New Merc owner & question

[Bama361]

After years of fighting Evinrude gremlins (the last one was fatal) I am now happily in the Merc family. Long story short, when my evinrude blew I planned on repowering my 361 Ranger with a 175 four stroke and thought I would be down for several months. Went and talked to one of our local dealers about getting it on order, after telling me it could be a year wait he mentioned that he had a new in the box 150 ProXS two stroke and would I be interested in it. After thinking about it for about a half second I said hell yes. I got it put on, added a smart craft gauge, and followed the break in procedures exactly. My question is concerning the temps showing on the smart craft, they seem to fluctuate wildly. I always let it warm up to at least 120 degrees before running it in the mornings and it seems to come up to 120 degrees at a pretty even pace. When I’m graphing or just idling around the temps will fluctuate from 140 to 180 just back and forth and when I jump up on plane it will drop to about 90 very quickly. Today’s surface water temp was about 53. Is this normal with this engine, I’ve not had any warning beeps and it seems to have a strong stream of water coming out. Thanks for any help.

serial number-2B528766
model number- 1150P73EV
prop- 23 Fury
hours-25
water pressure- 5 at idle 15 at wot

[leonreno]

All seem pretty normal except maybe the 180 at idle, they do normally fluctuate as the thermostats open and close but not sure if upto 180 is normal, but someone who knows the exact specs of those thermostats/motor should know.

[EuropeanAM]

+1... 180 is a bit too high for that engine at idle. Recommend replacing the water pump IMPELLER and GASKETS (3) before doing anything else (should have been done before placing in service, also due at once-per-year intervals (more often if you reach 100 hours first).

[Bama361]

Thanks a bunch

[SilverFox579]

Step by step procedure for your engine, with pics and torque specs, in the FAQ at the top of the forum. I highly recommend a genuine Mercury service manual for your engine.