Click for Westport Click for Ocean Alexander Click for Cross Click for Burger Click for Glendinning

Compression question

Discussion in 'Technical Discussion' started by lanaperkins, Jun 29, 2011.

You need to be registered and signed in to view this content.
  1. lanaperkins, Jun 29, 2011
    #1
    lanaperkins

    lanaperkins New Member

    Joined:
    Jun 28, 2011
    Messages:
    3
    Location:
    United States
    I am noticing a valve train/upper end noise from the port engine. Starboard engine had similar noise, not as loud, that came and went with test run. Had a compression test run on starboard engine.

    Cyl.#1:190 Cyl.#2:100
    Cyl.#1:195 Cyl.#2:190
    Cyl.#1:195 Cyl.#2:190
    Cyl.#1:175 Cyl.#2:190

    Can anyone offer info regarding source of noise and low compression? :(
  2. dennismc, Jun 29, 2011
    #2
    dennismc

    dennismc Senior Member

    Joined:
    Jan 29, 2009
    Messages:
    1,177
    Location:
    Vancouver BC
    Compression

    Possibly rings and wrist pin problem
  3. Capt J, Jun 30, 2011
    #3
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,530
    Location:
    Fort Lauderdale
    What kind of engine are we talking about here? It could be piston rings, however if you're hearing an upper valvetrain noise, it could be something easier to fix such as a bent valve, a bad lifter, broken rocker arm, bent pushrod or more. Taking the valve cover off and looking inside might help rule out a few things, but it could be any number of things
  4. Marmot, Jun 30, 2011
    #4
    Marmot

    Marmot Senior Member

    Joined:
    May 20, 2007
    Messages:
    3,311
    Location:
    9114 S. Central Ave
    Do you have 4 2-cylinder engines, 2 4-cylinder engines and don't know how to number the cylinders, or a V-8 and don't know how to number the cylinders?

    In any event, you appear to have one cylinder with low compression that is probably (since you mentioned noise coming from the top end) related to a valve problem. Do a leakdown test and listen for air hissing out where it shouldn't.

    The engine manufacturer will tell you maximum variation allowed between cylinders. That fourth #1 with the 175 may or may not have a problem depending on how accurate that reading is and how the readings were taken and if any attempt was made to improve it. It may well be within specs but since there is more information missing than present it really can't be analyzed over the internet.
  5. K1W1, Jun 30, 2011
    #5
    K1W1

    K1W1 Senior Member

    Joined:
    Sep 30, 2005
    Messages:
    7,427
    Location:
    My Office

    It might be a Doxford :D
  6. Marmot, Jun 30, 2011
    #6
    Marmot

    Marmot Senior Member

    Joined:
    May 20, 2007
    Messages:
    3,311
    Location:
    9114 S. Central Ave
    Then he would have more pistons than cylinders and the top end would be a lot quieter!
  7. oceanborn, Jun 30, 2011
    #7
    oceanborn

    oceanborn New Member

    Joined:
    Apr 9, 2011
    Messages:
    1
    Location:
    caribbean
    You should check also valve clearance of the lowest compression cylinder. possiblity rockerarm bolts might be loosen. Wrong adjusted valve clearance may cause noise too.
  8. Marmot, Jul 1, 2011
    #8
    Marmot

    Marmot Senior Member

    Joined:
    May 20, 2007
    Messages:
    3,311
    Location:
    9114 S. Central Ave
    These questions might be on the test ...

    If the bolts holding a rocker arm become loose, what is the effect on that valve?

    If tappet clearance becomes large enough to create noise, what effect does that have on the valve?

    If an engine has a noisy valve train at startup but that noise stops shortly afterwards, what is the usual suspect?

    If a gas engine makes a rattling noise like pebbles in a can that comes and goes with load variations what might be the cause? What might be the long and short term results of this condition?