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  1. #1
    Join Date
    Jul 2012
    Location
    Little Rock, Arkansas
    Posts
    22

    Default Compression check?

    Does anyone happen to know the correct pressure range for checking compression on a 350 indmar assault? Had my muffler blow up on me and wanted to make sure i didnt blow out any piston rings. Thanks guys!
    Goose
    -2002 Mobius LSV 350 indmar assault FI

  2. #2
    Join Date
    Jan 2008
    Location
    Tallahassee, FL
    Posts
    11,075

    Default

    You don't actually need a figure. Just measure all of them. They should all be within about 10% of each other. If you have one that's 40% different or something like that you have a problem.
    My Mom said I'm not allowed to get wet!
    2008 LSV
    2000 Outback LS (sold)
    Exile Tunes
    PWI
    LLTR!!!!!!!!



  3. #3
    Join Date
    Oct 2010
    Location
    Winnipeg, Manitoba
    Posts
    362

    Default

    I don't know the specs but, if memory serves, I did a compression test on my 2003 outback a couple of years ago and I think the reading was about 195 lb/sq in. across the board. They were all within 2 or 3 pounds of each other. I didn't dig any deeper than that as the motor was running fine anyways.

    If you blew some rings, I would suspect one or two cylinders will be way off.
    past---------------2003 Outback SOLD
    present------------2006 Supra Launch 21V
    possible future-----2013 Mojo

    Ron

  4. #4
    Join Date
    Jul 2012
    Location
    Little Rock, Arkansas
    Posts
    22

    Default

    Awesome thanks guys. I was just searching the interwebs and i found a indmar manual and its saying nothing less than 100psi. And as you said kane, they should be within 10%.

    Thanks very much guys. Ill repost if i find anything off.
    Goose
    -2002 Mobius LSV 350 indmar assault FI

  5. #5
    Join Date
    Jan 2008
    Location
    Pensacola, FL
    Posts
    1,537

    Default

    Within 10% of each other and you will usually find the lower readings on the rear cylinders. I would be concerned if the average was much less than 125. At 100, you are starting to lose a bit of power from the engine in blow by.
    1997 MasterCraft 205

    2008 Moomba Outback
    1999 MasterCraft Sportstar OB
    1992 MasterCraft 205
    1999 Malibu Response LX
    1987 Marlin Magnum Skier

  6. #6
    Join Date
    Jul 2012
    Location
    Little Rock, Arkansas
    Posts
    22

    Default

    Alright awesome. So basically as long as the average pressure is above 125 and they are all within 10% of each other i should be good?
    Goose
    -2002 Mobius LSV 350 indmar assault FI

  7. #7
    Join Date
    Jan 2008
    Location
    Tallahassee, FL
    Posts
    11,075

    Default

    I would not sweat too much if I was consistently 118 or so across the board either. Not all compression testers are created equal. You are looking for a bad cylinder not a weak engine here.
    My Mom said I'm not allowed to get wet!
    2008 LSV
    2000 Outback LS (sold)
    Exile Tunes
    PWI
    LLTR!!!!!!!!



  8. #8
    Join Date
    Jan 2013
    Location
    PA
    Posts
    78

    Default

    I bought a 07 OBV and had the compression checked before I bought it and it was between 180 - 185 accross all cylinders...
    2007 Moomba Outback V

  9. #9
    Join Date
    Jul 2012
    Location
    Little Rock, Arkansas
    Posts
    22

    Default

    Yea i did the check this morning and the lowest i got was 120 and the highest i got was about 150. Im thinking itll be alright. And according to the indmar manual its saying the minimun psi is 100 and the lowest recorded pressure should not be anymore than 70% less than the highest recorded psi.

    Thanks for all the input guys. ill let yall know how she runs tomorrow.
    Goose
    -2002 Mobius LSV 350 indmar assault FI

  10. #10
    Join Date
    Jan 2008
    Location
    Pensacola, FL
    Posts
    1,537

    Default

    Cool, good luck.
    1997 MasterCraft 205

    2008 Moomba Outback
    1999 MasterCraft Sportstar OB
    1992 MasterCraft 205
    1999 Malibu Response LX
    1987 Marlin Magnum Skier

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