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    #16
    Hi Guys,

    I should have mentioned also the Oil pressure is 45 - 48 psi.

    Comment


      #17
      Hi guys,

      Plenty of fresh oil as well. Also as a reminder when the Temp gauge stopped working is exactly when the Alarm started going Off...

      Comment


        #18
        My point is that the oil presure sender and the oil pressure switch are totally independent. A bad switch can trigger the alarm, even when the pressure is good. It's happened to me on 2 separate occasions. In both cases is was a bad switch.
        1999 3788, Cummins 270 "Freedom"
        2013 Boston Whaler 130 SS
        Anacortes, WA

        Comment


          #19
          Eddie has erratic temp gauge readings along with an alarm at high rpm (up on plane) so we’re assuming it’s temp related but I do agree that any of the alarm switches (temp, oil, drive lube) can be faulty triggering the alarm. I would still like to know what his temp readings are with the IR gun up on plane at 3500 rpm
          Dave
          Edmonds, WA
          "THE FIX"
          '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
          (.030 over-Vortec top end-part closed cooled)
          The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
          Misc. projects thread
          https://www.baylinerownersclub.org/f...56-gctid789773

          Comment


            #20
            Hi Guys,


            Keep in mind the one thing I find "VERY ODD" is the Temp Gauge started acting up when the Alarm started going Off. The below steps are what I ended up doing when the Alarm went off. By the time I got back to the dock approx. 45 mins the Temp Gauge was dead. I find that Alarm going off and the Gauge acting up at the same time a very strange coincidence. Especially when I Tested the Temp Gauge and it Tested OK.



            1. THE ALARM GOES OFF WHEN UP ON PLANE APPROX. 3400 TO 3600 RPM.


            2. I DROP DOWN TO 1000 TO 1200 RPM AND THEN WITHIN 2 MINUTES THE ALARM STOPS.


            3. IF I GET BACK ON PLANE APPROX. 3400 TO 3600 RPM AGAIN WITH IN A FEW MINUTES THE ALARM GOES OFF AGAIN.


            4. AGAIN... I DROP DOWN TO 1000 TO 1200 RPM AND THEN WITHIN 2 MINUTES THE ALARM STOPS. IF I STAY AT THIS RPM RANGE OR A BIT HIGHER THE ALARM DOES NOT COME BACK ON. EVEN IF I CRUISE FOR 20 MINS.


            5. THEN I TRIED RAISING THE THROTTLE SLOWLY TRIM DOWN, TABS DOWN, APPROX. 2000 RPM ON PLANE ( TAKES 3-4 MINS ) BUT I GETS ON PLANE THEN WITHIN A FEW MINS THE ALARM GOES OFF.



            Note:
            ANYTIME DURING THESE RUNS ABOVE THE OIL PRESSURE HAS NOT CHANGED FROM 45-48PSI FROM IDLE TO FULL THROTTLE AND ANYWHERE IN BETWEEN.



            Thanks Again

            Eddie


            Comment


              #21
              From your description it sounds like your over heating up on plane (higher rpm range) and the temp switch is doing its job. It’s very possible you have a separate issue (faulty sender or.....) going on with the gauge. Still want to know what the IR gun tells you while on plane.
              Dave
              Edmonds, WA
              "THE FIX"
              '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
              (.030 over-Vortec top end-part closed cooled)
              The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
              Misc. projects thread
              https://www.baylinerownersclub.org/f...56-gctid789773

              Comment


                #22
                I am checking the Temp on Plane today.

                Ed

                Comment


                #23
                Hi Guys,

                Went out for Test ride and took Temp readings:

                I need to preface the readings with an update:

                I installed a new Sierra Temp Sender (wanted the Mercury product they did not carry Mercury products) anyway right of the start the Temp sender in the engine was a 3/4" nut and the Sierra Temp Sender was 7/8". I then started her up and started down the canal. Half way down I noticed that the Temp Gauge was at 175deg. So surprised at the temp because it has never been this high, I started to watch it. Within seconds it starts to drop 150 then 125 then back up over a period of 10 seconds to 175 deg. Then it would drop to 150 then back up to 175deg. Then it would repeat dropping to 125 deg and slowly back up to 175 deg.

