I have a johnson 1981 15hp j15ecis that runs fine, I just have no water movement. water pump, impeller, tubes are clear, water intake is clear. One shop told me the next thing to check is the upper water tube grommets. Looking at this exaust housing diagram, it is part number " 0324045 GROMMET, Upper, water tube" It is number 39 on the diagram off evinrudes website. There is oil on the water tube, so I suspect these gromets have deteriated. What is the best way to approach replacing those? Does the whole power head have to come off to get those or can the lower exaust housing allow access? Anyone attempted this before? I realize this is a lot of work, but I just can't figure out why water will not flow.