Re: Water pump theory question

[Don]

Well, I guess I would hesitate a bit before ripping that engine apart. You mention it is a fresh water motor, looks like new, and shows no signs of overheat. So, that makes me wonder just what could have happened so quickly that would cause a no pump condition. Seems like whoever owned if before wasn’t having a problem, or you surely would have seen evidence of overheating. Did you run the engine before replacing the impeller? Did you replace the impeller just for routine service, or after you discovered the engine wasn’t pumping water.
Did you use an OEM impeller, or aftermarket? Are you running the engine on a flushette, or did you back the boat into the lake?
From what you have reported, it doesn’t seem like this engine has a messed up head gasket, exhaust cover, cylinder deflectors. I guess I would remove the gearcase, then rig up some sort of hose adapter to the water tube. Gently turn the water on without the engine running to see if water flows through the engine (overboard indicator) now. If water does seem to pass through the powerhead using this garden hose adapter (very low pressure please!), then start the engine with the gearcase off and the garden hose rig supplying water to the powerhead. I would only suspect internal leakage if water stops flowing through the engine once the engine is started while using your garden hose to supply water.
If water flows through the engine nicely with the garden hose rigged up when running, then I would suspect something is messed up with your water pump. The 79 35s came with the newer style water pump with a plastic housing and SS liner, these parts will not interchange with the original style aluminum impeller housing pieces. You could always try removing the gearcase and water tube, then installing the water tube into the pump and submerging the gearcase in a bucket of water. Now spin the driveshaft with a drill to see if water comes up and out of the water tube.
Again, I would stop and recheck several simple things before ripping the powerhead/head/exhaust cover off….I can’t help but thinking we are missing something simpler here. It just seems like too much of a coincidence that this engine never overheated for the previous owner, and has developed some major internal leak/blockage after your took ownership…
Feel free to post as many pictures as you like, that might help us spot something that is getting missed/overlooked.