96 GTI jet pump bearing or crank bearing failure?

[skrillac]

A little backstory first. Earlier in the year I took the jetski out and near the end of the day could feel what I thought was jet pump cavitation. I would rev the ski and it would have problems reaching mid speeds and higher. I could hit max rpms, but the ski would just hit maybe half speed, as if there was excessive load on the engine, then in a few seconds it'd clear up and I'd hit top speed. I definitely noticed it was present during throttle acceleration.

Today I noticed more of the same. I was accelerating out of a no wake zone, then all of a sudden I heard a grinding noise. At first I could limp over to the bank and had a bit of forward motion, but then the ski couldn't produce propulsion. I stopped/started the ski a few times to make sure I could do just that and checked to see if I had blown a crank seal, i.e. leaking oil. I wasn't able to determine the source so I got towed in. I pulled both hoses off the head (aside from the one running to the exhaust) and sat watching while I got towed. Not a drop of water came out of either hose (couldn't remember which hose to pinch).

About a year and a half ago, I rebuilt the top end of the engine and the jet pump. Jet pump was a thrust bearing replacement, wear ring replacement, and oil change only.

I'm leaning towards this being a spun jet pump bearing from the symptoms above. Would appreciate the input from anyone with experience. I'll be taking the jet pump off tomorrow to see for sure.

 

[skrillac]

So i took the jet pump off this morning and found that the pump body was separating from the ski hull. Two of the nuts and lock washers had come off and the other 2 were very loose. Now that I think about it when I was getting towed, I noticed more water in the hull than usual. I imagine the pump body separating from the hull caused that, and was the reason why water wasn't flowing from the jet pump to the block while I was being pulled.

After taking the jet pump off, I did a few engine tests to try and find the same noise I heard yesterday on the water. I've included videos of the ski with me just bumping the starter, and then running it shortly at idle (with one or two small revs). I remember distinctly hearing the grinding noise at idle when I was on the water, as well as various throttle positions. I put the jet pump in a vise and spun it with a drill, albeit the drill maxes out at 1800 rpm or so. No significant noise from that either. So I'm stumped on this one. I may just put the pump body back on the hull and red loctite the studs holding the body to the hull so they don't loosen up. I swear i put blue loctite on those before.

Any thoughts appreciated.


starter test with impeller removed

running test with impeller removed

 

[skrillac]

So i think I figured this one out. The pump body had separated from the hull. I found a slight wear of the driveshaft end on the jet pump side. Checked the impeller part. Since it was lubed well, after I cleaned it there wasn't any noticeable wear. The driveshaft still fits into the jet pump and spins without play or slipping.

I imagine what I heard was the driveshaft slipping in the impeller as the pump was breaking away from the hull. Now that I have the driveshaft and pump apart, it seems like a good time to replace the carbon ring.