Mercury 3.0 TKS how does cooling system work?

[rnorman3]

Hello, my understanding of the sea water cooled engine (Mercury 3.0 TKS) is that water is pumped up the leg by the impeller, enters the block at the thermostat housing. It is circulated around the block by the water pump. A small amount of water is continuously added and exited via the "weep hole" in the thermostat housing (see pic) and out through the exaust manifold (through pipes which I cannot see). When the engine reaches 160F the thermostat opens allowing additional cool water to flow into the block keeping the temperature in check at about 160F.

Does this sound correct?
Thanks!

 

[Chris1956]

Re: Mercury 3.0 TKS how does cooling system work?

You should post this in the MerCruiser I/O forum. Your description is very close. The weep hole likely allows the motor to circulate a small amount of water to bleed the system of air, and help get hot water to the 'stat. The engine block warms up before the manifold, and the manifold is full of water. So the manifold does not receive any water circulation until the 'stat opens. Also, as water is pumped into the manifold, the excess water is dumped into the exhaust gas stream and then overboard thru the prop.

 

[Faztbullet]

Re: Mercury 3.0 TKS how does cooling system work?

Hello, my understanding of the sea water cooled engine (Mercury 3.0 TKS) is that water is pumped up the leg by the impeller, enters the block at the thermostat housing. It is circulated around the block by the water pump. A small amount of water is continuously added and exited via the "weep hole" in the thermostat housing (see pic) and out through the exaust manifold (through pipes which I cannot see). When the engine reaches 160F the thermostat opens allowing additional cool water to flow into the block keeping the temperature in check at about 160F.

Does this sound correct?

You are correct and the water to manifold is the hose on t-stat housing to manifold......

So the manifold does not receive any water circulation until the 'stat opens.

No as it always has water or it would burn up exhaust boots and shutters...