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    baffled-gctid357636

    i have a 2008 bayliner 195br flight series w/ 5.0 merc, carburated. last year my temp started running hotter than normal sometimes will reach approx 185 and the alarm sounds. i naturally replaced the impeller in outdrive(old one was in perfect shape)& replace t-stat. no change. i borrowed 2 different infared temp detectors and discovered engine is not running hot at all, hottest point was at t-stat housing and averaged betweed 163-168f, no hotter than 168. i replace temp sender for guage, still runs hot. i thought maybe guage is malfunctioning, however i discovered the audible alarm is not tied in with guage, it is getting reading from another sensor.so 2 independant systems are saying eng is overheating! i thought maybe a ground probem but i cannot find any poor grounds or broken wires. any suggestions on this one? help?

    #2
    Elbows maybe clogged. Any heat exchanger maybe clogged.

    Pull the Hose off that comes in from the transom at the first point it enters the motor, it maybe the t-stat housing or a heat exchanger.

    With the drive submerged start the motor you should have about a 8-12" fountain with the hose held straight up. Quick shut off the motor, you need about 3 seconds to see if you got good water coming into the motor.

    Now say you have good water coming into the motor the clog is downstream.

    If you do not have good water coming into the motor then you have a clog in the drive or the nipple that passes thru the transom from the drive.

    In my opinion the age of your boat if you boat in saltwater you on the cusp or passed the cusp of replacing the elbows.
    Be good, be happy, for tomorrow is promised to no man !

    1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

    '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

    Manalapan N.J

    Comment


      #3
      Chief,

      wouldn't those things show with an ir temp detector??????????

      Comment


        #4
        never boated in salt water. according to the ir detector the engine is not running hot

        Comment


          #5
          they would. ir detector showing 163-168 at t-stat housing - incidently, temp sender in t-stat housing.

          Comment


            #6
            2 independent sensors have more credibility than IR gun to me.

            those probes are right in the water. the IR just shows surface temp. which you can feel with your hand more accurately.

            some IR guns read way off with shiny painted surfaces.

            if you can't keep your hand on the risers whilst underway, you are overheating.

            uncomfortable to touch ok, burning you immediately not ok.

            there's my high tech IR tool...

            overheating at idle = impeller

            overheating at high rpm = impeller housing sucking exhaust

            either is cured with a new impeller kit.

            Comment


              #7
              Dont know if it applies but I replaced my impellers this summer due to high temps. The boat ran cooler for one trip and then back to the high temps. I looked at the impellers again and noticed when I installed them the little rubber gasket was not seated properly allowing air in. I reseated the gasket using a dab of silicone an all was well for the rest of the summer

              Comment


                #8
                If he is not getting good water to the engine then for sure it can be a bad impeller, or a blockage in the drive or the trasom pass thru nipple.

                The key here is to find if he has good water to the engine.

                When installing the impeller, some people do not look at the surface of the pump housing where the impeller makes contact. If there are groves then the impeller cant push the water.

                Long winded post this one.

                Check if you have good water to the engine first...... post back we can go from there.

                The drive must be submerged... not hooked up to a garden hose !!!!!

                A side note: I surly wish that people put up a general area in the real world where they are located. I lost count how many people i went down to local guys boats and within a half hour determined what caused the problem they had.

                I work for free it's a hobby.. the point is there are many members here who do the same.
                Be good, be happy, for tomorrow is promised to no man !

                1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                Manalapan N.J

                Comment


                  #9
                  The P of E (process of elimination) will never let you down. One item and ONLY one item at a time.

                  You mention pump in out drive, so this would be an A drive.

                  Find a schematic of your exact cooling system.

                  Follow the path from the inlet in the lower unit, to the sea water pump, from the pump up to the upper unit, from the upper unit into and through the Gimbal Bell and Gimbal housing, from there to any P/S oil cooler (if equipped), from there to the T-stat housing where the engine circulating pump is supplied.

                  This is the same area where whatever cooling water is NOT used by the actual engine demands, passes right on by and into and out the exhaust manifolds/risers.

                  You may need to pull your risers and examine the sea water transfer ports. If these are rusted and are restricting sea water flow, it may be part or all of your problem.

                  Don't stop here.... continue following the path until you exit the drive/prop.

                  Learn the path, and follow the flow. You'll find it!

                  Hopefully others will chime in and guide you to a schematic.

