ProXS water pressure/temp

[Tfootstalker]

2019 250.


Hey all, what should I be seeing for water pressure at startup idle? And am I safe to assume the thermostat doesn’t open until around 154*?
I had an overheat alarm waiting to load, thought it was just some scum that was floating around. Flushed motor and checked both upper filters. I’m seeing like .1-.3 (sometimes 0 on both gauges for a sec) psi at idle and temp climbs to 150-160 before coming back down. Doesn’t seem to get there while boat is moving. Piss stream pretty weak too.


Strangely during flushing the motor there was a groan no matter how much pressure I put through the hose. It was weird like a water vibration or something. And no water came out the nose cone intake holes, rather came out the piss stream and around the seam of the lower unit and middle.


Motor has 154 hours. I assume I should do the three year service and hopefully it’s a water pump issue

[Capt James]

I have a 2022 300R and only see 1 PSI at idle and never an overheat problem.

[RdRngR]

Really shouldn't see lower than .7. Time to replace that water pump and check the screens.

[EuropeanAM]

+1... I would recommend an impeller and gasket (be sure to use Perfect Seal or Aviation Sealer between the gasket and plate).

If you would, please take a few moments to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

[Tfootstalker]

2B634760

Update: went with the 300 hr service and replaced pump gasket. They said pressure is where it should be now, but we’re froze right till April here for me to check. Interestingly, there were 5 service bulletins four of which were just checking things and then the starter solenoid. Are these new, or were they never done by previous owner?

Also, my analog trim gauge won’t move until about 5-7 on the digital gauge. Mercury told them it won’t move until engine is level with water. What’s this about?

[EuropeanAM]

There were TWO that specifically applied to your engine engine. Others were merely informational (which is quite common). Any bulletin that requires a specific action is marked and assigned to the engine's serial number (incidentally, they didn't file claims to close the two bulletins that were showing).?.?. SB 2019-009 and SB 2019-010 show outstanding.

Also need to get the engine transferred to your name (either through your dealer or by contacting Mercury Customer Service).