairly gentle miles I re-lashed the valves. I knew I had a loud rattle which turned out to be from the clutch linkage bar going to the throw-out arm. It was too loose making a ton of noise so I snugged it up and that noise went away. However, there was still a noise, best described as a ticking/clicking, like a lifter out of adjustment. Lashing the valves got them back in spec.

    After driving it another 500 miles or so, I still have the clicking/ticking noise and I can't figure out what it is. Here is what I've checked so far at just over 700 miles:

    I just changed the break-in oil and filter for regular stuff, checked the timing, changed the plugs, and fixed a valve cover leak.

    I lashed the valves again after calling OCG to verify the lash. This was done with the engine hot and running.

    I re-checked the head bolt torque, it was good.

    The noise is RPM related. At idle you can hear it, and the faster the engine runs, the faster it clicks. When I get to 2000 RPM or more, the noise becomes noticeable louder and more metallic sounding.

    The noise does not appear to be gearbox or drivetrain related. It will make the noise sitting still in neutral with clutch in or clutch out.

    When assembling the engine, I checked all the torque two times for the main and rod bolts, doing so in 1/3 total torque increments. I don't think I messed that up but I guess anything is possible.

    At the suggestion of a car buddy, I sent in an oil sample for analysis but it's not done at the lab yet so results are forthcoming.

    To further complicate matters, I only have one ear that works (and that one is mediocre at best) which makes discerning the location or direction of sound very difficult. I can sometimes figure it out by which direction is louder or softer, but for me trying to figure this out while the engine is running is nigh on impossible. I have borrowed several pairs of knowledgeable car-guy ears to help find the sound. Some think it's in the valve cover, some the block, and another thinks it's something external to the engine.

    If I have to pull the engine and go through it again I will, but first I want to make damn sure it's not something stupid and simple external to the motor. I'd be pretty pissed to pull the motor, disassemble and reassemble, and still have the noise when done because it's something else.

    I have the truck back on the lift to investigate from the underside. I'm going out there today to look for anything that could be loose and rattling when it picks up the right harmonic frequency. I'm calling over a buddy with good ears to take another shot at finding where this is coming from.

    All that long-winded preamble is to ask if anyone has any suggestions on what could be causing this, and what to check external to the engine. If so, please feel free to chime in.

    As RRR says, thank you and drive through!
     
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    • Alaskan_TA

      Alaskan_TA Well-Known Member

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      A tic sound can be an exhaust leak.

      A possibly related rattle (if it has one) is the heat riser for the exhaust crossover in the exhaust manifold.
       
    • Professor Fate

      Professor Fate Push the button, Max...

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      Just to eliminate anything external, remove the V belts and run it- short time only, you won't have a water pump...
      This will at least eliminate the alternator, water pump, power steering pump and AC if so equipped.
       
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      • theFightingFew

        theFightingFew Always Learning/1975 Valiant Custom/1974 Valiant

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        I had a tick in my 74's slant that increased/decreased with rpm that I couldn't chase down for the life of me... It was driving me insane. It turned out to be the oil dipstick. My kid shut the hood on my dipstick, snapping it right on the "F" in "full" and never told me.... And put it back... So it was springing up and brushing against the crank or something I guess... Pull the stick, no noise... Put it back, noise... The dumbest f'n thing right... But that's what it was... So worth a look...

        On my 75 I also have a "tick" and that is from an exhaust valve not seating correctly... When the car is idling put your hand or a piece of paper over/near the tailpipe... If you feel or see sucking back into the exhaust the valve isn't seating or is bad...
         
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        • 69FBCuda

          69FBCuda Yup

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          Lets get some video/audio on here.
           
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          • Dana67Dart

            Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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            I would assume the valve train has hydraulic lifters... Why would you have adjustable rockers?
             
            Last edited: Dec 19, 2021
          • j par

            j par Well-hung Member

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            Slant sixes usually have solid lifters and I believe his has hydraulic...
             
          • j par

            j par Well-hung Member

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            A collapsed hydraulic lifter...??
             
