671N- still running warm over 2,000 RPM

[newinlet]

Good morning,
I have been woking all summer on an issue with my 671N J&T that in the past simply cleaning
the H/E would work This is what I have done so far. Port engine only engine runs smooth

Replace impeller end cap and wear cam ( no missing rubber parts)
Replace thermostat
Replace heat exchanger core I found a new one
Clean strainer basket
Haul boat wash bottom check intakes blast intakes with pressure washer
Drop coolant- put water and cleaner in F/W side -take for ride with thermostat removed
Replace coolant Approx 60/40
Replace fresh water pump
Pressure test engine holds pressure- not losing or gaining coolant- engine temp follows RPM only
Pump Approx 10 Gallons muriatic acid water mix through exhaust mixing elbow
Raw water flow looks good at dock
Seatrial with infrared thermometer. confirmed engine running warm- raw water side cool
Always steam coming from this engine @ higher RPM from what I am told indicating a restriction
or raw water flow problem .
I removed the zinc @ the heat exchanger and installed a pressure gauge I have read there should be
no more than 10 PSI of pressure @ any rpm. Test shows no more than 2 psi @ any RPM
My riser is large stainless with a Monel fitting
I guess next is remove intake hose and inspect !! replace raw water pump can it be bad
Anybody ever have this issue.
Any advice would be appreciated Thank you
Forgot. flushed block everywhere possible with fresh water prior to installing new freshwater pump

 

[Pascal]

Define warm? What temp are you getting and what is the other one running at.

It could simply be that this engine is running at a higher load. It a not unusual for some engines to be running warmer above cruise RPM

 

[newinlet]

Pascal thank you ,
The engine will continue to climb and overheat,
Update, pulled off intake hose. I will replace. found lots of zinc pieces at the intake. I think this is the issue
will update later thank you

 

[Captain Ralph]

I have found bad and collapsing hoses between the sea-cock and raw water pump to cause more grey hairs than all else.

 

[newinlet]

Update,
Problem solved if I can figure out a way to post a picture I will,
Old pieces of Zinc @ the raw water pump was the issue. caused a restriction of water flow @ higher RPM
Replaced intake hose just because cleaned out the zinc stuff good as new.
thank you everyone that offered advice .
this was a month of Sundays to fix !!!!!

 

[Captain Ralph]

Update,
Problem solved

Lets go fishing...