It was like this when I bought it back in 2006 I never had a performance boat before so I nevr knew what the water pressure was supposed to be at. It has roller rockers, MSD ignition, Arizona Speed marine ECM Lighting headers. When running WOT the water temp gets to bout 178 while running. Monstaa good to see ur still on the board. BTW it is a 502 MPI.

yes... it depends.
I tried an IMCO shorty and water pressure drops below 25 with positive trim which sets off a fault and kicks into guardian mode.
Merc says the 600sci needs 25-45 with 30-40 ideal.

Would that be the same for my 575sci?
Rick

Don't know. If the 575sci is not closed cooling that may dictate other requirements. I called merc to get the skinny on mine.

no so cal. the 575 doesnot have the same monitoring abilities as the late model equipment from merc.

the psi may be a litle high for an mpi.
look thru the cooling system for obstruction in spots that would seem obvious so over looked. then in the not so in yur face areas. being thorough will yield great results. like makeing sure a 1 inch bung isnt 1 inch od with 1/2 inch id. stuff like that builds pressure causeing high pressure, which will make for airation in the cooling system and improper levels of heat saturation.
coolers, stats, small hoses on exhaust are an easy start, and help make fr good maintanance.

and thanx, i get busy sometimes and get pulled from the board here but i manage to rteturn.

good luck

I changed my T stat even drilled 3 3/16 holes in it. No change in anyting. I did notice that the hose from the T stat housing to the circulation pump is hot also the hose to the header on the same side (starbord) is hot also. Any advice on what to check? Could T stat housing be bad?