Question about water leaking into Superjet

[yamahahaha]

I've had my superjet for a long time now and it's always leaked in water. I have never been able to figure out where the leak is so I've always just ran the bilge pump while riding. Now it's time to sell so I need to figure this out. I think I have an idea, attached is a picture of a hole in the drive shaft where it connects to the crank (not sure if that is an accurate description so please see pic). I'm wondering if there is supposed to be something over this hole and if this is where water is getting in when I'm riding. If so I would appreciate any input on how to fix this or what part I need.

Thanks! Dylan

 

[CHRISRACERX]

There’s usually a plug on there. Water could come in that way. Can you place the hull in the water without the engine and see?

 

[yamahahaha]

There’s usually a plug on there. Water could come in that way. Can you place the hull in the water without the engine and see?

I could try, but the engine is in right now so I was thinking if I could just disconnect the exhaust and remove the gas tank I could move the engine forward a couple inches just to plug that hole without taking the engine out and hopefully solve the problem. I'm just not sure how to plug it

 

[Big Kahuna]

fill engine bay up with water. Look for the leak that way.

 

[SuperHumanJetski]

I had a leak on my first superjet and I could never figure out where it was coming from until I rode it without the hood on. Turns out the bond rail was leaking. This could be your issue if it's not coming through the midshaft.

 

[yamahahaha]

I had a leak on my first superjet and I could never figure out where it was coming from until I rode it without the hood on. Turns out the bond rail was leaking. This could be your issue if it's not coming through the midshaft.

Maybe but the hull is lined with carbon kevlar so it seems unlikely

 

[yamahahaha]

fill engine bay up with water. Look for the leak that way.

I will try that, do I need to worry about water wrecking anything?

 

[SuperHumanJetski]

just dont let water go over the side of the hull. keep it on plane. you don't want water going into the carbs

 

[yamahahaha]

just dont let water go over the side of the hull. keep it on plane. you don't want water going into the carbs

I filled the hull with water and it was dripping out pretty quickly where the drive shaft goes into the hull, I’m gonna assume that this means that hole in the coupler needs to be plugged. I just don’t know if they make a part for it or if I have to jerry-rig it

 

[Sanoman]

Could be leaking in around the midshaft because the housing itself is not getting a good seal.You may want to pull the midshaft out and run a bead of rtv silicone around the backside of the housing.Then bolt it back on.Recheck in a few hours.For chits and giggles put a blob of silicone in the shaft itself.

 

[yamahahaha]

Could be leaking in around the midshaft because the housing itself is not getting a good seal.You may want to pull the midshaft out and run a bead of rtv silicone around the backside of the housing.Then bolt it back on.Recheck in a few hours.For chits and giggles put a blob of silicone in the shaft itself.

I tried pulling that housing off once, I took off the three bolts but it wouldn't budge, is there something else I'm missing to take it off or do they just get stuck on there pretty good?

 

[Sanoman]

It may already have some sealant holding it.Take a puddy knife and gently see if you can work it in behind the midshaft.You might have to take a hammer and tap the puddy knife to get it to move.Also take a rubber mallet and tap around the housing.lt may have been on there for quite a while.

 

[augustaf]

The op needs to remove the housing- pry it off, besides the 3 cap screws there's just rtv holding it. The 2 small o rings at the other end of the midshaft (on the inside near the end) are likely worn out and no longer sealing against the pump shaft. The water has already washed out all (!) the grease on the splines and is entering through the missing plug opening of the legacy coupler. Later couplers are solid in center, and are available used at a reasonable price.

 

[surfjunkie]

i recently discovered a bad leak on one of my squares. it appears to be coming from the big cracks that run along the joint of the floor and side of inside of tray. at the 90 angle. just giving you ideas of things to rule out....

i was surprised it would make it into the engine area but that seems to be the case based on when it drips

 

[yamahahaha]

The op needs to remove the housing- pry it off, besides the 3 cap screws there's just rtv holding it. The 2 small o rings at the other end of the midshaft (on the inside near the end) are likely worn out and no longer sealing against the pump shaft. The water has already washed out all (!) the grease on the splines and is entering through the missing plug opening of the legacy coupler. Later couplers are solid in center, and are available used at a reasonable price.View attachment 356871

Sorry so what you’re saying is I just need to replace it with a newer coupler? Or are you saying I should replace those o rings and put new grease on the splines? Or both? And if so can you do it by just pulling off the mid shaft and housing?
Sorry I’m pretty clueless about this I’ve never taken it apart before thanks

 

[augustaf]

You need to remove the mid shaft housing assy. to replace those o rings. You'll probably find dry, worn (hopefully still useable) splines. Just the coupler half needs to be replaced- which is not easy.

 

[yamahahaha]

You need to remove the mid shaft housing assy. to replace those o rings. You'll probably find dry, worn (hopefully still useable) splines. Just the coupler half needs to be replaced- which is not easy.

Ok, so coupler half as in put a new coupler half in the old housing which is what is not easy? And if that’s the case would it be easier to just find the entire assembaly with the housing and replace that? Thanks

 

[augustaf]

Yes, that would be easier, but a bit pricey. To just change the jaw coupler you would need to hold the shaft with a pipewrench (gruesome), or a tool. Heating the aluminum coupler slightly would help in removal.

 

[augustaf]

The op's picture shows what appears to be a 62T midshaft housing as used in a rn Superjet. The coupler looks weird, hopefully it's not an early square nose shaft which has a smaller diameter in the threaded area. Most of those were discarded when Yamaha furnished upgrade kits in the early nineties.

 

[yamahahaha]

Sorry I’m not sure what you mean when you say “op”. So sounds like what I need to do is take the entire assembaly with housing off, replace the o rings and coupler with an updated one, grease the splines, then put it back in?

The op's picture shows what appears to be a 62T midshaft housing as used in a rn Superjet. The coupler looks weird, hopefully it's not an early square nose shaft which has a smaller diameter in the threaded area. Most of those were discarded when Yamaha furnished upgrade kits in the early nineties.