Flushing Coolant Channels

[SV Hope]

Hi,

Whilst replacing the thermostat on my W40 I noticed some "crud" & sludge in the cylinder head. I would like to flush this out before I put in the new coolant. Would a radiator flush (from an auto store) or CLR be appropriate for the job? Any advice for a newbie would be appreciated. Thanks.

Regards

Michael

[PeteW]

Yeah, I'm not sure what that sludge is. I have some jellyfish  like substance that will clog the smaller passages, like in your heat exchanger. Radiator flush IMO would be a good thing to run in there to descale all the rust in the block which may be the result of years of not using a proper rust inhibiting coolant.

The big problem is how to you flush the block without that toxic stuff winding up in your bilge or worse yet pumped overboard. Those little petcocks are not capable of carrying out all the rust and sludge. You need to pull lower hoses so you get a real gusher and collect that waste water in buckets.   

I opted to changing my coolant every season with the hope that it will clear up.

Pete