300 opti thermostat question

[nmliberator]

While on the water hose one thermostat reads 88 and the other reads 114. According to my temp gun. Last season my boat would hardly get up to 120 degrees. That's the reason for my inquiry. It's a 2007.

[PropWash]

You might have some small stones trapped in the thermostat, holding it open. When this happens the thermostat can end up passing too much water and never get hot enough to open more and release the stones.

Have you taken them out to see if they are clear? This is very easy - just have new gaskets available.

[nmliberator]

No hopefully will be warm enough to take them off today. I don't have any gaskets am I gonna need them for sure. If so I will wait until the gaskets get here.

[Euroski]

The only time my 2007 300xs would go above 120* is late summer when the water got into the 80*s. It's been like that since new. As for yours running different from side to side I don't know..

[nmliberator]

Found some little pieces if wood in the thermostat. Now it runs right at 100 and the other side is about 108. A little better anyway.

[PropWash]

As a point of reference my 300xs is a 2010. It warms up to 135-140 before thermostats open and then drops to 120 where it normally runs.

If you have found trash in the thermostats it might pay to run the engine (on the hose) for as short while without the thermostats in to try and flush through anything else still in there. The thermostats seem to trap debris pretty easily so I put my gaskets on with grease rather than any sealer. Using grease allows me to get the thermos out without destroying the gaskets if I need to. Mercury probably doesn't recommend using grease so up to you to make a call on that - has worked for me on this and other engines for years.

[nmliberator]

Do u think it would be worth my time to take the poppet out since there was trash in my thermostats.

[PropWash]

Definitely worth a look at the poppet as also very easy to remove and check (although tends to block less often in my experience).

[Big Steve 435]

I keep a stack of thermostat gaskets in my tool box for the 300xs
I have well over 500 hrs running them, as part of my regular service program, I pull and check them for debris often along with the air pump water pick up screen in the mid section
The air pump water intake screen is a must service item for air pump life.
On the early 300xs motors they had lower temp thermostats and are very desirable