Riser Gasket Question, Urgent!

[kx250frider617]

I was just working on the boat today, installing my new manifolds and realized I now have the restricted riser gaskets that were included with the kit. My old ones were open-style. I did some research and found out Mercruiser changed some of their stuff in 2001, when my boat was made. I have the Mercruiser 350, raw water cooled engine.

http://www.boatfix.com/merc/Bullet/99/99_10.pdf

I find their description to be very confusing. Right now, the raw water goes into the thermostat housing and it then distributed to the block, the manifolds and to the water pump. This is all before the water even gets to the thermostat. Going from this new Info, It seems like I should have the restricted gaskets, However the OE was open. I already have the restricted ones installed (haven't started the boat yet). Can some one clear this up for me? I would normally just get the OE but I already have the restricted ones, and it seams like mercruiser changed it also.

[dom w. forte]

When you say restricted are all the slots blocked or just one , or do you have the round holes with one smaller size?

[boatwakes]

You should go back to the open style, the restricted are for use when the engine has a separate hose going to the riser from the thermostat housing as well as the water feed hose to the bottom of the manifold. The system (full flow not restricted) is designed to flow water at full strength through the manifold when the thermostat is closed as well as open.

[kx250frider617]

Okay that makes sense now. I have the two slots with two little holes. I tried cutting them out with a razor blade but there is some hard material. I also noticed my thermostat failed and is stuck open. It it has probably been like that for awhile and I haven't had any issues. Should I even replace it? It is ran in salt and I bet The thermostat is corroded stuck inside the housing. Maybe its best to just leave it rather than go through the hassle removing it. Also, another note, My thermostat housing looked pretty bad. I looked at the prices online and they are $250. No Way! I just cleaned up my original and re-painted, but like I said, that thermostat is stuck!

[kx250frider617]

Just finished it all up, I actually found this product called Metal Rescue. I drained out the water in the block. (Smelled like S**T), Removed the thermostat housing, and poured 2 gallons straight into the block and water pump) It sat for a day. The stuff is non- acidic and environmental friendly. It just attacks the rust only but also darkens the metal. Its safe on rubber etc. Anyway, put everything together and just started the motor. NO LEAKS!!!! let it run for 20 min and black soot started coming out of the exhaust (All the decomposed rust). Then it cleared up. Now my cooling system is the cleanest its been in years and it was a nice little project.

I also, went a bought the Open riser gasket.

[dom w. forte]

Highly reccomend new thermstat , you need proper temperature and even temp across the block.

[boatwakes]

X2 on the thermostat. Replace it so the computer stops overfueling because you're running too cold.

[kx250frider617]

I was actually looking at the housing upside down. When I run the boat, it warms up in a few minutes and stays the temp the whole time. So I think it is actually fine. Does anyone have a picture of the thermostat inside the housing?

[boatwakes]

Pointy end up or the side that says "this side to radiator".