Announcement

Collapse
No announcement yet.

should pistons be moveable by hand around the cylinder?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • should pistons be moveable by hand around the cylinder?

    I had exhaust smoke coming out of the breather pipe of the rocker cover to the air intake pipe. Presumed it was the head gasket. Took the head off, and I can't see any signs of anything wrong, no cracks in the head etc.
    I was inspecting the pistons and noticed that they are all moveable in the bore when at the top of their stroke. Is this normal. Could the smoke be blowing past the rings? The rings are allegedly new.

  • #2
    There has to be some play between pistons and bore and the rings are there to prevent compression passing but normally you would struggle to feel any play by hand, I also have excessive back pressure to the the point of blowing oil out of the front cam seal housing gasket but no smoke from breather, my engine (2LT-E) has 380000 mile and having done a compression test is still within limits, bit late now but maybe that should have been your first check. Do you know why it was re-ringed?

    Comment


    • #3
      Sorry for the late reply. it was rebuilt with new components, for the reason it was in bits anyway.

      Comment


      • #4
        Originally posted by Trebor View Post
        Sorry for the late reply. it was rebuilt with new components, for the reason it was in bits anyway.
        You couldn't have done a compression check anyway then, perhaps now though?

        Comment


        • #5
          I will be doing one now!

          Comment


          • #6
            When you say you can move the piston around the bore, what do you mean? Im guessing you can push the piston from side to side? If so this in its self is not unusual, as you have to have clearance between the piston and the cylinder wall, also bear in mind this will look more than it actually is because the piston lands at the top of the piston are usually a smaller diameter that the skirt. Being a diesel it will have more clearance than a petrol. Like Misled said a compression test is the first port of call, sadly new rings don't always remedy smoking, & excessive blow by, as the piston rings can actually wear the grooves in the pistons over time. The other thing I've seen is where new rings have been fitted, and the bores have not been sufficiently honed, which allows the new rings to "Bed" into the bores .This may require an engine strip down and assessment.

            Comment


            • #7
              I concur with BillaBob, however depending on the outcome of said compression test and before another major strip try and do a "Leak Down" test as you may have other issues especially in the valve clearance area.

              Comment


              • #8
                Very True Misled! I totally overlooked valve issues! Agreed a Leak Down test is the way to go, then if it is a valve issue, its a whole lot less work than a total strip down.

                Comment

                Working...
                X