Impeller shredded. Less than 2 years old. Ideas?

[sydneyACE]

Hey everyone!
Details - '84 Supra Rider with Chevy 400 small-block and Sherwood belt-driven raw water pump.

(*Disclaimer* I made-it out to the lake on Friday afternoon with my new gear and a little-bit of ballast as-well, so the season hasn't been a totall failure yet. No need to feel too sorry for me.)

So on Sunday I got some people together, gassed-up the boat, and made-it to the lake.
I was pretty excited! I had 5 80# sand-bags under the ski-locker for ballast, my new board, and new rope.
I also bought 4 6-gallon water jugs to provide a little extra weight. I even convinced my brother to bring as many 5-gallon buckets with lids that he could find. (Ended-up with 4 of those.)

Long-story-short, I motored accross the lake to the far-end without problems. When we got down there, I proceded to fill-up all my water jugs and buckets. We trolled-around a little so my pops could do some fishing. After a while, he gave-up and I was ready to board. I decided to do a quick oil-level check before gearing-up and riding. When I opened the cover it seemed a little hot in there. I felt the manifolds and they were way too hot. I checked my (transparent) hoses and they were dry.

The first thing I thought was maybe something plugged up the pick-up on the bottom of the boat. (It had stormed the day before so there was some junk in the water.) I disconnected the hose from the trans heat-exchanger and blew into-it (in the direction of the pick-up) to see if I could dislodge any debris that might be clogging it. Air blew through freely and it didn't feel like anything came-out. I hooked everything back up and cranked the engine to see if it would suck in any water. No luck, the damage had been done. I took-apart the raw water pump, and sure enough, the impeller was shredded. Sadly for me, my cheap-ass was too broke to buy a spare last season and my day was over. :(

TLDR:
I ordered-up a new impeller (and a spare), but I'm really concerned about WHY the impeller shredded.
Any ideas as to WHY my impeller got toasted?
It didn't look like it got too hot (no signs of melting/heat-cracking, etc).
My theories are that something plugged-up the pick-up for long enough that the impeller ran dry and eventually came-apart.
I thought maybe it sucked something in there that physically damaged the impeller, but after thinking about-it, I find that unlikely. The slats in the pick-up aren't that big, PLUS it would have to go through the trans heat-exchanger which has even smaller holes (look to be about 3/16 or so).

So, if anyone can provide some insight as to WHY this thing went-out, I would love to know. If there's anything I can do to help prevent this from happening again, I need to do it. At $40 a pop, I don't want to chew-up any more of these things.

As a point of reference, a co-worker of mine has a 2007 Moomba that he's been running on the same Impeller since new. I know I'm not the luckiest guy in the world, but what gives? How can he get 4+ years out of an impeller but I barely got 1?

[Hematoma]

If there was a big gap between uses like over winter it's a good idea to add some dish soap to it and spin it by hand to get the veins lubed up. If the veins are dry and stuck to the inside part might tear off and mess other veins up. I'm on 3yrs with same impeller without problems. Knock on wood. lol

[lively]

usually when you winterize its good to remove the pump and store inside .. lube with soap as mentioned and store in a bag ... extra precautions will save you heartache on the water
with older style sherwood i would just remove the impeller and reinstall when its summer again .. ( check your strainer also )

[Supra-in-steamboat]

It most likely shredded because it was old. I carry some spare old ones, but always replace it once a season (50-100plus hours) with a new one. Try to find all the pieces of the old impeller if you have not already as they can travel as far back as the Supertrapps and clog up some flow. Good luck.

[Blackntan90]

The manual for mine says to remove the impeller and store it in a bag so the vanes don't take a 'set'.

[Salty87]

use makes a world of difference. the longer they sit, they faster they dry up. start em spinning like that and they will quickly fall apart.

use the boat or run the engine more often and they'll last longer.

[crystal waters]

replace mine each year with a new one! Perhaps more costly but also never any issues! Cheap insurance !

[haugy]

I always replace mine with a new one yearly. Then I keep the previous years as a spare. They are cheap insurance, and if you use your boat a lot, worth it.