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Thread: Unexpected oil leak from GS450 head

  1. #1
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    Default Unexpected oil leak from GS450 head

    Hi All,


    Running my head into a wall hereÖ


    I have finished putting together a GS450 engine and found a leak coming from the head gasket. So I re-did the top, new gasket made sure the surfaces were clean and true, and I was also really careful with tightening the head nuts in a criss-cross pattern to the right torque specs. Although I havenít given it the 2nd round of torque (will do so when Iím back from work).


    Did a quick run up and down a short street (250 meters) and to my horror it still leaks!


    I did a closer inspection and even though I find oil around the head gasket, I now see that the oil might very well be coming from something above the head gasket. Please see the image where the oil pools.


    Where could that be coming from? The head nut seems dry and free from oil. Is there a channel there? What does that #4 bolt do? Could it be coming from that?

    -----------
    GS450E 1985
    Wroom Wroom Wroom!

  2. #2
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    I think the bolt seals the passageway from the stud cavity oil passage to the cam bearing and the valve buckets. If that isn't the source of the leak it could be a crack or porosity in the head. Unlike the roller bearing motors, the oil pressure is about 50 psi rather than 5 or whatever. There are oil jets that reduce the flow/pressure down at the base gasket level that you don't want to leave out.

    I'll take a look at my spare head and see what it otherwise could be.
    Last edited by John Park; 11-24-2020 at 07:14 PM.
    '82 GS450T

  3. #3
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    The bolt should have a rubberized washer under it. I can't see how that area would ever crack as there's nothing happening there. Swap the bolt and washer from the other side over and if the leak moves with it the bolt could be bent or the washer needs replacement. I think the one that goes on the cam chain locknut would be similar or the same.
    '82 GS450T

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    Quote Originally Posted by John Park View Post
    The bolt should have a rubberized washer under it. I can't see how that area would ever crack as there's nothing happening there. Swap the bolt and washer from the other side over and if the leak moves with it the bolt could be bent or the washer needs replacement. I think the one that goes on the cam chain locknut would be similar or the same.
    Aha! Then that could very well be the culprit! Yesterday I checked the bolt and it wasn't all the way tight. It had a full revolution more before it became tight. The washer also looks hard and almost white. Will check if tightening it helps and for now I think I have some nylon washers that could do the trick.

    Will keep you posted.
    -----------
    GS450E 1985
    Wroom Wroom Wroom!

  5. #5
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    OK, it wasn't the bolt as I put in a new washer and made sure it sits tight. Did another test ride up and down the street, and this is how it looks. Maybe there is a crack somewhere and I have missed it, or it wasn't 100% straight? I'm running out of ideas of where to check.

    -----------
    GS450E 1985
    Wroom Wroom Wroom!

  6. #6
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    You need to spot exactly where it's coming from the instant it starts to seep.

    Clean and dry the engine thoroughly, then spray that whole area with a thick coat of cheap foot powder from a spray can. I assume you have people with itchy feet in Denmark...

    Start the engine and watch. You should spot the leak point almost instantly as it wets the powder.

    Let the engine cool and wash off the foot powder -- it's kinda stinky.
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    Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

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    Quote Originally Posted by bwringer View Post
    You need to spot exactly where it's coming from the instant it starts to seep.

    Clean and dry the engine thoroughly, then spray that whole area with a thick coat of cheap foot powder from a spray can. I assume you have people with itchy feet in Denmark...

    Start the engine and watch. You should spot the leak point almost instantly as it wets the powder.

    Let the engine cool and wash off the foot powder -- it's kinda stinky.
    We Danes do have itchy feet, so I'll collect some of that powder and give it a go.
    -----------
    GS450E 1985
    Wroom Wroom Wroom!

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    Quote Originally Posted by bwringer View Post
    You need to spot exactly where it's coming from the instant it starts to seep.

    Clean and dry the engine thoroughly, then spray that whole area with a thick coat of cheap foot powder from a spray can. I assume you have people with itchy feet in Denmark...

    Start the engine and watch. You should spot the leak point almost instantly as it wets the powder.

    Let the engine cool and wash off the foot powder -- it's kinda stinky.
    Alright, I'm getting closer. I might have found out what it could have been. The tach-drive was not tight and even though I tightened it there still is a drop coming off it. I could suspect that it was coming from here and the air-flow would then distribute the oil backwards making it look like it's coming from the head gasket or elsewhere. Will have to do some more driving up and down the street and check if that was it.

    On the left picture the tach-drive with some oil on the bolt area, and on the right the head-gasket. Although the powder has become a bit moist, I suspect that being from oil residue from last time.
    -----------
    GS450E 1985
    Wroom Wroom Wroom!

  9. #9
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    The rev-counter drive is a favourite leak spot.
    A tiny little seal and an o-ring live inside it.
    Be prepared to gasp in surprise at how much they cost for the size of them.
    One tip; carefully examine the shaft of the drive for a wear ridge where the old seal (and road grit) wore a nasty ring in it. No new seal will last very long on a damaged shaft.
    ---- Dave
    79 GS850N - Might be a trike soon.
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    79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
    92 XJ900F - Fairly Stock, for now.

    Only a dog knows why a motorcyclist sticks his head out of a car window

  10. #10
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    Or get the whole taco assembly for £13
    https://www.mandp.co.uk/products/suz...-467999-678288
    The big guy up there rides a Suzuki (this I know)
    1981 gs850gx

    1999 RF900
    past bikes. RF900
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