Announcement

Collapse

Get more Tips, Specs and Technical Data!

Did you know... this Forum is a service of the Studebaker Drivers Club? For more technical tips, specifications, history and tech data, visit the Tech Tips page at the SDC Homepage: www.studebakerdriversclub.com/tips.asp
See more
See less

engine knocking sound

Collapse
This topic is closed.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • engine knocking sound

    I recently purchased a nice '57 Silver Hawk with about 5000 miles on the restoration. After it is warmed up, there is a distinct knocking sound that keeps pace with the RPMs. Doesn't have that lifter type sound. What are the likely causes?

  • #2
    There's the off chance it's the fuel pump. There's a chance it's a flex plate going bad (is it an automatic?) - but it's it's a dull knocking sound, it might be a connecting rod bearing OR a broken piston. What's the oil pressure look like at speed? Has it changed of late?[}]

    Miscreant at large.

    1957 Transtar 1/2ton
    1960 Larkvertible V8
    1958 Provincial wagon
    1953 Commander coupe
    1957 President 2-dr
    1955 President State
    1951 Champion Biz cpe
    1963 Daytona project FS
    No deceptive flags to prove I'm patriotic - no biblical BS to impress - just ME and Studebakers - as it should be.

    Comment


    • #3
      It has a new fuel pump. It's automatic. Oil pressure shows 60 when driving, 40 at idle.

      Comment


      • #4
        The symptoms you describe are those of a blown head gasket between the internal cylinders, such as between 1&3 or 3&5 or 2&4 or 4&6. What sounds like a knock is the hot gas going from one cylinder to the adjoining one. Oil pressure will stay OK, as long as you don't breech an oil passage and you won't see any coolant in the oil or oil in the coolant. Get a cheapo stethescope and listen between the cylinders on both heads to determine which side it is on, and which cylinders are affected. All that should be required if you get to it right away is a new head gasket (check for flatness before you reassemble). If you let it go too long, you will be looking at doing both heads and probably planing them both as well.

        Comment


        • #5
          whacker - what you say may be true. But you'd think he'd be telling us that this thing is running rough if that were the case.[}]

          Bing, can you run a compression check? [?]

          Miscreant at large.

          1957 Transtar 1/2ton
          1960 Larkvertible V8
          1958 Provincial wagon
          1953 Commander coupe
          1957 President 2-dr
          1955 President State
          1951 Champion Biz cpe
          1963 Daytona project FS
          No deceptive flags to prove I'm patriotic - no biblical BS to impress - just ME and Studebakers - as it should be.

          Comment


          • #6
            I think Mr Biggs is right in that a blown head gasket usually results in a vehicle running roughly. This thing is VERY smooth. Yes, I can do a compression check. What might the results tell me?

            Comment


            • #7
              No, this kind of blown gasket doesn't cause the engine to run rough. It will cause it to burn oil tho. All the gas is still kept within the heads and cylinders. It is usually caused by not re-torqueing the head bolts, or not torqueing them enough, or not getting sealing compound between the leaking cylinders. A compression test will definatly determine if I am right. You will find two cylinders next to each other with very low, but equal compression.

              Comment


              • #8
                I've been thinking about this, and the possibility exsists that I could be wrong (hard to believe, I know). Let's look at this logically. Here are the clues we have: engine has a recent (5000 mi) rebuild. Sound (knock) occurs after warm up. Sound keeps pace with engine RPMs. Doesn't sound like typical lifter noise. Oil pressure is good and stays good. Here are the assumptions: engine doesn't seem to loose power. Engine isn't overheating. Gas consumption is normal. Not a noticable vibration.

                OK. The sound must be engine related, so we eliminate brakes, U-joints, transmission, other running gear. What happens when the engine warms up? The thermostat opens. The oil, if it is single viscosity, thins out, if it is multi-vis it thickens. The rubber belts stretch.
                Just because it dosn't have the typical lifter sound doesn't mean it isn't the lifters - it could still be the lifters.
                It could be that the water pump or the fan flexes or rotates off center when the thermostat opens.
                It could be that the distributor has worn bearings that allows it to tap when the oil thins.
                It could be the generator is loose on the bracket and rattles when the belts expand.

                It could also be a blown head gasket between two adjacent cylinders.

                Comment


                • #9
                  Good enough. I will do the compression check tomorrow and post the results.

                  Comment


                  • #10
                    My engine mechanical knowledge isn't that great, but why could it not be a rod bearing? I know that sound can go away when under load, but it would increase with rpm--right?[:I]

                    ________________________
                    Mark Anderson
                    http://home.alltel.net/anderm
                    1965 Studebaker Cruiser

                    Comment


                    • #11
                      check the torque converter bolts and engine oil level, then drive it until it blows up and the issue will self identify, you guys are too serious, just enjoy! this is a hobby, remember? the damn thing may last forever!

                      Comment

                      Working...
                      X