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Thread: 308 Problem

  1. #1
    Newbie Watty73's Avatar
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    Default 308 Problem

    Hi guys and girls,

    Hoping someone can make a few suggestions on tis matter. I have a red 308 fitted in my boat. Only had the boat for around 6mths so o not know a lot of the history on it. Boat w running fine but did have a slight rattle/ping when revs getting up around 3000 or over. As we are only social skiers with the kids we very rarely pushed the motor past 3500 rpm so didn't really notice much. Basically we went skiing on a weekend with no problems, however the following weekend we put the boat in the water and I take it for a short run to warm it up before putting the kids on-board. About 2 mins into a short run I notice smoke from the engine cowl. Open opening up I see light smoke from the breather cap on the rocker cover. As such boat goes back on trailer and home. Once home start mucking around and in that when idling t is fine. When reved over 1500rpm smoke appears. I puled out the breather and notice that what appears to be blowby is quite severe at around 3000rpm. Now confused, if it was worn rings I cannot see how it would have come on so suddenly. Could a blown head gasket into the valley cause this ? Stuck Valve or broken rings ??
    Still starts and runs like dream on low revs..................
    Any ideas.....
    Motor coming out next weekend.....

  2. #2
    Newbie Watty73's Avatar
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    Additionally I believe the motor is stock. I have replaced the carby and fuel pump and plugs only. When I pulled the plugs when it started smoking I noted that the two front plugs at the high end appeared to be a little oily but not extreme by any means. QUOTE]

  3. #3
    Newbie Watty73's Avatar
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    Default 308 Problem in a skiboat

    Hi guys and girls,

    Hoping someone can make a few suggestions on tis matter. I have a red 308fitted in my boat. Only had the boat for around 6mths so o not know a lot ofthe history on it. Boat w running fine but did have a slight rattle/ping whenrevs getting up around 3000 or over. As we are only social skiers with the kidswe very rarely pushed the motor past 3500 rpm so didn't really notice much.Basically we went skiing on a weekend with no problems, however the followingweekend we put the boat in the water and I take it for a short run to warm itup before putting the kids on-board. About 2 mins into a short run I noticesmoke from the engine cowl. Open opening up I see light smoke from the breathercap on the rocker cover. As such boat goes back on trailer and home. Once homestart mucking around and in that when idling t is fine. When reved over 1500rpmsmoke appears. I puled out the breather and notice that what appears to beblowby is quite severe at around 3000rpm. Now confused, if it was worn rings Icannot see how it would have come on so suddenly. Could a blown head gasketinto the valley cause this ? Stuck Valve or broken rings ??
    Still starts and runs like dream on low revs..................
    Any ideas.....
    Motor coming out next weekend.....


    AdditionallyI believe the motor is stock. I have replaced the carby and fuel pump and plugsonly. When I pulled the plugs when it started smoking I noted that the twofront plugs at the high end appeared to be a little oily but not extreme by anymeans.


  4. #4
    been here .......too long Smitty2's Avatar
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    Default

    .. start with the usual
    compression test, leak down and cooling system tests
    __________________________________
    ONE OF THE Aussie V8 MODERATOR/ADMIN TEAM
    Never late in an AussieV8!
    Club circuit racing...the best fun you can have with your pants on

  5. #5
    Do you ever leave?
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    ^^Yup that. Doesn't sound good though. Nothing a rebuild wont fix...

  6. #6
    Do you ever leave? HQ308Ute's Avatar
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    yeah or worn valve guides.. dont mean to be a smartass but there isnt too much oil in it?

  7. #7
    Newbie Watty73's Avatar
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    only 5lts of oil in most recent change. That included with a new filter so estimating 4 1/2 in the sump....
    Nothing taken as being smart as I am chasing help HQ...LOL

  8. #8
    Newbie Watty73's Avatar
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    And on the blowby matter,,,when the breather is taken out and revs brought up to 3000rpm the smoke would be blowing around 300mm high with some force. I cant see how it can be caused from excess oil ???
    If I remove the breather and the PCV valve hose from the opposite bank they both smoke....If I only remove the breather and put my hand over it and let it idle it almost feels like it creates suction until the revs come up.........any suggestions other than to continue pulling the donk out and tearing it down ???
    Last edited by Watty73; 31-10-2016 at 09:10 PM.

  9. #9
    Newbie Watty73's Avatar
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    Pulled the bugger down and found the ringlands broken in cylinder 8......CRAP !!!!!!!
    Engine machinist has looked and identified a pin hole thru the bore from the waterjacket. Appears water gotten between ringlands and wouldn't compress resulting in smashed rings........
    Looks like a new bloke to be sourced.....Anyone with a trimatic pattern 308 short motor I would love to hear from you. Leave a reply or SMS name and details to 0406 427292...

    Cheers,

  10. #10
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    you couldn't just sleave the bore?

  11. #11
    Newbie Watty73's Avatar
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    Yeah,,,,,engine builder has quoted me to sleeve and rebore but he is concerned that the other bores may develop similar issues...

  12. #12
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    I would get another block.

  13. #13
    Newbie Watty73's Avatar
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    304 it is..............struggled to find a decent 308 block.
    New flywheel shroud so engine mounts will fit the Turbo pattern and drop the old 308 heads onto the 304 which eliminates the need for another $1000 on marinising manifolds. Swap the cams over and hopefully will have this back on the water..........
    Rebored out to 20thou over so shouldn't be to far off the 308 horsepower.

  14. #14
    casual poster capri1276's Avatar
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    how many blocks do you need as I have a few?

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