No Thrust, Water in Hull

[Skyhawk76E]

Still going through the break-in process for my new SBT engine and hit another problem with this "bargain" ski...

It's a '92 GTX. I took it out for the first time in the water to do the "up to 20%" break-in. I had to travel down a 1/2 mile channel out to the river. The ski initially had lots of thrust and would hit 20mph on my handheld GPS pretty quickly. After about 10 minutes the thrust vanished even though the engine ran smoothly.

There was enough thrust at idle to travel back down the channel to the dock.

When I removed the seat I could see a lot of water in the hull. After getting home I found that the protection hose was off the seal carrier and all the way up against the PTO coupler. I'm new to Jet skis so I'm at a bit of a loss...

Where did the thrust go and how do I get it back?

Where did the water come from and how do I get rid of it?

Thanks!

[Technical Support]

some of the thrust came thru the seal and also make sure your impeller is in good shape. if you know your engine is running good with good compression then you need to fix the original problem with the seal and then go from there.

[Skyhawk76E]

The engine is awesome thanks to SBT. The impeller blad looks real good to me, and as I said it was producing great power.

I found that the shaft had apparently moved forward from producing thrust, puckering the PTO coupler seal in towards the engine. Apparently this took the protection hose forward with it (not tight enough?).

I wonder now if I'm missing one or both "plug bumpers" from the shaft. I don't recall seeing one when I removed the engine to replace it.

Would that cause the lack of thrust?

Thanks!

[Technical Support]

It would if the shaft slid and striped out the PTO and/or impeller splines. You NEED the bumpers, and if you damaged the splines you need to replace the parts.

[Bill O'Neal]

You lost your thrust when the beraing carrier moved forward allowing the pump to suck air from within the hull, down the driveshaft and into the pump. Fix the bearing carrier/protection hose and try again. The water entered the hull through the driveshaft thru-hull fitting that the protection hose and bearing carrier seal off when they are properly installed and the clamps are tight.

[1fastski.com]

you might find that the carrier was stuck on the drive shaft and it spun and melted the though hull fitting , if so they sell a insert for it . replace the carrier bearings and grease it every few rides :)

[Skyhawk76E]

Just an update for future readers...

Bill was right. I took the ski out today with the seal clamped back in place and it ran like a champ for the next 30 minute break-in session! It must have been sucking air into the pump under power, then allowing water to flow-in through the same seal gap when the pump was off.

THANKS!!