Port e-top header exhaust boot burnt through twice
 

I have 4 hrs on my new 540 efi, two weeks ago I found black on my white swim platform that is directly below my port exhaust tip. I pulled the plugs thinking it was running rich, but plugs looked perfect. Went back to the water only to immediately burn through the boot between the header and tip. I brought it home, pulled the Outdrive and put a new seal kit in after finding a damaged o ring. I ran the boat for 20 min around table rock lake and burnt through another boot. I have back flushed every hose and cooler on the cooling system, and checked the veins on the sea pump only to find nothing. I tried tightening my serpentine belt, and took the boat out. Upon startup the port side starts shooting water out about 3 sec later than starboard, but have the same amount of flow at idle. With the boat on plane for a cpl mi, port side flow is next to nothing, and the tailpipe reads 50deg hotter than starboard. The bottom water rails on the headers are plumbed to the thermostat housing w 1" hose, the thermostat has a 140deg with 3-1/8" holes in it. The thermostat housing's two ports set 90deg apart, and also has two temp probes in it. The motor always runs at 150deg. I am obviously overlooking something, but still don't understand why I'm running out of water on the port side while I'm cruising.

sounds like you have some blockage some where. can you swap your hose from side to side to see if it does the same,

i have a 496 mag ho in my boat. The previous owner installed a ball valve just before the starboard side water rail to the header. It helps redirect flow to the port side headerby closing it very slightly. Sitting at idle i can actually feel the difference in temp on the tops of the headers with the valve wide open to the valve being slightly closed on the port side header.