Maybe I'm paranoid, but temp goes to 170 Deg. F. on plane. Too high, right? 2.5L Merc

[JL Sargent]

OK, so I'm just watching the temp gauge on this fresh rebuild. I don't want to cook it right of the bat ya know. I'm keeping it below 3500rpm (30mph on my boat) during this break in period and my max water pressure at that RPM is about 8 PSI? Temp gauge is reading about 168 to 170. If I drop it back down to idle and in neutral temp back down to 140ish and water pressure is a measly 3psi or so. Should I be concerned?

I have installed new water pump, Tstats, verified poppet clean and working properly. Checked spark plugs and they still look new after two hours of careful running today. Anyway, I fell like this water pressure is on the low side. I'm temped to back flush it all and buy another empeller for another try at this pressure.

Any thoughts on these numbers?

[whipper]

i would say a little high yes. Try going faster and see if the temps cool down. 30 is a bad speed for my 2.5. Its working to hard that slow. Try and get the water flowing going 50+ and see if the temps cool down. If the lake waters warm 30 on mine isnt happy at all. Idle sucks to for to long. Because the temps come down at idle thats a good thing. Because idle should be the worst for temps as the cooling water has the least amount of flow. i would think your just at that speed to avoid maybe. BTW on what hull? 30 has a lot of hull in the water no matter what hull. Lots of drag and the motors LWPickups are at a bad angle to injest the flow also I think. Geter up and running you wont hurt nothing unless the temps dont start dropping. We drove my fresh rebuild pretty hard just vairing rpm is all and dont hold wot long up and off. Mines steel sleeve mind you but Ive got close to 1000hrs and running strong at the moment:]

[JL Sargent]

Ya know, I didn't even consider that I might be at that "wrong speed" thing. The hull is a '92 model FXD 20' Procraft 96" beam, 200hp 2.5L. You might be right. Another 10 or 15 mph might of made it happier. I did trim it up just slightly but 30 mph is about the slowest this boat will go and stay on plane. I bet your on to something with that, thanks.

[whipper]

I know mines like that. It hates 25-30mph. Faster no problem. Idle no problem for while. I would try that before I start worrying about it. things are pretty tight new so ya might need a few good rips to loosen things up a bit. Just make sure ya got double oil in there for the fist tank any way. I always run a little more oil for longer runs wot. If you have oil injection still just add a quart or so in the fuel tank on top of whats in the oil injection tank.

[STV_Keith]

Is that head temp or water temp? If you have the prop height up pretty high, slow speeds on plane are the hardest for the gearcase to get water.

[JL Sargent]

That would be head temp off the port side. I believe its temp sender off port side and alarm is off the starboard on this engine.

[STV_Keith]

While still a bit hot, I don't start doing anything with head temp until it hits 180*. I do see this at idle with my OMC's from time to time.