My sludge tank is pretty bad like that too. I already did a thorough flush, enough that rust in the coolant drain sump no longer appears, but I think I have to do a reinspect. I want to replace the tank itself but it is bolted to the exhaust manifold bolts and do not want to mess with that. I might just set up another tank elsewhere.To circle back on this blow out i had awhile back, I found the hose on the water manifold to be fully plugged with solid rusty sludge for the 5" of hose closest to the surge tank. I'm thinking this has something to do with the pressure finding a messy way to relieve itself.
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This was the sediment I pulled out of the sludge tank with a magnet...pretty bad...
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