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Thread: 8-71 TI Temp

  1. #1

    8-71 TI Temp

    Freshwater since birth 8-71 TI's in my boat. They have ran up to 180 when pushed up past 17-1800 rpm since I got the boat. Like most they build little heat at idle. Now my stbd. side tries to get up around 190 if I push them. Port is still hanging tough at 180. So I changed the impeller on the stbd. side with no change. I have never cleaned the heat exchanger. Nor do I know many that have in freshwater. So... how bad is pulling the HE and cleaning it and how bad is pulling the thermostats. I currently find myself lacking in the mechanic category unless I wait for Diesel Don to make his rounds. The manual states that I will need a seal puller for the thermostats that alone makes it sound tougher than any thermostat replacement I have done. Does anyone have a Part# for 170 thermostats for the 8-71s? Thanks

  2. #2

    Re: 8-71 TI Temp

    Go on to u tube and watch some videos on Barnacle Buster. When you replaced the impeller where all the fins attached? Hit both motors with a heat gauge while running. The gauge it self might be going bad.
    SEVEN
    1979 53' MY Hull #563
    Antioch, California

  3. #3

    Re: 8-71 TI Temp

    The old impeller looked good. I had it open so I replaced it anyway. I'm getting the temp reading on both stations. So it could be a sender I guess. Big problem is I have to be underway to get to the heating issue so it's hard to be at the helm and the ER all at the same time.

  4. #4

    Re: 8-71 TI Temp

    Maybe I can bribe somebody to sit beside that 8-71 with an IR gun...

  5. #5

    Re: 8-71 TI Temp

    If your anywhere near me I'll take a run with you.

  6. #6

    Re: 8-71 TI Temp

    My 8-71’s were doing the same thing and I just did the flush of the HE with vinegar, circulated for about 6-7 hours, ran today and temp stayed below 180 at all RPMs very happy with the results and pretty easy to do once I got all the parts together. John
    Mahalo V
    1974 53 Motoryacht
    Hull Number 406
    San Diego, Ca. Ready 32 Nordic Tug, Brunswick Ga.

  7. #7

    Re: 8-71 TI Temp

    You can switch the sending units from port to starboard to see if it’s the gauge
    SEVEN
    1979 53' MY Hull #563
    Antioch, California

  8. #8

    Re: 8-71 TI Temp

    Quote Originally Posted by SEVEN View Post
    You can switch the sending units from port to starboard to see if it’s the gauge
    or switch the gauges if you dont want to mess with the coolant going everywhere

  9. #9

    Re: 8-71 TI Temp

    Quote Originally Posted by Briankinley2004 View Post
    or switch the gauges if you dont want to mess with the coolant going everywhere
    Good point.
    SEVEN
    1979 53' MY Hull #563
    Antioch, California

  10. #10

    Re: 8-71 TI Temp

    You can do it. Get a slide hammer seal puller and change the seals and thermostats. I'll bet you have one that is not fully opening. With a freshwater engine, I'll bet its not the heat exchanger.

    https://dieselpro.com/detroit-diesel...al-186780.html

    https://dieselpro.com/thermostat-for...0-degrees.html

    https://www.harborfreight.com/heavy-...-pc-63268.html
    Sky Cheney
    1985 53EDMY, Hull #CN759, "Rebecca"
    ELYC on White Lake--Montague, MI

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