Mercury, 150 four stroke, 2015

by Jacob
(Ocean City, MD)

I bought this boat with only 5 hrs on it and it has a Merc 150 4 stroke motor. The first few times I took it out, the boat ran great. Top speed of 36 MPH at 5400 RPM for a 25' Tahoe Tritoon Entertainer. I didn't run it for the next 2-3 weeks, left it in the water(with the motor up) and then my next trip out I couldn't get it above 24 MPH and 5400 RPM. I went to the dealer and they claimed I had growth on the bottom of the boat and that was the cause. They were wrong, I paid to have the boat cleaned and that still didn't get the MPH back up to the original speed. So I dealt with this issue for the rest of season. The next season I had the bottom painted thinking this may resolve any drag issues.....no change in speed. Next I went through the motor and changed both fuel filters, impeller, spark plugs, engine oil and lower unit gear oil, and then I checked the pontoons to make sure they did not have water in them and still no resolve. So I am at the point to either replace the motor with another manufacturer or sell the boat all together. I have contacted mercury multiple times with no help and no one im my area really works on Mercury which is a whole other issue.....LOL...lesson learned. I have just been informed by my auto mechanic who use to work on boats mention something about a gasket or seal either behind the prop or somewhere in the lower unit that may be the problem.......Any ideas from this group would be greatly appreciated. I really enjoy my boat and just want this problem to go away.