White crystals in exhaust/cooling system?

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   I pulled my starboard exhaust riser today to inspect the internal condition of the exhaust hose. Noticed that the inside of both the manifold and the riser is dotted with what looks like little white crystal like deposits. It rubs off easily, so I suspect it is limescale - or is it potentially something more serious?

I recently converted my boat from raw water cooling to fresh water/semi-closed cooling. After noticing the coolant appearing quite rusty, I drained the block and pulled the thermostat today to do a proper flush of the whole system. The lower thermostat housing is also dotted with white specs - looks very much like the same substance in the exhaust manifold and riser, just wet. I can understand limescale deposits in the manifold/riser from brackish raw water evaporating, but the thermostat housing has only ever seen anti-freeze/coolant since I converted the cooling system. How on earth would limescale get in there?

Thanks for any thoughts/advice!

Manifold:

Riser:

Lower thermostat housing:

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
Wilhelm Hertzog Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Senior Member Joined: June-14-2014 Location: Cape Town Status: Offline Points: 334	Post Options Post Reply Quote Wilhelm Hertzog Report Post Thanks(0) Quote Reply Topic: White crystals in exhaust/cooling system? Posted: June-21-2020 at 4:51pm
	I pulled my starboard exhaust riser today to inspect the internal condition of the exhaust hose. Noticed that the inside of both the manifold and the riser is dotted with what looks like little white crystal like deposits. It rubs off easily, so I suspect it is limescale - or is it potentially something more serious? I recently converted my boat from raw water cooling to fresh water/semi-closed cooling. After noticing the coolant appearing quite rusty, I drained the block and pulled the thermostat today to do a proper flush of the whole system. The lower thermostat housing is also dotted with white specs - looks very much like the same substance in the exhaust manifold and riser, just wet. I can understand limescale deposits in the manifold/riser from brackish raw water evaporating, but the thermostat housing has only ever seen anti-freeze/coolant since I converted the cooling system. How on earth would limescale get in there? Thanks for any thoughts/advice! Manifold: Riser: Lower thermostat housing:
	1982 Ski Nautique PCM351W RR II Velvet Drive 10-17-003 1:1 II PerfectPass Stargazer Do not go gentle into that good night. Rage, rage against the dying of the light.

White crystals in exhaust/cooling system?

About CCF

Donate

Partners

Contact