Wait. Do you think 180 is hot? Thats not hot. Thats normal. I see over 200 when running hard with 496's

No Sea Strainers are on the boat.

Serial # is : OW628151

I'll check the power steering cooler for sensor. I ran the scan tool at idle, and the gauge matched the scanner.....but the Rinda didn't show a water pressure parameter ??

The motor has always run in the 170 range while running. Now after running through mud a few times I'm at 180+ (needle sometimes creeps past the 180 mark if I'm running near 4000rpms. I know 190 is guardian mode, and I have some room to 'grow' but I'm trying to figure out why its no longer in the 170 range.

I did notice last year while winterizing that the blue air pump did not pressurize the system to pop the valves and let the water out. What are the chances that the water pump is sucking some air from a leak somewhere in that system ?

Running in the mud routinely will make a mess of you pump housings quickly I would think. Your recent impeller and plate change might have lost efficiency and now your temps are creeping up. Water pressure is definitely monitored, but why you don't see that on the Rinda, I have no idea. That parameter should be in there as it shows on Smartcraft readings.

If the quick drain valves didn't open when you pressurized them, chances are they are stuck closed and not a source of a air bleed. If they were open you would have a massive amount of water dumping into the bilge as soon as you started the engines.

I'd lean towards the mud running being part of a drop in pumping efficiency and it is manifesting as higher temps. Until you get a alarm, I wouldn't assume you have an issue just because it is running hotter than before.

Running thru mud is a no no. I would backflush the seawater side of the cooling system. Start at manifolds, HE, oil cooler, ps cooler, water pump. Flush each piece individually. Then go from there.

check valves - I would replace them anyways being at least 10 years old.

Possible your actuators drains are plug to not drain water. I would pull all blue drain plugs and stab those holes to see what drains out with water

before anyone says what in the hell how can check valves cause hotter running conditions - the jist not writing a book here - one is if restricting water flow - this will back up water and or slow down water flow causing a hotter running engine. Also restricted check valves - One way valve can also not make all the water drain out when using the air actuator or pulling blue drain plugs.

fluctuating temps can be a sign of aerating water flow - a scared impeller housing can also cause aeration of water flow. ie: cavitation

Also a bad water circ pump causes fluctuating temps. Also a t stat. Also worn out anti freeze. I totally understand this a closed cooled app. I am posting extra info for whomever and possible other causes about your app that would not be thought of.

Which check valves are you referring to ? where are they ?

I pulled the 4 blue plugs that I know of (2 on seawater pump, and 2 on the opposite side), and water flowed freely. No debri anywhere.

Are you getting any water in the bilge when running?
I think BUP is referring to the air actuators that allow water to pour out when you apply air to the schraeder valve (to light-winterize). They have springs in them that can and do go bad over time, and will allow water to pour out of them at higher RPMs. This could be your issue as well.

Also, do you have a fresh water flush system hooked up? Are there any valves, check-balls, or any points where debris could be stopped up in that section of inlet hose from the transom to the SWP?

just an example but not your exact serial number run but earlier versions - you should have a one piece that could have the check ball - we call them check valves and or check balls.

in the pic number 28 and 29 just an example as again you could have the 1 piece version.

http://www.marineengine.com/parts/me...lbow-and-riser

and yes as Brian said make sure your air actuators are not leaking water - the one behind the water impeller housing if it leaks will surely reduce water flow and reduce water flow to the impeller housing.

If the engine is stock than 200 degrees is really concerning and honestly should be addressed if truly accurate. The waning horn should be sounding off right around 196 degrees I believe this one to be preprogrammed at within the ECM as Merc has a few temperature ranges for the waning horn.

In the following link, sensor item number 7 is what the PCM reads for engine temp while sender item numbers 8 is for the temp gauge, http://www.marineengine.com/parts/me...ter-components