Black adhesive between transom and jet pump?

[scooper77515]

Why is it there?

Both sides of the mating surface are submerged, so why goop it all up?

Seems like just a little dollop around the tube that goes into the hull for the water line would be sufficient.

This is always a hassle to break free when pulling off the jet pump, and a mess to clean up.

Just wondering before I go out there and goop it all up again...

 

[timmyboy76]

Yo scoop...if read your thread right, think you answered your own ?...

quote..Both sides of the mating surface are submerged, so why goop it all up?

 

[scooper77515]

That is why I am asking...I just don't know why all the ones I have worked on were gooped up nasty-like. I think they were both done that way at the factory.

Unless someone can convince me otherwise, I will try just a thin layer of sealant and then a little more goop round that water inlet tube. If nothing else, it may provide a bit of cushion to soften any vibrations from the driveline.

If you don't hear from me by monday, it means something bad happened and I went down with my boat :ack:

 

[Jared]

Im no expert, but i believe it is gooped up to prevent the pump from leaking. The pump has to pressurize to have forward motion and if the pressure just leaks out between the transom and pump instead of the nozzle, you will never be able to get the pressure needed to gain speed. I hope that makes sense.

 

[meirvin]

Jared is correct an leak causes cavitation which is like spinning your wheels on wet pavement

 

[scooper77515]

Makes sense...I thought of that, but also thought that this is the low-pressure side of the pump and pressure and sealing would be more of an issue on the high-pressure side. The end attached to the hull is like the top open end of a funnel, and shouldn't need to be sealed water tight. That was just my logic of thinking. Of course, the more "pure" the water coming in, the better it will pressurize and provide thrust, so a good seal would only help in the end.

Anyway, I used no black gunk except on just the water inlet hose that goes into the transom. It appears to be working really well.

The wear ring has a pretty sharp lip around it, and there is a foam ring on the inside against the hull. I used a thin layer of black gunk to hold the foam in, and then when you torque down the jet pump, the lip embeds itself into that foam.

Now, it has been almost a week, and I may be remembering this incorrectly, but I think the manual said if it has a lip, just put it on, but if it doesn't, then use adhesive....I am out of town and cannot read the manual to verify it, but I think I remember reading that.

 

[jwick86]

The black adhesive really helps out for cavitation. My GTX was not sealed and when I redid the oil in the pump I sealed it and rode it again and the difference is deffinitally noticable.

 

[scooper77515]

Oh well...gonna have to live with it for a while. Will add it next time I pull it apart.

 

[jwick86]

I really wouldn't live with it. It only take a short time to pull the pump out and re-install it after putting the gasket sealer on. Well worth the time spent. I use stuff called "The Right Stuff" and it seal's very well.

 

[scooper77515]

Only problem is, the boat runs GREAT as is, and is running at 150% of the way it ran before I swapped engine and impeller, so I see absolutely no reason to tear it down and "fix" it.

It now takes off and planes in less than 5 seconds with 4 overweight people in it, so I have no complaints or reasons to tear into it for 2 hours to "fix" it by putting in some black gummy crap.

It usually only has 2 overweight people in it, so as far I can tell it is running much better than stock.

So, if I ever have to swap the wear ring out again, I will goop it up. Otherwise, it runs better now than it did when I bought it, so I will leave it as is...

 

[Jared]

I agree.... why fix something that is not broke? If your're running that well, obviously there is no leak so why not ride til you notice any cavitation, that is if it ever cavitates?