Offshoreonly.com - Need some advice

Quote:

Originally Posted by FOUNTAINFAMILY

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.

You are misinformed. That is not enough pressure to give a complete fill, possibly allowing for air pockets in the heads, and possibly a higher false temp reading because the sender may be registering a steam pocket, not water temp.
Stock HP500's will have around 15-20 at WOT. Since you stated new circulating pump and t-stat, that eliminates a crossover setup which will give low pressure.

Something is blocked/not right. Double check the inlet supply hose from the transom to the sea water pump for blockage or a kink. That hose HAS to be hardwall. You can't squeeze it by hand. Also remove the hose on the outlet side from the seawater pump, then remove the hose end right before going into the t-stat housing and back flush that line making sure no broken impellor parts come out a tthe seawater hose end.
You did install the hoses on the right ports when you replaced the impellor? That will give the symptons you are seeing too. If all checks ok, check the flow from the drive pickup to the seawater pump.

Good Luck