Oil leak rear cylinder base gasket.

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by DirtyADV, Sep 14, 2012.

  1. DirtyADV

    DirtyADV Long timer

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    Since I dont know how or if its even possible to change title of a thread Im starting a new one, had one about my oil leak, was worried it was pushing oil out of the engine case.

    Luckily that dont seem to be the case, probably just some oil/degreaser finding its way under the paint through a crack.

    But have for sure a leak from the rear cylinder base gasket.

    This was after like 5 kilometer of driving:

    <a href="http://www.flickr.com/photos/dirtyadv/7973213312/" title="Right side rear cylinder base by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8039/7973213312_4af5d97914_z.jpg" width="640" height="428" alt="Right side rear cylinder base"></a>

    Nothing could be seen at the left side at that point (well a little down by the clutch slave but that doesnt worry me much).

    But after like 10 kilometers the left side looked like this:

    <a href="http://www.flickr.com/photos/dirtyadv/7983894235/" title="Rear cylinder by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8456/7983894235_242330367c_z.jpg" width="640" height="480" alt="Rear cylinder"></a>

    And the right side like this after 10 km:

    <a href="http://www.flickr.com/photos/dirtyadv/7983899158/" title="Rear cylinder by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8177/7983899158_f6e4003fd8_z.jpg" width="640" height="480" alt="Rear cylinder"></a>

    Have started stripping the bike and had a plan to add silicon for now and see if that could seal it up but after stripping and getting a better look it seem to leak from 2 places, Seems to be a no leak area marked in blue and on the sides there is oil marked red.

    <a href="http://www.flickr.com/photos/dirtyadv/7986507664/" title="Rear cylinder drawn on by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8457/7986507664_dac92e6e37_z.jpg" width="640" height="480" alt="Rear cylinder drawn on"></a>

    Also talked to a friend and we started talking about crankcase pressure and my goldfish brain started remembering something about a crank case valve and have this on my crankcase breather hose:

    <a href="http://www.flickr.com/photos/dirtyadv/7986499116/" title="Crankcase breather valve? by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8456/7986499116_6567ab3f75_z.jpg" width="640" height="480" alt="Crankcase breather valve?"></a>

    Could this cause a to high crankcase pressure?


    Can the cylinder be lifted without having trouble with the cylinder head gasket? If so I think ill go ahead and order a new base gasket and simply lift the rear and see what it looks like and change that gasket.

    Bike is stripped down to this right now and a few more electrical wire and I think the engine should be possible to tilt down, was planning to leave oil tank and radiator in place, just loosen 2 top bolts on rad ...anyone tried this?

    <a href="http://www.flickr.com/photos/dirtyadv/7986491171/" title="Apart by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8445/7986491171_deda9dea71_z.jpg" width="640" height="480" alt="Apart"></a>

    Any help appreciated!

    Cheers!

    /Johan
    #1
  2. booger1

    booger1 Been here awhile

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    I thought I had this problem once before, but before panic set in, I made a few calls. Ended up being that the float hight was off on the rear carb, it was leaking fuel down over the grime and right on the base gasket of the rear cylinder. Check this first before going on.
    #2
  3. kamanya

    kamanya Andrew to most

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    Before you do anything drastic check all the other culprits, maybe oil pressure sensor?

    But if you have to, I'm sure you cannot get the rear head off with the engine still in the frame. Front yes, rear no.
    #3
  4. DirtyADV

    DirtyADV Long timer

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    Feels like oil and no fuel smell and fuel should evaporate after a while, but have some talcum powder to see better would that cause fuel to stay?

    Had a fuel leak in the beginning of the summer but then it came out of the drain hose from the air box. Also have the overflow hoses extended all the way down so it wont dump fuel between the cylinders.

    So cant see how any fuel could end up between the cylinder on my bike. And should any fuel find its way out of the airbox there should be signs higher up on the cylinder also dry and clean all the way down to the base.