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            • halfafish

              halfafish Damn those rabbits, and their holes! FABO Gold Member

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              I will check for exhaust leak but no heat riser, it has headers.
               
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              Even in the 80s???

              Maybe a lifter is not adjusted enough to the middle of the hydraulic lifter range resulting in too much lash?
               
            • halfafish

              halfafish Damn those rabbits, and their holes! FABO Gold Member

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              Solid lifters folks. It's a juice engine but I swapped in a solid valve train.
               
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              • halfafish

                halfafish Damn those rabbits, and their holes! FABO Gold Member

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                I will be busy checking the rest of these suggestions.
                 
              • RustyRatRod

                RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                Then you have to have swapped the head, right?
                 
              • volaredon

                volaredon Well-Known Member

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                No he wouldn't have had to swap the head/ just the rockers and pushrods. The hydraulic lifter head doesn't care,
                I forget what it is about the back bolt on the rocker shaft but something is different about that from a hydraulic lifter engine to a solid lifter engine. One has a regular bolt and the other has a shoulder bolt.
                That said I cracked a head on my dad's 82 Gran fury /6 years ago. I put what I had laying around on that motor to get it rolling, which happens to have been a 63 head complete with drool tubes. I ran the original Hydraulic setup and I remember I had to drill out the bottom of the hydraulic lifter shaft, the top side was ok as was, drilled out the hole on the bottom of the shaft to match the diameter of the hole in the top of the rocker shaft and then all was good.
                 
              • Swingin Chrome

                Swingin Chrome Well-Known Member

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                Dust shield/inspection cover rubbing on flywheel?RJ
                 
              • halfafish

                halfafish Damn those rabbits, and their holes! FABO Gold Member

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                Nope. Like volaredon said, I swapped the solid stuff into the juice head.
                 
              • RustyRatRod

                RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                I was not aware you could do that.
                 
              • halfafish

                halfafish Damn those rabbits, and their holes! FABO Gold Member

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                Yup. Works fine.
                 
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  Does it? Why are you here again?
                   
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                  • halfafish

                    halfafish Damn those rabbits, and their holes! FABO Gold Member

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                    Haha. To be more precise, the valve gear swap works fine. The rest of this is still a mystery. I'm off to eliminate possibilities for a while.
                     
                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                    I think the two heads oil differently somehow. I don't know for sure....something just sticks out in my mind about it.
                     
                  • RustyRatRod

                    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  • Charrlie_S

                    Charrlie_S Well-Known Member

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                    If you swap
                    cam, lifter, rocker shaft, rocker arms, and pushrods
                    The whole thing can swap between solid, and hydraulic systems. The only "gotcha" is the rear rocker shaft bolt. Need to use the correct bolt for the head (changed sometime in the '70's). As stated by Volaredon, some times it is necessary to enlarge the lower rear shaft bolt hole (when using a late shaft on a early head)
                    The difference in oiling, is the cam, itself. The hydraulic cams have a groove around the rear cam journal (not the bearing). The solid lifter cams just have two intersecting oil holes in the rear cam journal.
                    PS: Some aftermarket solid cams are being ground on hydro blanks and have the oiling groove. I always groove the rear journal on solid cams, in my engines. If I wind up with too much oil up top, I can always put a restrictor, in the oil passage in the rear rocker stand
                     
                    Last edited: Dec 19, 2021
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                    • halfafish

                      halfafish Damn those rabbits, and their holes! FABO Gold Member

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                      I know one head has a rear bolt that is stepped, the other is a plain bolt. My 82 truck FSM clearly shows the stepped bolt for the rear of the rocker shaft.

                      20211219_174355.jpg
                       
                    • Charrlie_S

                      Charrlie_S Well-Known Member

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                      The stepped bolt was introducted sometime in the mid '70's. Originally the rocker shaft had a small flat ground into the top front of the shaft, to indicate proper installation. The stepped bolt and revised hole (top larger dia, lower smaller dia), was to make installation "idiot proof".
                       
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