Thunderbird 900 Spitting Out Its Coolant

Discussion in 'Technical Help' started by Stu9000, Jun 22, 2024.

  1. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
    2,391
    1,000
    Lancashire
    I know some are a little confused re my post regarding the pressurised air test, so to clarify during this test, compressed air is introduced into the cylinder, and the escape path of the air is monitored. Air escaping through the intake or exhaust indicates leaking valves. A blown gasket often results in adjacent cylinders having low pressure. As a time served mechanic in my early days I often used this equipment for both 2 and 4 wheel machines, the system I had back in the day was a sun diagnostic and test unit, as equipment advanced it became viable to purchase basic kit to do the work. I have attached a link that details how it works, there is no rocket science in using this method and you can't damage the engine internals. Hope this explains things more clearly. The attached picture shows the very same unit I used.

    How To: Cylinder Leak Down Test - Owners World

    R.jpg
     
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  2. Stu9000

    Stu9000 Active Member

    Nov 4, 2021
    104
    33
    Kingston-upon-thames
    Drained the oil today. It was definitely due for a change but not the creamy emulsion I feared. When I took the cap off the other day it has emulsified oil in it. I assumed the worst. Now I am not so sure.

    I am getting grey smoke at start up.
    The oil is not emulsified.
    I was getting over heating issues but not now.
    The plugs used to foul with black sooty deposits, but not now.

    Replacing the coil packs has definitely helped.

    I will see how she runs over the next few days.
     
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  3. Bolosun

    Bolosun Well-Known Member

    Aug 25, 2020
    236
    93
    Crewe/Cheshire
    I assume the air filter is clean and there is no oil in the air box? Not to familiar with your bike but assume it has crank case breathers etc. Have you checked them for blockages and splits?
     
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  4. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
    2,391
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    #64 Iceman, Dec 7, 2024
    Last edited: Dec 8, 2024
    Grey smoke is an indicator for a possible head gasket failure, however if this only takes place on warm up that leans me towards something else. Can you clarify how and were you store the bike, it would be helpful. By that I mean outside or in a garage, is the garage concrete panelled, as mentioned it does make a difference.
     
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  5. Stu9000

    Stu9000 Active Member

    Nov 4, 2021
    104
    33
    Kingston-upon-thames
    New air filter fitted recently. When I replaced it there was some emulsified oil that had made it way into the airbox via the breather hose. Maybe two table spoons worth. I've not checked it since it all went back in but no sign of oil oozing out..

    Interesting you should mention the Crank case breather hose. It was a bit ropey. I wanted to replace it but it seems jammed behind the starter motor so I just taped it up a small split. Maybe I should run a fresh hose with a small pod on top, or I even read people just feed to a small plastic bottle, which would allow me to see if it was oozing out gunge. 20241209_230923.jpg

    Bike is running better but was hard starting after a couple of days. Not much smoke ATM. Not over heating. Put three new plugs in today. The old ones were not sooty like I have posted earlier in this thread. Seems to start a lot better. She is popping a fair bit on the over run, which she always has, and there bikes are known for it. Maybe she is running rich, but the plugs were not badly sorted up.
    It's not clear that it is gasket failure either. Coolent water level is not going down. Not much smoke from exhaust. Ill keep an eye on the oil. So... Basically I'm still confused.
     
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  6. Bolosun

    Bolosun Well-Known Member

    Aug 25, 2020
    236
    93
    Crewe/Cheshire
    #66 Bolosun, Dec 10, 2024
    Last edited: Dec 10, 2024
    I would definitely replace the hose.
     
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  7. Stu9000

    Stu9000 Active Member

    Nov 4, 2021
    104
    33
    Kingston-upon-thames
    Bike is stored outside , in a tent basically. Pram hood storm shelter type arrangement. I do ride her in the winter but not as much. Maybe every three weeks. Much more recently, because the car had a timing chain failure. Don't even ask. Bike still starting much better. Does not sound quite right and, very occasionally, stalls for no obvious reason. I'm going to change the oil again this weekend, check fluids and have a look at the plugs.
     
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  8. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    Ah I was wondering if this was the case re storage, what can happen is a machine outside is subject to a lot of internal condensation, inside the exhaust, on start up the heat turns the condensation to vapour, basically smoke.
     
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  9. Stu9000

    Stu9000 Active Member

    Nov 4, 2021
    104
    33
    Kingston-upon-thames
    Changed the oil again today. Last did this 2 weeks ago. Completely emulsified! I would say "gasket failure".
    But if I turn over the engine with the coolant cap off, it does not sploosh water out. This suggests there is no failure between combustion chamber and water jackets.

    Couple of questions.
    Is it conceivable that there is a leak between the coolant and oil, but not the combustion chamber?
    What else, other than gasket failure, could cause oil to become emulsified?

    Thanks

    S
     
  10. Bolosun

    Bolosun Well-Known Member

    Aug 25, 2020
    236
    93
    Crewe/Cheshire
    Have you changed the pipe with the split in it?
     
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  11. Stu9000

    Stu9000 Active Member

    Nov 4, 2021
    104
    33
    Kingston-upon-thames
    Yes. I've replaced it. Pipe just vents to air, rather than the box. It's transparent so I can see if gung is exiting the crankcase. Nothing so far.
     
  12. Stu9000

    Stu9000 Active Member

    Nov 4, 2021
    104
    33
    Kingston-upon-thames
    Yes. I've replaced it. Pipe just vents to air, rather than the box. It's transparent so I can see if gung is exiting the crankcase. Nothing so far.
     
  13. Stu9000

    Stu9000 Active Member

    Nov 4, 2021
    104
    33
    Kingston-upon-thames
    Coolant level has not dropped either so I am very confused as to where water is getting into the oil.
     
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