- Location
- Cairns Australia
The access hole I cut to get the foam out.
SJ Leaking water between firewall and hull
- Thread starter Allistah
- Start date
The access hole I cut to get the foam out.
Allistah
Slacker
- Location
- Bay Area, CA
I have my ski on a work stand right now without the gas tank in. I lifted the back end up and down really fast and it wasn't very heavy and I didn't hear any sloshing. Maybe I'm getting lucky. The hole where the exhaust goes through is sealed so any water I'm having wasn't coming from that.
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- Location
- Cairns Australia
The waterline was fairly easy to remove. Pull the pump out, disconnect your rubber water lines and give it a tap with a rubber mallet to loosen it then pull it out the back. Mine was just held in place with a bit of silicon type sealant at the ends and the foam is probably holding onto it inside as well but once it budged it was easy to pull out. The ski was a surf/saltwater ski before I bought it. And it's a 97 model so it's seen a lot of saltwater over a 17 year period.
- Location
- Cairns Australia
There are 2 holes through the engine bay rear firewall about an inch in diameter that
had some sealing tape over them, when I peeled it off and jammed my finger through into the foam I could tell it was wet. I couldn't hear any sloshing but once I dug out the foam the bottom had a horrible foam crumb soup left in there. It was wet right through to the very tail.
had some sealing tape over them, when I peeled it off and jammed my finger through into the foam I could tell it was wet. I couldn't hear any sloshing but once I dug out the foam the bottom had a horrible foam crumb soup left in there. It was wet right through to the very tail.
- Location
- sarcastomento
Your midshaft is probably not sealed to the firewall well so that the water comes in from behind from the water pressure of the pump, where the driveshaft enters to the midshaft in the pump tunnel.
- Location
- Cairns Australia
That area is before the inlet to the pump so there shouldn't be any pressure there. If anything your pump would be sucking air out of your engine bay through the mid shaft assembly and causing cavitation if it isn't sealed up properly. Of course it might still let water in when the ski is sitting in the water.
- Location
- sarcastomento
He needs to run the ski on the tralor in the water with the hood off to look for the issue. Pull coupler cover off and check everything. Maybe it's just a bad hood seal. A surf strap will help with that.
Allistah
Slacker
- Location
- Bay Area, CA
I took the gas tank out, water box, pipe, and pump. There was a tiny leak in the water line going to the engine so I replaced that. Was another leak in the line coming from the pump to the line through the hull. Replaced that. Found that the exhaust hose coming out of the water box was not tight so I tightened that. Also found some black exhaust marks on the side of the engine compartment next to the pipe coupler so thst must have been loose and leaking a bit. I cleaned that up and made sure everything was tight. Sealed the two middle holes that don't get ride plate bolts anymore. Once I get everything back together I'm going to do the trailer test and really watch it close for water coming in.
I do have a chip in the sealing edge of the hood. It's about the size of half of a silver dollar and its on the front between the handle pole bracket and the side of the hull. I'm going to have a friend fix that up for me.
I do have a chip in the sealing edge of the hood. It's about the size of half of a silver dollar and its on the front between the handle pole bracket and the side of the hull. I'm going to have a friend fix that up for me.
- Location
- Cairns Australia
I didn't think about the decel pressure caused by a scoop grate, good point that. A run on the trailer will reveal the culprit. Sounds like you've found quite a few other leaks in this process which is a good thing I guess.
Last edited:
Allistah
Slacker
- Location
- Bay Area, CA
Yeah thanks for all the tips everyone. Really appreciate it. Might be a while before I can get it in the water.. Maybe a couple weeks. When I do I'll be sure to reply back to this thread with an update.
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- Location
- Pasadena, MD
Did you have any luck finding your leak?
Normally with age, the yamaha skis start to split and leak around the bond line. I had a 99 round nose that would sink if it sat in the water for an hour. It leaked at the rear of the hull and came through the firewall just as you described.
You can usually look at the bond line from underneath and tell if it is split.
Normally with age, the yamaha skis start to split and leak around the bond line. I had a 99 round nose that would sink if it sat in the water for an hour. It leaked at the rear of the hull and came through the firewall just as you described.
You can usually look at the bond line from underneath and tell if it is split.