Thread: F100: Did I find something here?

Some of y'all may know I'm working on an F100 Yamaha engine that supposably locked up after overheating on it's previous owner. And that was a couple months after that previous owner had the engine rebuilt.

Anyway, I've replaced crankshaft bearings, and have had a difficult time getting it running. While doing so, I've run it briefly, and I've compression checked it, all while out of water. I didn't think it harmed the impellor, but I was wrong. I opened up the water pump and found this:



I took it apart, and was ready to install some new pump parts. And then I came across this (ignore the metal cup thing which I mangled removing it from the housing):



In the first pic, there is no gasket between the steel plate, and the impeller & it's housing.

In that second pic, that green gasket was found below the steel plate. I think that's wrong, that specific gasket belongs above the steel plate, and the housing.


The correct gasket for below the steel plate is pictured below (I already put it in it's place), and not the one I'm holding in my hand. When the one I'm holding in my hand is placed under the steel plate, I believe there's a gap then, which allows the impellor to suck air between it's chambers. Which makes for real poor pumping water action!!! Tell me I'm wrong?



Could this have added to this engine over heating on the previous owner.

Plus, when I did first start the motor after I put it together (when it was running poorly), I did run it in water, and I don't remember it peeing water out the pee hose. hmmm