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671 TI temperature reading

Discussion in 'Ocean Yacht' started by Boomer, May 10, 2018.

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  1. Boomer, May 10, 2018
    #1
    Boomer

    Boomer Senior Member

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    Not sure if my temp. gauge is correct. Where should I point a infrared gun to determine the correct motor temperature when running? Exhaust manifold, oil pan, exhaust pipe?
  2. mwwhit1, May 10, 2018
    #2
    mwwhit1

    mwwhit1 Senior Member

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    You want to point it where the temp sender is. That is on top of the motor next to the valve cover on the exhaust manifold side. This way you are reading the same place the sender is. Probably will be a few degrees cooler since you are on the outside of the painted manifold.
  3. Boomer, May 10, 2018
    #3
    Boomer

    Boomer Senior Member

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    Thank you sir!!!
  4. Pascal, May 10, 2018
    #4
    Pascal

    Pascal Senior Member

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    Your temo gauge measures coolant temp so takiing a reading on oil pan or exhaust is irrelevant.

    As mentioned above, measure at the temp sender although the thermostat housing is a pretty good spot too. Move the IR around to find the hottest spot there
  5. Boomer, May 10, 2018
    #5
    Boomer

    Boomer Senior Member

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    Thank you sir!
  6. Capt Ralph, May 10, 2018
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    What are your gauges reading and at what rpm.
    Are you noticing new temp changes or have always been a concern?
    I like to read before and after the thermostats and the middle of the expansion tank under load when questioning engine and cooling systems.
    More data on the engine assembler (Detroit, JT, Convington, other) And HP tune (TI - TIB), would be of help.
  7. Boomer, May 11, 2018
    #7
    Boomer

    Boomer Senior Member

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    J&T...671 TI...1983 models...port motor reads low-160- and stbd shows 200 at 1950 rpm....just bought the boat last month so trying to figure everything out before any damage is done...at 1000 rp.s, port motor same and stbd motor goes down to 180...just had both motors descaled, new impellers,, and fwc system back flushed
  8. Capt Ralph, May 11, 2018
    #8
    Capt Ralph

    Capt Ralph Senior Member

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    These are gauge or i/r readings?
  9. Capt Ralph, May 11, 2018
    #9
    Capt Ralph

    Capt Ralph Senior Member

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    Did you descale the thru hulls? Replace the hoses from the thru hulls to the raw water pump?
  10. Boomer, May 11, 2018
    #10
    Boomer

    Boomer Senior Member

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    Gauge....i wanted to ir the motors to verify true readings
  11. Boomer, May 11, 2018
    #11
    Boomer

    Boomer Senior Member

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    Negative...but great sugguestion...will pull them to verify no growth
  12. Capt Fred, May 11, 2018
    #12
    Capt Fred

    Capt Fred Senior Member

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    If the IR gun confirms the 160 reading on the port at 1950, then there is a problem there. Probably the thermostat is not closing.
  13. Capt Ralph, May 11, 2018
    #13
    Capt Ralph

    Capt Ralph Senior Member

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    I remember an old (OLD) Hatteras that would get hot at higher rpms.
    The inside of the hose de-lamated and would draw in and restrict the low side to the raw water pump.

    Inside external strainers and cocks cause issues also.

    But hitting the same spot between engines with an I/R gun is a good tool.
  14. Lepke, May 12, 2018
    #14
    Lepke

    Lepke Member

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    The temp gun is also good for pointing at the exhaust ports of the head. It won't show exhaust temperature but will show if the cylinders are pulling equally.
  15. RT46, May 13, 2018
    #15
    RT46

    RT46 Senior Member

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    i use the IR gun to take tamp readings at different spots on the engine.
    I then shoot the same spot on the other engine and compare numbers.
    Any significant difference is usually a reason to further investigate.
  16. Boomer, May 20, 2018
    #16
    Boomer

    Boomer Senior Member

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    Thanks for the suggestions...she is definitely pumping the same amount of water out both exhausts
  17. Capt Ralph, May 20, 2018
    #17
    Capt Ralph

    Capt Ralph Senior Member

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    It's hard to see the same amount of water at speed.
  18. Boomer, May 28, 2018
    #18
    Boomer

    Boomer Senior Member

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    Well...pulled the thru hull hose to the motor...looked good....good water flow thru seacock...put ir on the cylinders and had a low of 140 and a high of 180...all others around 160...btw, was at the slip with motor revved. ..guess gauge is off? Temp comes back down when at idle...any issue to worry about?
  19. Capt Ralph, May 29, 2018
    #19
    Capt Ralph

    Capt Ralph Senior Member

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    You can swap senders between the motors as a test.
    Or run temp wires and criss-cross the senders for that same test. Make sue the engine blocks are B- strapped together (as normal and required) before the criss-cross test.