Hello, I have a rebuilt 454, problem I’m having is when I first start it, I pump good amount of water out of both sides, as the engine runs I lose water flow to port side of the boat. This is running on the hose! I’m wondering if I’m not getting enough water to the engine! Reason why I’m thinking this is I’m not seeing no water come between the muffs while running but it just dumps water out of the starboard side like the port side is starving for water!

pulled the hos cap off the riser while running and water does pour out! But not out the exhaust
new water feed tube, new bellows
idk what other problem it could be, other then not enough water from the hose off my house!
also has a new raw water pump

Ayuh,...... That's entirely possible,..... Have you changed the raw water pump impeller,..??

Another thing,..... Is the motor Dead Level,..?? if not, you'll get more flow from the lower side,....

engine is level, new raw water pump!

Its common and pretty normal to have less water flow from port exhaust side at idle. As long as the exhaust is staying cool, it is fine. You have more water at cold start up, because the TStat is closed and all the water is bypassing the engine.

I have ran my motors off a 300 gallon water tank when they were out to test, you would be AMAZED at how fast it will drain that tank. My motor guys has always hammered into me when flushing ,,,water flow, water flow.

On my dock I use the large 3/4" industrial hose to flush, and will soon feed them with 1 1/2" line all the way from the meter.

Doesn't surprise me that with a set of muffs that don't seal well on the drive you may not have enough flow, I would not rev the motor at all. What size hose?

Ya, I was gonna say did he find all the veins of the impeller?
I would start with pulling the feed line from the thermostat housing and putting a garden hose in it on high. Any resistance and you have a blockage somewhere.

The water hoses to the exh can partially kink making sharp bends if not using the factory type hose. Also if you have silent choice type exhaust, most of the water goes out to the drive area even with exhaust set to "loud". Mine has been doing this (on both engs) since I've owned the boat. I've used an infrared thermometer to compare manifold/riser temps and they're both abt the same.