Triumph Thunderbird. Poss Head Gasket Problem

Discussion in 'Technical Help' started by Robe, May 6, 2021.

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  1. Robe

    Robe New Member

    Apr 24, 2021
    2
    3
    Pembroke, Pembrokeshire
    Hi
    Apologies i put this in wrong place originally as new to this forum and triumph motorcycles.
    Just took delivery of bike sold by po as a project but mechanically solid.
    Started ok first press but will only run on choke even when warm and any blip of throttle engine bogs and will stall unless quick on the choke. When running engine is smooth and no misfire at all. Figured this meant a carb jet clean so they are out and ready to dismantle.
    Whilst doing this found the coolant tank empty. Difficult to see from outside but looked dry as far as I could tell inside. Worried about head gasket now but wanted a bit of advice on best way forward to test before going straight in with taking head off etc . Lots of other things on bike will need advice on but this is the major issue and only 4 days into ownership !
    Any help greatly appreciated. Bw. Rob
    Update- topped up rad and system took about 1.5 litres . Oil looks OK in window. Plan is to clean carbs and run up to temp gently and keep a close eye on what happens to cooling system and exhaust smoke. .any help or advice much appreciated. Bw Rob
     
    • Agree Agree x 1
  2. capt

    capt Elite Member

    May 8, 2016
    2,432
    750
    western Australia
    My trident 94' only took about that 1.5 to 1.8 litres to fill from empty !
    You might have done some damage running so low on coolant !
     
  3. Tricky-Dicky

    Tricky-Dicky Crème de la Crème

    Dec 12, 2016
    2,459
    1,000
    Norfolk UK
    A carb rebuild and clean sounds in order, also agree about the lack of coolant i would suggest once you have it running OK run a sniffer test on the coolant this will tell you if there is a head gasket problem.
     
    • Agree Agree x 1
  4. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,106
    800
    California - USA
    I somehow do not think you have a head gasket issue. Runs and idles normal. No water in the oil. Running the coolant dry is certainly not a good thing to do, but those engines are also pretty tough. I DO suspect you might have some cracked carb boots though. Might want to check them out. ...J.D.
     
  5. Robe

    Robe New Member

    Apr 24, 2021
    2
    3
    Pembroke, Pembrokeshire
    Thanks all for comments. Put carbs back on bike and ran for full 10 mins. No smoke from exhaust or water leaks etc. So looks like head gasket ok.
    Tickover without choke still an issue but think this just needs adjustment.
    Next query is how long before fan should start if bike is ticking over. Appreciate depends on outside temp but wanted to know if fan operating correctly.
    Thanks again. Rob
     
  6. Helmut Visor

    Helmut Visor Only dead fish go with the flow
    Subscriber

    Oct 3, 2018
    3,641
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    Three Counties
  7. Wire-Wheels

    Wire-Wheels Elite Member

    Apr 26, 2019
    2,106
    800
    California - USA
    #7 Wire-Wheels, May 27, 2021
    Last edited: May 27, 2021
    I use a non-contact [infrared] thermometer pointed at the upper radiator tank. It is usually just below boiling. Outside air temp DOES affect the TIME it takes. The real issue is coolant temp RETURNING to the radiator. The T-stat should be open [check upper hose. Too hot to touch]. ...J.D.
     
  8. Robe

    Robe New Member

    Apr 24, 2021
    2
    3
    Pembroke, Pembrokeshire
    Update to last item.
    Carburettors cleaned and bike runs well. May need v slight adjustment for tickover but that's all.
    Anyway as noted have been running bike for 10 mins at a time and no cookant leak . I have replaced fan as was not working and have tested the circuit to it and it operates when I connect the two wires going into the thermostat housing.
    But so far I don't seem to get the fan working. I am not sure if bike is hot enough for fan to start or the switch in the housing is faulty. Not helped as I know the water temp warning bulb is not working.
    Does anyone know how long at tickover before fan kicks in. I am not getting any water leaks at all at radiator cap or expansion tank. Looking into radiator when running no evidence of bubbles so think head gasket is ok .
    Appreciate any advice. Thanks Rob
     
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