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  1. #1
    Join Date
    Mar 2004
    Posts
    5,924

    Default External turbo temperature, how to fix a thermocouple on

    Looking at my turbo and others on line, they have these ‘access ports’
    Mine has been in place for some time, could be tough to remove ????

    By the looks of this image, they ‘just’ unscrew, any ideas what tool to use, looks like an Allen key to me

    Unscrew the port, drill a hole into the shoulder and fix an external ring thermocouple ?

    Or you have a better idea ?
    Attached Images Attached Images

  2. #2
    Join Date
    Jun 2011
    Location
    Volos-Athens
    Posts
    4,719

    Default Re: External turbo temperature, how to fix a thermocouple on

    NO

    you don't fit the thermocouple ON the turbo like that!
    you generally fit it before on the exhaust manifold (tough, typically in our applications its liquid cooled...) or after on the riser (if it's not cooled, like I did on mine)
    you could if you're lucky drill on the turbo flange to the exhaust manifold not much space there and you'll have to remove the turbo to do so. Not sure with the heat cycles if you're compromising the cast though. Some more experienced ppl may comment on that.

    V.

  3. #3
    Join Date
    Oct 2003
    Location
    west yorkshire
    Posts
    3,630

    Default Re: External turbo temperature, how to fix a thermocouple on

    that's another big NO! - they are plugs for the cooling system, antifreeze mix runs through the turbo exhaust shell to keep it reasonably cool @ 80 - 90 degs C

  4. #4
    Join Date
    Apr 2011
    Location
    Boat- SoF
    Posts
    4,862

    Default Re: External turbo temperature, how to fix a thermocouple on

    Another No as if internet bought the thermocouples will probably melt potentially taking out the turbo if upstream ..

  5. #5
    Join Date
    Apr 2011
    Location
    Boat- SoF
    Posts
    4,862

    Default Re: External turbo temperature, how to fix a thermocouple on

    If your boats stored ashore on a trailer , then prop hygiene should be exemplary? As should hull fouling .
    We know you have over propped it from other threads regarding not being able to reach rated rpm with the replacement duo prop set .
    It’s highly likely if not a dead cert you are gonna run easily and unknowingly run into elevated EGT territory as it stands .

    Another delta you could use is your fuel consumption.
    If that rockets at said new cruise speed with the prop set then there you have it .
    Surely that’s a none invasive and crucially reversible thing to do first before drilling holes in expensive cast iron double skinned parts .

    If it’s correctly propped and obviously always gonna be clean then you can use VP,s rule of thumb WOT minus 10 % or whatever the manual says ?
    So a 3800 rpm WOT mean cruse at 3400 or lower in VP speak .

  6. #6
    Join Date
    Mar 2002
    Posts
    17,099

    Default Re: External turbo temperature, how to fix a thermocouple on

    Quote Originally Posted by Portofino View Post
    Another No as if internet bought the thermocouples will probably melt potentially taking out the turbo if upstream.
    Yup, another big NO, but for very different reasons, L.
    No probes would ever melt, because all you can reach through that plug is the engine cooling liquid, not the turbo and the exhaust gas.
    I'm not positive about your engines, but in MAN V engines that plug is only meant to avoid air traps when refilling the closed cooling circuit, since the turbos are positioned right above all other engine parts.
    In other words, you could fit there a bulb for the cooling liquid temp, not an EGT probe.

  7. #7
    Join Date
    Mar 2004
    Posts
    5,924

    Default Re: External turbo temperature, how to fix a thermocouple on

    Ah that’s how the turbo works, liquid cooling, explains why it does not get red hot on the outside.

    Was musing about fitting the thermocouple external on the turbo.
    only ‘hole’ would be to mount the probe externally on the plug, but no point obviously.

    Asking all these dumb questions ......

    p.s.
    The exhaust elbow has never been cleaned or replaced, 20 years, 450 hours
    So that is going to be checked first
    Then the second 2 min WOT run, after the engine has warmed up
    If / when I don’t get sufficient revs it’s smaller props and run that at 3200 max

  8. #8
    Join Date
    Apr 2008
    Location
    Isle of Man
    Posts
    1,910

    Default Re: External turbo temperature, how to fix a thermocouple on

    Prop down to get rated wot (3800)

    By bbq wireless meat probe and tape to short rubber exhaust between elbow and exhaust tube on outdrive with amalgamation tape. This will give you and indication of loss of sea water, things getting hot.....get out and enjoy it

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