1995 Polaris SLT 750 Starts, Runs, But Doesn't Move

[OhSnap]

Hi, We just bought a used 1995 Polaris SLT750. The guy we bought it from said it was going to need jet bearings and seals by next year. We got it home and put it in the water but it doesn't move at all. There is noise and vibration from the rear of the machine. I called the seller and he said the bearings must have just let go. A coincidence i'm sure

Anyone have any idea if the bearing would cause this?

Keep in mind I am mechanically inclined but know nothing about jet skis or jet props.

Thank you!!

 

[erie_guy]

Knowing nothing about Polaris jet skis, I offer the opinion that the engine and jet pump are not connected. The coupling device between the two jet ski components may have failed. Perhaps a keyway or connecting bolt(s) have failed. Attempt a test to visually verify if the impeller rotates when the engine cranks. With the boat on its trailer, look up water jet exit, perhaps with a flashlight, to see the impeller (propeller). Pull the spark-plug wires off the plugs (so the engine will not start), crank the engine over, and see if the impeller rotates. If it does not rotate, inspect the coupler at the rear of the engine to see if it rotates. Try to determine why the impeller and coupler are not rotating. You may have a broken crankshaft, a broken drive shaft, a failed coupler, or other failures along the drive train.

Could be a major repair or a more simple replacement of the coupler.

Best of Luck.

erie_guy

 

[OhSnap]

Hi, Thanks for the info! We ran the jet ski in the lake again and gave it a little more throttle, at that point it moved but just a little bit. I looked at the crankshaft coming out of the back of the engine and it is spinning, there is another shaft connected to the crank and that appears to also be spinning but only a little bit, definitely not the same speed as the crank.

 

[slag]

Your coupler is toast. the splines were probably not greased and have dried up and are smooth. You will need to pull the driveshaft and inspect the splines and also pull the coupler as well.

 

[Scott Danforth]

and while at it, probably replace the bearings and inspect the pump and impeller

 

[OhSnap]

Your coupler is toast. the splines were probably not greased and have dried up and are smooth. You will need to pull the driveshaft and inspect the splines and also pull the coupler as well.

Ok, so all this is pulled out from the rear I assume? Thinking we should take everything out from the rear right to the end of the crank then.

 

[BlueFishCrisis]

Remvoe the e clip that holds the reverse lever to the reverse bracket, disconnect the steering cable with two 7/16" wrenches, then remove the four long 1/2" drive jet pump bolts. Remove the nozzle, then pull firmly on the pump stator to pull it free. It may be on pretty tight so you might have to tug pretty good on it. The drive shaft simply presses into the impeller and coupler. You will need to perform the rope trick to remove the coupler from the motor. Check to be sure the impeller still spins freely in the pump stator. It may have seized causing the drive shaft to stop and strip out of the coupler.

 

[OhSnap]

Thanks for the info! We pulled it all apart and see the driveshaft splines are chewed up pretty good. We attempted to get the coupler off by loosening the set screw but I guess we will need to learn the "rope trick" to get it off so we can inspect it. As you suggested we are also concerned about what caused it to happen. The impeller seems to be spinning ok, the driveshaft pulls out of the impeller an inch or so so I can see the first set of smaller splines on the impeller end. Not sure if that's normal or not.

 

[Scott Danforth]

rope trick: http://www.greenhulk.net/forums/showthread.php?t=96039&page=2&p=1105423#post1105423

 

[OhSnap]

Perfect... Thanks!

 

[OhSnap]

Getting ready to do the rope trick. Got new rope just waiting for my truck to come from the shop as I left all my good tools in it. In the meantime we got thinking... What could have caused the drive shaft splines to strip out? I want to make sure this doesn't happen again. I assume this just doesn't happen with age.

Any thoughts?

 

[BlueFishCrisis]

It does not happen with age. Someone likely removed the engine at some point for a rebuild and failed to properly align it with the jet pump. Sounds like you will need a new coupler, drive shaft, and an alignment tool. I believe I have all the parts you need, and would be happy to loan out the alignment tool. PM me if interested.....

 

[OhSnap]

I wondered if it had something to do with the engine mounts. Any chance the mounts failed?

 

[BlueFishCrisis]

You would be able to move the motor a bit if they failed. It's more likely that someone pulled it to work on it and didn't bother properly aligning the motor. I just had someone else with the same exact scenario. Motor was WAY out of alignment.

 

[OhSnap]

Thanks! That makes sense. I looked at the other parts like the jet prop and housing but didn't see anything that looked out of place or like it had a rock stuck in it or anything so I was a bit concerned this would happen again if I didn't fix what caused it.

I PM'd you about the shaft, coupler and tool also... let me know.