Thermostats

[Daman858]

Folks, I had a problem with my F200 Yamaha on a 208 Adventure overheating. I would run it for about 25 minutes at 3500 RPM and my alarm would sound and the engine would cut back to idle. I decided to check this out myself. I replaced the water pump impeller over the winter and now tackled the thermostats. Following the instruction on http://www.simyamaha.com, the job of replacing the 2 thermostats went without a hitch. Total time was 90 minutes with a few breaks for beverages in between.

Here is what the old thermostats looked like. My boat is run in salt water or brackish water here in coastal South Carolina. There is a lot of sand that gets kicked up in the shallows around here. I never ran aground or even remember my prop hitting sand as I watch my depth finder religiously and stay within the channel markers. My engine has a little over 200 hours. The thermostats in the photo looked a lot worse when I pulled them out but the sediment started to fall off when I put them down on my tool tray. I cleaned out the thermostat housings and made sure the mating area was clean and reassembled. Did a complete flush out and ran the boat for an hour at 3500 to 5000 RPM with no problems.

Ya might want to check yours if your boating environment is similar to mine.

 

[bayrat]

Seems fairly ugly for 200 hours. Do you flush the engine after each use?

 

[Daman858]

I will now. Problem is the marina hoses have the nozzles on very tight to prevent theft. Got me a pair of vice grips aboard now just for that.

 

[ahill]

Looks like good old southern red clay in them.

 

[grady23]

what did the inside of the head(s) look like??? If they as bad, your likely going to have problems down the road sooner than later.

 

[HMBJack]

I flush all the time (boat in ocean salt water) but they still looked cruded up at 400 hours (F225). Not bad, but certainly not good. Not sure how you can totally avoid it. If there are any proven ideas, please share. Thanks,

 

[g0tagrip]

Even though I flush my engines with salt away after each trip I still replace thermostats at 200 hours. I run well offshore and don't want any issues.

 

[Tucker]

I run mine in a tub with Salt Away for a total of about 30-minutes every Fall with the boat on the trailer. I decarbon the engines and fog. There's always a good bit of crude in the bottom of the tub when I'm done. I got a plastic 55-gal drum and cut the top off with a sawzall. Yea, it will fit, just have to bend it a bit.