Exhaust Manifold blockage? Manifold bypass option?

[Linguistine]

Hi - regarding a Lister STW2
I have been searching for a blockage in this direct cooled engine for months and I 'think' that I have finally traced the problem to the feed through the exhaust manifold, a pipe runs from the thermostat to the manifold, through it and out the top and via a rubber pipe into the exhaust elbow. I have tried blowing through the top and bottom of this pipe and there is no flow, I currently have some Rydlyme filled to the top in a funnel/hose attached to the top of the manifold and there is pretty much no flow through, maybe a drip every hour. I want to check that this is the issue - I would have thought it would pour through from either way?

I have been told that I can bypass the wet exhaust and run the manifold hot - any thoughts/suggestions here most welcome.

Or, perhaps I should get the manifold taken off and soaked properly - it could be filled with sand etc? The set-up doesn't have a modern type of strainer just a cylindrical 'colander' in the seacock.

 

[colind3782]

May be of assistance?

https://www.winget.co.uk/document/LISTER ST WORKSHOP MANUAL.pdf

 

[vyv_cox]

I don't know your engine but removal of the exhaust elbow for the purpose of digging out carbonate salts is a very common practice on most marine engines. Chemicals will do it eventually but it is far quicker and more thorough to do it off the boat. Take care with sharp tools such as screwdrivers as these can easily penetrate cast iron manifolds that have been weakened by corrosion.