                THE READINGS:

                After 25 minutes of running at 1200 to 1800 RPM - THURSDAY NIGHT

                Starboard Riser - 106
                Port Riser - 96
                Manifold - 116
                Thermostat Cover - 122
                The cover where the four hoses connect.- 109
                The Temp Sender unit.- 126




                TODAY - SATURDAY

                Starboard Riser - 153
                Port Riser - 128
                Manifold - 119
                Thermostat Cover - 124
                The cover where the four hoses connect.- 115
                The Temp Sender unit.- 128


                The Temps were not that much different and all within tolerances.

                Not sure if the Erratic Temp Gauge is OK or not. I tested it the other night by taking the sender wire to ground and turning ON the Ignition and the gauge went all the way up to 250 and dropped down to it's resting spot below 100 when the ignition was turned OFF.

                I am also wondering if the New Sender is the correct one. Especially after using ( some of you will know) Using a Sierra Gimbal Bearing caused my Banging issue in the lower unit. Replaced with Mercruiser product and that fixed the issue. I hope they know the products at the local marine store since this is the second part I bought that I am skeptical about whether if its the right one. thicker then the Mercruiser one.Since the Sierra Gimbal Bearing was the wrong one. The inner size was 1/4"

                Thanks Again
                Ed


                Comment


                • Nauti_Mike
                  Nauti_Mike commented
                  Editing a comment
                  Starboard rise is too hot. What manifold is the reading of? I take or exhaust? If exhaust are they both reading this temp?

                #24
                Guys,

                I need a bit of help locating these Senders and Switches.

                I replaced the Temp Sender. That caused another situation with an Erratic Temp Gauge which was previously tested OK as I wrote about on the above post.

                The Sender was easy right on the Stat Housing, but on the opposite side of the housing is where I thought the Temp Switch was but there is a Brass plug there instead. Where is the Temp Switch?

                Does anyone actually know what the Part Number is the a Sierra Temp Sender? I want to confirm I have the right one.


                **** I want to check the Oil Pressure switch and the Oil pressure Sender. Where are the oil Pressure Sender & the Oil Pressure Switch?

                I know I can trace the wire, but since I have a Black or Dark Brown wire with a TAN stripe on the Temp Sender, I am not sure if some of the other wires may be slightly different from the standard color code.

                2000yr.
                7.4 MPI Bravo III


                Thanks Again

                Ed



                Comment


                  #25
                  Both the temp sender and temp alarm switch should be in the thermostat housing, post a picture to confirm. Oil pressure sender should be on rear of engine next to the distributor. The oil pressure switch should be on port side of the block next to oil filter .
                  1997 Maxum 2400 SCR 5.7LX Bravo II

                  Mike

                  Comment


                    #26
                    OP mentioned engine is an MPI. Good chance it's some other sensor causing the alarm (water flow, manifold presure etc...). This is where you need to connect a computer to diagnose what's going on.

                    Comment


                    • Nauti_Mike
                      Nauti_Mike commented
                      Editing a comment
                      Yup a fault code should be stored in the computer since this is reoccurring all the time.

                    #27
                    Not sure about big blocks. That's a picture of the raw water thermostat housing from my 2003 6.2l mpi motor.
                    temp sender on the left
                    Temp switch on the right Click image for larger version

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                    1992 2452
                    5.0 alpha1 gen2

                    Comment


                      #28
                      Hi Guys,

                      1. THE WATER TEMP SWITCH: I think I found the Temp Switch hiding under the T-Stat cover. Two wires (Brown & Yellow) coming off of the switch. Pics #1, 2, 3..

