9.5 Johnson Temperature

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  • RANDY SCHNEIDER

    US Member - 2 Years
    Replies: 10
    Topics: 4
    #262520

    Hi all, It’s been a while since I’ve worked on one of these.   I have gotten it pretty much cleaned up with good compression and pumping water well.  The water exiting with the exhaust  relief is pretty hot, and the heads are quite warm.  I have been used to no cooling control so just want to make sure I don’t roast this one.  I pulled the thermostat out and heated it up on the stove, in water.  Not sure I would tell what moved.   If I press down on the base of it I can push it up against the spring, but I don’t see any disk open like in a car thermostat.  I must be getting old.   I put hand full of water on the head and cylinders, and they don’t steam when I am running it.  I am guessing its running about 150 or better as it is pretty uncomfortable to the touch.  For some reason I had thought the whole disk at the top of the thermostat would open up when I got it pretty hot on the stove.  This one looks to be a 66 motor.


    frankr

    US Member - 1 Year
    Replies: 6245
    Topics: 49
    #262528

    The little disk will rise when temp is reached.  You probably didn’t get it hot enough.  When they fail, they almost always fail in the open position.  Almost.


    RANDY SCHNEIDER

    US Member - 2 Years
    Replies: 10
    Topics: 4
    #262589

    Thanks Frank, I will watch it,  back into the soup pot with it.   I am used them reacting pretty fast, but like i said, its been a while since I have  work on these pumpkin heads.  Its tossing a lot of water out with the exhaust bypass, does that slow down some when it starts running to internal cooling?  I was just running in high neutral so not pressing it too hard yet.


    frankr

    US Member - 1 Year
    Replies: 6245
    Topics: 49
    #262590

    It doesn’t actually “switch to internal cooling”.  There are two water flow paths through the powerhead.  One path is always open to free flow and is not thermostat controlled.  The other path is thermostat controlled and flows according to thermostat state, which is constantly sampling and opens/closes as necessary.  Danged if I can tell the ‘stat position by observing the discharge.


    crosbyman

    Canada Member - 2 Years
    Replies: 2802
    Topics: 275
    #262591

    see pict.

    Joining AOMCI has priviledges 🙂


    Mumbles

    Canada Member - 2 Years
    Replies: 5514
    Topics: 293
    #262680

    Normally, the 9.5’s don’t spray a lot of water out the back until the motor warms up and the T-stat opens up. Then it gushes out. This is the same for the early 9.9/15 horse motors. If the motor is idling in a barrel, it might not be  be generating enough heat to open the stat so making some horsepower by putting it in gear and revving it up a bit should heat it up enough to open the stat.

    At lower speeds, you will see the water outflow fluctuate as the stat opens and closes. At higher speeds, the flow should be steady.

    One symptom of a stat which is stuck open is poor extended idling and wet or fouled plugs as the motor can’t get hot enough to burn off the oil.

    Thermostat-Schematic

    Some bad stats.

    9.5-T-Stat
    Stuck-T-stat
    QD-Tstat
    9.9-15-Tstat-Gaskets-002

    And this beauty, which I found being sold on Ebay  for a premium price.

    • This reply was modified 1 month ago by Mumbles.

    Mumbles

    Canada Member - 2 Years
    Replies: 5514
    Topics: 293
    #262691

    Well that didn’t work so here’s the gem I found listed on Ebay.  Buyer beware.

    T-Stat-Ebay-1

     

     


    billw

    US Member - 2 Years
    Replies: 1809
    Topics: 54
    #262711

    I never knew there was rubber in them! Thanks for that great diagram! Very funny about the one on eBay. Although a little troubling….

    Long live American manufacturing!


    RANDY SCHNEIDER

    US Member - 2 Years
    Replies: 10
    Topics: 4
    #263516

    Thanks much the pics are a great help.   When I start I have a lot of water out the exhaust tube on top.  I thought they ran at  a little uncomfortable temp when working.  I should get out the IR and see where it is at.  I usually get yelled at cause it is in the kitchen for chocolate.

    Randy


    fleetwin

    US Member - 2 Years
    Replies: 4290
    Topics: 42
    #263524

    Like Frank says, thermostat operation would be near impossible to judge from the cooling water outlet on this engine. I would be more suspect of a worn impeller/housing if the outlet water volume seems to drop after start up. Grooved/pitted impeller housings are often overlooked as a source of poor water pump performance.
    Have you had the gearcase off lately? I only ask because these engines are low in the water and more prone to spline seizure, especially in salt water. So, be very careful if you are removing the gearcase for the first time. Forcing the gearcase down/off, while leaving the driveshaft stuck in the crank splines creates quite a mess.


    RANDY SCHNEIDER

    US Member - 2 Years
    Replies: 10
    Topics: 4
    #263821

    Hi,

    Water pump is good, no marks or cracks.  I had figured on changing it, but when I pulled it apart it looked real good.  All fresh water motors here.  I did put new seals in the lower unit.  I think it will be OK.  The proof will be in a longer run.   My thermostat doesn’t look to be extended up like the one you showed.   Thanks.

    Randy

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