How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
Type Your Boat Question Here...
Dominick is online now
A new question is answered every 9 seconds

I have twin 2009 150 hp opti's the stbd one acted up shortly

Customer Question

I have twin 2009 150 hp opti's the stbd one acted up shortly after accelerating with a loud horn, check engine light, and rpm reduction of appox. 2250 rpm I have merc monitors on both engines. I repeatly restarted the engine with the same results I spoke to my merc mech. his suggestion was to change impeller,thermostats,poppit,and clean out screen and replace psi sender. I keep my boat on a lift only use this one for off shore bottom fishing so it only has 165 hours on it I replaced both thermostats went for a ride and every thing was fine, but this very problem happened last year twice the only difference is I did NOTHING then and the next 2times I used the boat it ran fine. The pee out put is fine as are head temp and when this happens my monitor shows appox. 150 degrees. Along with problem I have another concern erratic high psi on both engines when running the boat at high rpm for a few min.(25-45 psi) been told to clean grey tube
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you.

Was the horn that went off a steady tone or a beeping one?

When was the last time that you had the impellers replaced on both engines?

Was there any text on the monitor screen when the alarm went off?

Customer: replied 1 year ago.
horn steady check engine light on rpm could not exceed 2250rpm
Expert:  Charles replied 1 year ago.

The steady horn is for overheat. There are three temp senders on this engine. One in each head and one in the air compressor.

Did your tech scan the engine to see which sender went off?

Are you near the boat currently and ready to check some items?

Customer: replied 1 year ago.
No just what I just sent to you
Expert:  Charles replied 1 year ago.


Are you near the boat?

Customer: replied 1 year ago.
Customer: replied 1 year ago.
He is too busy and pretty far away, my boat is on a lift, that's why I'm asking you.
Expert:  Charles replied 1 year ago.

I cannot come out there. This site is question and answer only. I can talk you through how to check the items. Is that what you were looking for?

Customer: replied 1 year ago.
I was hoping you could narrow down some of the things I could look into rather than replace every thing in the cooling system as my mech?? want to do. Also what about the high psi readings on BOTH engines.
Expert:  Charles replied 1 year ago.

That could be a T-stat sticking. At what RPM is that pressure reading?

I take it these are used in Salt Water correct?

Customer: replied 1 year ago.
I replaced both thermostats and the engine ran fine, as I mentioned this happened last year and I did nothing and the problem went away Yes used in salt water and flushed after every use. the old thermostats that I replaced looked good and checked out fine and I don't think they were the problem. I don't feel confident running offshore with this intermitting problem
Customer: replied 1 year ago.
Are you still there
Customer: replied 1 year ago.
I assume our session is over. Cancel my subscription.
Expert:  Charles replied 1 year ago.

Yes I am still here. You replied when I was eating lunch.

When was the last time that the impellers were replaced?

At what RPM is the water pressure reading that high?

Related Boat Questions