On my Westerbeke and most other diesel engines the exhaust injection elbow is bolted directly to the exhaust manifold. This measurement is how hot the actual dry exhaust gasses are.


As you can see there is about a 100 degree drop in exhaust gas temp after the water injection. This reading is a little low for my engine but again this was for illustrative purposes and the temps on my engine mean nothing for your engine.


If this measurement and differential temperature between the wet and dry side begins to get progressively wider and hotter and hotter it' a good indication you have an injection elbow beginning to clog.