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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10896
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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Have 2015 Tahoe 215 starts and runs fine low throttle then

Customer Question

have 2015 Tahoe 215 starts and runs fine low throttle then justa after plaining out alarm starts sounding and engine power oscilates and cuts back power
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

When was the last time you had the water pump serviced? How many hours are on the present water pump?

Could I get the make model and serial number of the engine please?

Customer: replied 1 year ago.
2014 model 5.0 mercruiser I/o on a Tahoe 215 was taken to dealer at 20 hrs to check out problems maybe another 10 hours use this summer after it was winterized......I used in saltwater about 4hrs 2 weeks ago ran fine no problems then flushed at home attaching cuff on hose....maybe for 5 min....then shut off.....ran this week in freshwater and seemed really sluggish and just not the same power the alarm thing started,,,
Expert:  Tan replied 1 year ago.

Is the alarm continuous? What does the temperature gauge read when alarm sounds? What kind of oil pressure are you showing on the gauge when alarm sounds?

Is this the original water pump?

Customer: replied 1 year ago.
original waterpump.....temp actually reading a little lower than normal...140...and oil pressure is around 70 I think....just off the top mark on the gauge....all gauges read where they usually are except temp being a little lower than normal
Expert:  Tan replied 1 year ago.

What is the alarm doing is it constant or a intermittent beep.

Customer: replied 1 year ago.
if I just idle along everything sounds fine and runs only happens when I begin to accelerate and is intermittent alarm...I got it to plane out a few times runs and sounds fine for about 5 min...then alarm ans starts oscilating engine power
Expert:  Tan replied 1 year ago.

Ok the only way to find the issue on this engine is to have the engine scanned. The only reason the engine goes into guardian mode is for low water pressure, over heat or low oil pressure. So one of these sensors are failing or you have an actual issue. The water pressure sensor is the most likely cause of the alarm since the oil pressure and water temp are good.

Now is this the original water pump?

Customer: replied 1 year ago.
original water pump
Expert:  Tan replied 1 year ago.

Ok your symptoms are of a cooling system issue. What has happened is the water pump is weak and doesn't produce the water pressure it should. It's just enough to keep the engine over heat alarm form going off. Then when you power up the engine has no water pressure due to a weak pump causing the alarm to sound and put the engine in guardian mode.

The water pump service intervals are once every season or 100 hours of use or which ever comes first.

The water pump impeller becomes stiff from age and lack of use not producing the water pressure it should.

So I would have the water pump serviced as that is really the only thing that will cause all the symptoms you are having.

The water temp is another issue all together most likely stuck thermostat.

Does this make sense?

Post back with questions.

Customer: replied 1 year ago.
Expert:  Tan replied 1 year ago.

Your welcome...........Thank you......Tan

Have the thermostat checked also as this can cause the temp to read low. This will also have an affect on water pressure. The alarm is being sounded by the water pressure not engine temp.

Post back if you need further assistance.

Please don't forget to positively rate me as this is the only way I get paid for helping you......Thank you........Tan

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