mikeoutlaw24

i have a 350 horizon with low water pressure on the port side exhaust tip,the right side has a lot of pressure.i put in a new sea water pump,clean out the heat exhchanger, back flushed,took the risers off and new gaskets and flush them with the hose and had good flow . the riser have the open gaskets ,should i put a restrictor gasket on the right side to get more pressure on the port side . need help thanks mike

lakematdude

I would not recommend just putting in a restrictor gasket at this point without checking and confirming the way it supposed to be done by the service manual.

What is your Mercruiser engine serial number? Being an horizon, you have the closed cooling system correct?

What is the height of the risers, 1.7 inches, 3 in, 6 in ???

MEANGREEN231

If its stock exhaust check the checkball assembly in the tstat housing, I have seen them wear a ridge in the plastic ball then get stuck and then that side only gets bypass flow. Otherwise time to check the manifolds and risers for rust scales that are blocking passages.

mikeoutlaw24

it was the end cap gaskets on the heat exchanger they were bad thanks mike

Gun Slinger

I just went thru a similar issue. Try disconnecting your hoses that lead to your manifolds from the thermostat housing and see if you can get your pinky finger into the thermostat hole. I had so much fresh water corrosion that I could get the tip of my pinky in the hole. I removed the thermostat, and using a dremel with a grinding/sanding bit, cleaned all the corrosion out every port. It came off like dried dirt comes off with a hose, took me 15 minutes, and needs little effort. When I was done, half my middle finger fit in there!!! fixed my flow problem completely.