                  Meanwhile, plug in your engine serial number here and see if this can bring up a system schematic.
                  Rick E. Gresham, Oregon
                  2850 Bounty Sedan Flybridge model
                  Twin 280 HP 5.7's w/ Closed Cooling
                  Volvo Penta DuoProp Drives
                  Kohler 4 CZ Gen Set

                  Comment


                    #10
                    Be aware, I have an aftermarket heat exchanger. when I run w.o.t. for more than a few minutes my engine begins to heat up and will continue to rise till i reduce speed. Never noticed this issue for years as i dont run that fast. Discovered this after replaceing manifolds and then testing the install. had a few techs tell me this is an issue with the alpha pump being marginal. It is worse in Florida than Ontario due to warmer water. I can run up to 28 mph no problem. But now that I know it bothers me. Im told I can install a second pump.

                    Comment


                      #11
                      I appreciate your input. I live in boise ID. my boat has fairly low hours and water always drained from engine when not in use. My prev boat was 10 yrs old and never had any rust issues, i cant imagine rust creating blockage on a 4 year old boat...any possible though. I did inspect and found no grooves at all on impeller housing. Heres the thing though, the guage still runs hot on trailer with muffs on and water blasting, the exhaust risers feel relativly cool. im still not a 100% my eng is overheating - another clue is my oil pressure guage has been running higher than normal to, close to 70- 80psi on start up then will drop back back to 40-60 as warms up (at idle). I realize these guages are not exact but more of a general indicator. oil guage high, temp guage high, coincidence?

                      Comment


                        #12
                        pjumper wrote:
                        I have an aftermarket heat exchanger. when I run w.o.t. for more than a few minutes my engine begins to heat up and will continue to rise till i reduce speed. Never noticed this issue for years as i dont run that fast. Discovered this after replaceing manifolds and then testing the install. had a few techs tell me this is an issue with the alpha pump being marginal.

                        Im told I can install a second pump.
                        Yes, I've done this for an A drive system.

                        You have to maintain the A pump as the upper unit relies on this for cooling.

                        I believe that some may use a drive shower in lieu of the A pump.

                        It's easy to just port it overboard, or connect it in with the new seacock.

                        flyinghigh wrote:
                        I appreciate your input. I live in boise ID. my boat has fairly low hours and water always drained from engine when not in use. My prev boat was 10 yrs old and never had any rust issues, i cant imagine rust creating blockage on a 4 year old boat...any possible though.

                        im still not a 100% my eng is overheating - another clue is my oil pressure guage has been running higher than normal to, close to 70- 80psi on start up then will drop back back to 40-60 as warms up (at idle). I realize these guages are not exact but more of a general indicator. oil guage high, temp guage high, coincidence?
                        The cost to check the transfer ports is the cost of Man-to-Riser gaskets.

                        I'd do this and you will have either found a problem, or will have eliminated this.

                        Have you checked by serial number to see if Merc issued any service bulletins on similar issues... perhaps higher than normal voltage readings that may affect instuments..., for example.

                        .
                        Rick E. Gresham, Oregon
                        2850 Bounty Sedan Flybridge model
                        Twin 280 HP 5.7's w/ Closed Cooling
                        Volvo Penta DuoProp Drives
                        Kohler 4 CZ Gen Set

                        Comment


                          #13
                          flyinghigh wrote:
                          however i discovered the audible alarm is not tied in with gauge, it is getting reading from another sensor.so 2 independant systems are saying eng is overheating! i thought maybe a ground probem but i cannot find any poor grounds or broken wires. any suggestions on this one? help?
                          So... the gauge is a variable thermistor (meaning it provides a variable resistance to a gauge) while the alarm is connected to a thermal switch (closes after temp is reached). If the temp is normal at the alarm switch (via infrared) I'd pull that and test it in a pot of water on the stove and see when it closes and re-opens in a controlled environment. They're not that expensive, so it might even be easier to change the sending unit.

                          You're 100% they have not been switched? They are often directly across from each other on the block.
                          Custom CNC Design And Dash Panels

                          iBoatNW

                          1980 CHB Europa 42 Trawler- "Honey Badger"

                          Comment


                            #14
                            before you get too carried away,get a manual gauge or set of gauges at local auto parts place. They are cheap like $20. substitute sender and gauge in a temporary fashion and try boat. IR gun shouldnt lie that bad IMO. The "hand holding" advice is also very good IMO.

                            Comment


                              #15
                              Mike brought up a good re; the over-temp "switch".

                              This is not a sender, but is rather a switch...... so it would be doubtful that varying voltage would have an affect on one.

                              Gauges and senders, on the other hand, may be affected by voltage variances.

                              Perhaps test/varify your IR gun with a know temperature source(s).
                              Rick E. Gresham, Oregon
                              2850 Bounty Sedan Flybridge model
                              Twin 280 HP 5.7's w/ Closed Cooling
                              Volvo Penta DuoProp Drives
                              Kohler 4 CZ Gen Set

                              Comment

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