I have a 1997 35 Lighting with 500HP's.
The starboard engine over heats. It cools off at idle but when ever running over 3000RPM is creeps up and eventually over heats.The actions I have taken have been
1. New Impellers
2. Reverse flushed engine
3. New Water circ pump
4. New thermostat

what next? it is still over heating, I noticed that the water pressure guage shows low pressre. Does anyone know where this guage is in the system???

Thanks and best regards to all

Did you post in the tech section? You will get more replies there.

Have you ever fried an impeller on that engine? Sometimes the pieces can clog up the cooling system and cause overheating long after you have put in a new impeller.

StarLoone

Water pressure is taken off the block. What is your pressure when crusing 3000 rpm? Does it go up when you go faster?

I am reading about 4 (PSI I assume) on the guage and around 8 to 10 on the Port (which is running between 130 and 148 degrees...

You should have 18 - 20 lbs of water pressure at wide open throttle. What kind of water pick-ups do you have? Are they the stock Bravo side pick-ups or is there a factory nose cone with a water pick-up on the torpedo? When you are in neutral and raise the engine rpm what kind of pressure do you get at 3000 rpm?
Dan

I was told that Merc. only needs about 3 lbs of pressure to cool properly. My guages read 7 on port at 3800 and 12 on Star. The drives have the low water pic-ups.

Oh and i am reading 150 degrees at full on both sides

Hey Fountainfamily what are you doin saturday Im headin out to the delta so just seein if you might be takin that new Fountain out.

I had the same problem a few years ago. Check the threaded inserts that hold the short hose going from the outdrive bellhousing (what the drive bolts to) into the boat. There are two bolts to remove the housing inside the boat to check this insert. The insert inside the boat had collapsed on my boat and was restricting flow. I eventually found it by backing the boat in the water enough for the drives to pick up water, started both engines, throttled it up and witnessed reduced water flow out of my port engine above 3000 rpm. If this is it, it is a relatively easy fix, although you will need a special tool to install the new inserts. I got mine at a local Mercruiser dealer.