Hey all- been having some cooling issues with my 500EFi's. Backflushed the oil coolers and got a fair amount of junk out of them (old impeller pieces, etc. ). Water pressure is about even now port and starboard (20ish psi at 4K). Biggest difference now is that the port engine seems to run hotter. Never sets off an alarm or anything. The odd thing is, that when the engines are off- the port gauge always sits about 1/8" above the needle rest, where the starboard gauge always rests on the pin when off. Once up and running, the starboard engine rarely gets above about 165 deg, even at wot. The port is always warmer, running about 170 at cruise and warmer at WOT, but never sets off a buzzer. Is it possible that the gauge simply being off is giving me these readings, or possibly still crud in the port oil cooler? If I have to take the oil coller off, what's involved with that? I assume there are oil lines that have to be removed in addition to the water lines- do you have to drain the oil pan to do this without making a mess in the bilge? Thanks for any input!

Switch the wires to the gauges and see if the readings reverse.

good call- will try that this weekend. Any input on what's involved with pulling the cooler to make sure it's clear?

I would swap gauges as said. That or use and infra red temp gun and compare readings in various locations from one engine to the other. Probably a bad gauge though.
The high water temp alarm won't go off until about 200*