    Glad you are pointing out the easy fixed and I really wish it was an easy one but Im afraid its not.

    Would really like to know what this is on the breather hose, it does not show up on the parts fiche there it just say breather hose:

    <a href="http://www.flickr.com/photos/dirtyadv/7986499116/" title="Crankcase breather valve? by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8456/7986499116_6567ab3f75_z.jpg" width="640" height="480" alt="Crankcase breather valve?"></a>

    And if its possible to lift cylinder and head together and not having to change that gasket?


    /Johan
    #4
  5. DirtyADV

    DirtyADV Long timer

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    Was hoping for the oil pressure sensor but that is not the problem.


    Plan on having the rear engine mount in place but loosen the front end and let it tilt down and then it must be possible to lift the rear cylinder?

    Should that not be the case Ill loosen the rear end also if needed, everything is loose enough apart from the a few electrical wires right now and the top mounts for the radiator.

    /Johan
    #5
  6. charlie264

    charlie264 Long timer

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    I can see what you’re trying to achieve, I have no idea if you can pull the rear cylinder with motor in the bike. But sometimes it’s just easier to remove the motor; you’re going to lose coolant anyway, personally I order a complete gasket kit and do the job properly. I’ve never removed the whole lot, a barrel + head in one go, hoping to save the head gasket..Maybe it’s possible, but would I really trust it not to leak when rebuilt.

    I doubt excessive case pressure is causing oil past the base gasket; any pressure would vent elsewhere and would have to be incredibly high for fail a gasket. I hope it’s just the gasket and not the cavitations thing Pyndon had, he got a new case...I’d be tempted to use a new gasket and silicon sealant to fix until I could source a new motor.
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  7. DirtyADV

    DirtyADV Long timer

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    We will see how it goes, and what the cases look like once Im able to lift the cylinder, had it only seemed to be a central point of oil leak I was going to remove starter motor and seal with silicone but as it looks now Ill try to lift the cylinder and see and swap the base gasket.

    We will see if its smart or stupid.

    Thanks for the help so far!

    /Johan
    #7
  8. StmbtDave

    StmbtDave AKA Invisible Dave

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    I highly doubt it. Without looking at the fische, I would expect that the head bolts extend all the way down to thread into the case. This would hold the head and the cylinder tightly together.

    Even more unlikely. The gasket is a full circle and it obviously won't slide over the cylinder. You would have to cut it to get it around the piston rod and that would totally defeat what you're trying to repair. Lifting it and applying a sealant would be the only option short of pulling the head and cylinder.

    Dave
    #8
  9. DirtyADV

    DirtyADV Long timer

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    Yes the bolts are all the way through both the head and cylinder but there are bolts holding the head and cylinder together as one unit also:

    [​IMG]


    So plan is to lift it up and undo the clip holding the piston pin/rod slide that out and remove cylinder and head complete with the piston, swap gasket and back together depending on how things look.

    /Johan
    #9
  10. DeeGee

    DeeGee I'm a Yorkshireman thanoz

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    I had the same problem on my old 950 and panic set in straight away.

    Pics are pretty similar

    [​IMG]

    [​IMG]

    [​IMG]

    I did the talc test and was sure it was the cylinder :cry

    [​IMG]

    [​IMG]

    But once I stripped it down it was the oil pressure switch. I'm sure that's the culprit that's the issue here, plus the fact that the only other bike I know of which was leaking at the base of the cylinders was Pyndons' 950.

    I hope I'm right :thumb:
    #10
  11. DirtyADV

    DirtyADV Long timer

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    Yours is pretty oily around the front cylinder also, mine is bone dry around the front and the oil pressure switch Im afraid:

    <a href="http://www.flickr.com/photos/dirtyadv/7983897030/" title="Front cylinder by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8303/7983897030_11fc92818b_z.jpg" width="640" height="480" alt="Front cylinder"></a>

    Was hoping for the easy pressure switch but its not.

