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  1. #1
    Join Date
    Apr 2011
    Location
    Dublin and Alicante.
    Posts
    655

    Default High oil consumption and smokey exhaust.

    I rebuilt my old penta 2002 year before last.
    I goes like clock work and starts after a couple of turns.
    Didn't rebore the cylinders as the ring clearances seemed good.
    Anyway was hoping it would improve when the new rings bedded in but no luck there.
    The oil consumption is about half a litre an hour at 1700 revs.
    I'm thinking of trying 5w 30 oil instead of the 10w 40.
    Any opinions wekcome
    Just here for the Craic!

  2. #2
    Join Date
    Sep 2017
    Posts
    769

    Default Re: High oil consumption and smokey exhaust.

    Quote Originally Posted by Contest1 View Post
    I rebuilt my old penta 2002 year before last.
    I goes like clock work and starts after a couple of turns.
    Didn't rebore the cylinders as the ring clearances seemed good.
    Anyway was hoping it would improve when the new rings bedded in but no luck there.
    The oil consumption is about half a litre an hour at 1700 revs.
    I'm thinking of trying 5w 30 oil instead of the 10w 40.
    Any opinions wekcome
    A thinner oils will be worse why not use 15/40

  3. #3
    Join Date
    Oct 2002
    Location
    Chichester
    Posts
    798

    Default Re: High oil consumption and smokey exhaust.

    If you're thinking that a thicker oil will reduce the oil consumption, then I would suggest you need 20W 50 not 5W 30. Maybe the oil is getting past the valve stems?
    Maybe your engine is suffering from a blocked crankcase breather?

  4. #4
    Join Date
    Apr 2011
    Location
    Dublin and Alicante.
    Posts
    655

    Default Re: High oil consumption and smokey exhaust.

    Quote Originally Posted by Old Harry View Post
    A thinner oils will be worse why not use 15/40
    Thanks. I must admit I got the idea for 5w 30 from an article I read online.
    Obviously not the best source.
    Just here for the Craic!

  5. #5
    Join Date
    Apr 2011
    Location
    Dublin and Alicante.
    Posts
    655

    Default Re: High oil consumption and smokey exhaust.

    Quote Originally Posted by neil_s View Post
    If you're thinking that a thicker oil will reduce the oil consumption, then I would suggest you need 20W 50 not 5W 30. Maybe the oil is getting past the valve stems?
    Maybe your engine is suffering from a blocked crankcase breather?
    Replaced the valve stem seals and pushed a welding rod through the breather port in the head. Seemed to go right into the sump
    Will try the 15w 40 first then maybe the 20w 50.
    Last edited by Contest1; 04-04-19 at 19:08.
    Just here for the Craic!

  6. #6
    Join Date
    Jul 2007
    Location
    Sailing the Aegean
    Posts
    831

    Default Re: High oil consumption and smokey exhaust.

    Quote Originally Posted by Contest1 View Post
    I rebuilt my old penta 2002 year before last.
    I goes like clock work and starts after a couple of turns.
    Didn't rebore the cylinders as the ring clearances seemed good.
    Anyway was hoping it would improve when the new rings bedded in but no luck there.
    The oil consumption is about half a litre an hour at 1700 revs.
    I'm thinking of trying 5w 30 oil instead of the 10w 40.
    Any opinions wekcome
    Did you glaze bust or hone the bores before fitting the new rings?

  7. #7
    Join Date
    May 2007
    Posts
    36,636

    Default Re: High oil consumption and smokey exhaust.

    Half a litre an hour of sump oil is a helluva lot.
    It is seriously near running on burning the sump oil, which is a runaway condition which will rev your engine to destruction.

    If the exhaust is really smokey, then perhaps the oil is going down the valve guide, not getting into the cylinder to fuel the engine.

    One possible thing to look at is, is the top end flooding with oil?
    If yo utake the rocker cover off immediately after running, is ther more oil than there should be?
    Either a blocked drain to the sump, or the rocker feed pouring in too much?

    If the engine is getting up to temperature, then to have a thicker oil at running temp, you want something like a 10w60, but leaving aside the debate about such synth oils, this would be papering over the cracks.
    If the ring gaps were OK, I'd be thinking valve guides slack. Unless the rocker box is just filling with oil. I had this on a car once, a shot cam bearing.

  8. #8
    Join Date
    Dec 2010
    Location
    South Oxfordshire, Gosport and Wellington New Zealand.
    Posts
    7,880

    Default Re: High oil consumption and smokey exhaust.

    I had heavy oil consumption with a 3 cylinder Yanmar. It came filled with a 5/20 modern semi synthetic marine oil and with a spare 4 litre container of same.

    It was all gone by the time we got to Gosport from Watchet, including buying more oil in Falmouth. Little wind, so the donk was on almost all the time.

    Changing to old style 20/50 GTX cured the problem completly.

  9. #9
    Join Date
    Jul 2006
    Location
    Emsworth Hants
    Posts
    12,354

    Default Re: High oil consumption and smokey exhaust.

    Heavy oil use indicates new piston rings are required, as I found.

  10. #10
    Join Date
    Jan 2005
    Location
    West of Scotland
    Posts
    2,983

    Default Re: High oil consumption and smokey exhaust.

    Quote Originally Posted by KellysEye View Post
    Heavy oil use indicates new piston rings are required, as I found.
    It can indicate that - but it is by no means a given conclusion.

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