Mercruiser 4.3l V6 cooling pipe…

[OceanRipples]

Hi all, I’ve just winterised my 4.3l V6 Mercruiser and filled the cooling system with antifreeze. When squeezing one of the larger pipes, I felt a crumbling/cracking within the pipe. Which didn’t feel too good. Is this likely salt within the pipe do you think? I’ve highlighted the pipe I’m referencing… does anyone know what this pipe does/ where it feeds etc?

 

[spannerman]

That is quite normal as the pipe has a spring inside to prevent it from collapsing as its on the suction side of the circulation pump, its the spring moving that you are feeling when you squeeze it. It takes water from the thermostat housing down to the circulation pump which tries to feed it into the block, it can only do this when the thermostat opens allowing hot water to escape from the top of the engine being replaced by cooler water from that big hose, then the thermostat closes and the cycle repeats, the released hot water then flows to the underside of the manifolds and then up through the risers and out. The two hoses on top at the front supply constant cold water to the risers so they don’t get too hot, it should be possible to keep your hand on them, if not then the flow is restricted.

 

[OceanRipples]

That is quite normal as the pipe has a spring inside to prevent it from collapsing as its on the suction side of the circulation pump, its the spring moving that you are feeling when you squeeze it. It takes water from the thermostat housing down to the circulation pump which tries to feed it into the block, it can only do this when the thermostat opens allowing hot water to escape from the top of the engine being replaced by cooler water from that big hose, then the thermostat closes and the cycle repeats, the released hot water then flows to the underside of the manifolds and then up through the risers and out. The two hoses on top at the front supply constant cold water to the risers so they don’t get too hot, it should be possible to keep your hand on them, if not then the flow is restricted.

I’m very grateful for your reply and sharing this knowledge! So insightful and helpful. Makes complete sense and a relief to know it’s normal and I’ve learnt more about the cooling system. Thanks!! ??