3.0L Mercruiser Bayliner 185 Temp question

[Dhuston99]

Just had my engine serviced. Changed the plugs, cleaned carb, unstuck a valve and added a fuel filter in the engine bay, and replaced belts. Ran the boat a few times since then no problems runs great. Still running fine but noticed today that the temp gauge is showing 225. Pretty sure yesterday it was showing 175. Let the boat sit for an hour or so and as soon as it starts the gauge shows 225. I know it can't still be that hot. I can touch the exhaust manifold. Thinking it is the sending unit just wanted some expert input. Also, the alarm sounds with the key in the on position and the engine off so is it safe to assume the alarm is working? I am pretty sure I had the water pump replaced a year or two ago. Has only been in the water maybe 6 times in past few years. Any thoughts are greatly appreciated.

Thanks

 

[Scott Danforth]

Confirm the temp with an infrared thermometer.

When was the last time you replaced the raw water pump?

 

[Dhuston99]

I will check the temp with an IR when I get it back home. At the lake for the weekend. I am pretty sure the water pump was replaced about 2 yrs ago, but the boat has only been in the water 3 times since then. I let it sit for several hours, started it up and the temp gauge was reading between 175 and 200 and it climbed to 225 just sitting at idle. The alarm has never came on. Ran it around the lake twice and could touch the thermostat housing. It was warm but didn't burn me. Thanks for all the help so far.

 

[Scott Danforth]

Pur your hand on the block and head.

225 is way too hot if that is the real temp

 

[Dhuston99]

Ran the boat again. Temp was reading 225. Could touch the head and the riser for a second or two without getting too hot.

 

[Dhuston99]

Check the temp with an IR thermometer yesterday morning. Read 160 right at sending unit. Gauge read 225. Took the boat out and just cruised around the lake looking at houses I cant afford! Boat ran fine under low speed, more than idle though,. But when I tried to get up to speed the engine would rev up but then it would like the boat was slipping. It would just kinda slow down. Pull back on the throttle and it was fine. Crept back to the dock and looked at the prop and lower end everything looked fine. Drove it around for a few minutes more and it would accelerate fine. Later that day in the way to the ramp to load up it start slipping again. Any ideas what that could be? I got a new sending unit today and replace tonight hopefully.