                      2. THE WATER TEMP SENDER: Pic #4 - Tan w/ Brown Stripe (At least that is what it looks like).


                      3.THE OIL SWITCH: Pic #5 - Lt. Blue wire

                      4.THE OIL SENDER: Pic #6 - I think it was Dark Blue Specs say Purple????


                      5. THE LOWER UNIT - LUBE OIL SWITCH ( A Pressure Switch): Pic #7 - Tan & Black or Brown.


                      ================================================== ================================

                      The Water Temp Switch had two wires (Brown & Yellow) I was not expecting 2 wires, so that I was not able to Test Continuity.

                      The Oil Switch was very rusty, I tried to clean it up & test Continuity. I could not get a result from the TEST.

                      The Oil Lube Tank - I removed the tank from the hold down strap & disconnected the two wires. Then I checked for an Open or Closed circuit via continuity and circuit tester on the Ohm Meter. I filled it back up to the top with oil and proceeded to do the same continuity Test again. In neither Test - Lube tank Empty or Filled did I get any Continuity. The wires were 1- Black or Brown & the Other was Tan connected to the 2 Black wires coming from under the lube tanks switch.

                      So out in the Bay:

                      I decided to disconnect:

                      The Water Temp Switch - The Alarm under the dash went OFF in 30-45 seconds after being on plane.

                      Then I disconnected the Oil Switch: - The Alarm under the dash went OFF in 30-45 seconds after being on plane.

                      Then I disconnected the Lube Oil Tank Switch - The Alarm under the dash went OFF in 30-45 seconds after being on plane.


                      Now All 3 wires are disconnected from the Engine and I started her up and (Can you Guess) - The Alarm under the dash went OFF in 30-45 seconds after being on plane. Now it's my understanding there are NO Connections to the Alarm via any or all 3 switches so the Alarm should not be going OFF.

                      Additionally I Tested the lube Switch:
                      I also jumped the 2 wires from the Lube switch at the Harness side - 1- Black or Brown & the Other was Tan connected to the 2 Black wires coming from under the lube tanks switch. I jumped the Black or Brown & the Other was Tan together on the harness side and Tested again.

                      Each time I Tested the Engine was shut down and the wire was disconnected & then the Engine was re-started and the boat taken up on plane. Again after 30-45 seconds the Alarm goes OFF.

                      Also Note: There is a Beeper Alarm under the dash & a Buzzer type Alarm on the Engine somewhere.


                      I am at a loss here guys.


                      ================================================== =================

                      Also throwing this out there: I replaced the Water Temp Sender and the Gauge floats up and down smoothly from 125-deg. to 175-deg. and it just goes up and down. I did take the sender wire and grounded it & then Turned the Key to the ON position and the Gauge goes smoothly to 250 and back down to 100 when Ignition is turned OFF. I will post a video of it soon. Aslo the IR Temp gun still conforms to the same Temp readings as stated above in a prior post.

                      Thanks again guys for all of the responses.....

                      Thanks
                      Ed


                      ===============================================

                      Check out the Pics - They are labeled as well.

                      Comment


                        #29
                        Your t stat housing needs some serious TLC🤢
                        Typically Mercruiser alarm switches incorporated a tan wire for triggering the alarm. The switches are normally open during engine operation. If temp rises to the set threshold of the switch or oil pressure decreases to the set threshold of the switch or the drive lube gets low (simple float switch) that will close the switch (negative side of the circuit) and sound the alarm.
                        Dave
                        Edmonds, WA
                        "THE FIX"
                        '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                        (.030 over-Vortec top end-part closed cooled)
                        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                        Misc. projects thread
                        https://www.baylinerownersclub.org/f...56-gctid789773

                        Comment


                          #30
                          The sensor with two wires is the engine temp sensor used buy the computer.
                          1997 Maxum 2400 SCR 5.7LX Bravo II

                          Mike

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