The elbow was the first thing I checked and was perfectly clean. Maybe I need to try to check the rest of the exhaust somehow. It may involve cutting it out and replacing it just to see if it is ok.
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the reason I took the video is to show just how much force a clean exhaust system has to expel the exhaust and cooling water.
That said ... black smoke is generally badly burned diesel ... does low compression also give badly burned diesel?
another symptom we had was that black smoke also backed out the air filter as the engine died ... but you are not at engine dying stage yet? we don't use filter element in air filter ... think those filter gizmos were for operation in desert sandstorms.
I was able to take the exhaust hoses off on Saturday and they were in great shape, so the exhaust is not the issue. Last thing to check is the pump and cylinder compression, I think.