    /Johan
    #11
  12. FuTAnT

    FuTAnT KTM 990ADV

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    Without going all out, would you not just re-torque the head / cylinders as a first point of call? Or have you already done this?
    #12
  13. DirtyADV

    DirtyADV Long timer

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    Have done that already and torque was correct on all of them.

    /Johan
    #13
  14. Navin

    Navin Long timer

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    How about adding another 5-7 ft-lbs?
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  15. DirtyADV

    DirtyADV Long timer

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    Good thought but Im really close to being able to lift the jug and see how things look and fit a fresh gasket, since it will be possible I plan to also add some heat resistant silicone around the bases of both the front and rear along the base.

    /Johan
    #15
  16. Buscapé

    Buscapé Adventurer

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    Then here's the second one : I had a leaky bottom gasket on the rear cylinder on my 2006 '990. Spooned out the engine, replaced all gaskets (top and bottom) on both cylinders. Problem solved.
    #16
  17. Gustavo.Ramos

    Gustavo.Ramos Been here awhile

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    You can take the heads off w/o taking the motor out. Done that recently, it's pretty much straightforwad.

    Regarding the base gaskets, if the bolts are correctly torqued, you can try to remove them, lift the heads w/o taking them off completly, apply sylicon sealant and put them back down. It may work for 100 miles or 10.000.

    If you have the time and money, take it as an opportunity to take the heads off, clean carbon deposits thoroughly, rotate valves, etc.

    Or try the lift, apply sealant and retorque.
    #17
  18. charlie264

    charlie264 Long timer

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    If you&#8217;ve got a good mating surface you won&#8217;t need any silicon, check the case join for gasket material, case mating compound or silicon there. I use just plain old grease on the new gaskets. Got to remember tolerance on the whole head stack...don&#8217;t know what the tolerances are on the LC8...i.e. no gaskets would the piston strike the head.
    #18
  19. DirtyADV

    DirtyADV Long timer

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    Rear cylinder is lifted.

    Can confirm I have a mild Pyndon Syndrome!

    There is wear on the cases and also a little on the cylinder base.

    Pictures will be added later this evening when I get back home.

    /Johan
    #19
  20. DirtyADV

    DirtyADV Long timer

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    Here are some pictures:

    Around the cam chain tunnel some wear can be seen:

    <a href="http://www.flickr.com/photos/dirtyadv/8000616386/" title="Rear base surface by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8306/8000616386_fb0727d9b9_z.jpg" width="640" height="480" alt="Rear base surface"></a>

    And cylinder base:

    <a href="http://www.flickr.com/photos/dirtyadv/8000615794/" title="Rear base surface by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8439/8000615794_7027f7a816_z.jpg" width="480" height="640" alt="Rear base surface"></a>

    And also some wear on the cylinder:

    <a href="http://www.flickr.com/photos/dirtyadv/8000613685/" title="Gasket removed by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8307/8000613685_3be0672254_z.jpg" width="640" height="480" alt="Gasket removed"></a>

    Better writeup

    So now the question is how much to do about it?

    New gasket and some liquid gasket? Bolt it back up give it some road miles and see if it holds up and then call it a season, winter is around the corner.

    Then rip the front off and do the same (would guess its not far away from leaking). And then add a thick bead of silicone around the bases to keep stuff out.

    Exhaust valve are showing some deposit buildup:

    <a href="http://www.flickr.com/photos/dirtyadv/8000613141/" title="Exhaust valves by DirtyADV, on Flickr"><img src="http://farm9.staticflickr.com/8308/8000613141_4268593355_z.jpg" width="640" height="480" alt="Exhaust valves"></a>

    But is it worth putting to much time and money into this engine? Sealing the bases as best possible and drive the shit out of it until something blows? And then see if its time to get hold of a used engine or maybe an entire new bike, but that would be a decision for later.

    /Johan
    #20