2009 RXT IS melting exhaust

[jhjesse]

Ventured into the 4 stroke world with the purchase of a 09RXT IS. Got for it $5000. Books for around $7400. The gel coat is a little faded and it needs a new seat cover, but overall it is in good shape with only 70hrs. I was thinking I could carry it over the winter and sell in the spring for a small profit.
The dealer I purchased it from took the ski in on trade, did a full service on it, as well as, replacing the IBR.

So I took the ski to the lake to try it out. Cruised around for a while getting familiar with it. After about 3hrs decided to go back to the ramp load up and go home. About a mile from the ramp I hammered the throttle for about a minute. When I backed out of the throttle the overheat light came on as the ski went to limp mode. I shut it off as smoke started coming out the vents all the while I am thinking this is not good. Stood up to lift the seat and the ski pitched over and I fell off. This damn thing is sinking!! Got it to the shore and the engine compartment was full of water up to the top of the engine. Finally made it to the trailer drained the water and took the ski home and spent Labor Day weekend drying it out. Changed the oil 5 times,as well as, everything else.

I don't know anything about 4 strokes and need some advice on what went wrong. I guessing that the cast aluminum head pipe shattered and the hot pieces of aluminum shot through exhaust hose into plastic resonator and melted the connection allowing water in. Not sure?? The water box inlet was also bent where someone over tightened the clamps. Also not sure if this had anything to do with it as well. I have ordered all the parts and can replace them with little or no problems, but more importantly is why did this happen? Any help would be greatly appreciated.

 

[Eclipse1701d]

It is possible that the holes in the j-pipe were partially clogged, not supplying enough water to cool the exhaust when you hammered it. The result of the heat was enough to start the melting process, which resulted in the rest of the damage.

 

[jhjesse]

Thanks for the response. I didn't think to remove the fittings from the pipe and look in the channels for blockage, but it makes sense. I have a new one ordered and so it will be replaced anyway.
Where does the water come from...the jet pump? Do you think the inlet from the pump (I'm assuming) could've been blocked with trash preventing water flow.

I am out of town for a few days. When I get back I will check both the pump and the j pipe fittings.

 

[Eclipse1701d]

It could've already been clogged, partially. There may have been enough flow to keep it cool until you went WOT at the end. However, there should've been a long beep and an error code on your screen BEFORE it happened. There may have been a malfunction with the exhaust temp sensor, and that may be why there was no warning. I am not an expert, but my understanding is that some of the water coming in is diverted through the large rubber hose (on my 155's, anyway) under the exhaust manifold. Then it flows through the three hoses going into the j-pipe. There are veins wrapped around the casing the cools the pipe and shoots out those three little holes to cool the exhaust. While you have the pipe out, I would look into the manifold for any corrosion and check those hoses for any blockage...

 

[jhjesse]

The exhaust temp sensor melted and fell out of the waterbox. That could be why there was no warning.

 

[Sportster-2001-951C-Stock]

I guess if your exhaust water temp sensor melted and fell out and otherwise components melted, that could explain how the bilge filled with water? Any of the plastic and rubber exhaust parts will melt/burn if water flow is disrupted, for whatever reason. Could even be a hose popped off somewhere. Interesting though, the engine continued to run despite the bilge no doubt was filled with exhaust.

I haven't heard anyone mention their exhaust manifold shattered, that's a pretty extreme kind of failure.

A bilge pump in the bilge with hull outlet mounted in an obvious place (by your foot maybe?) could provide a warning the bilge has water inside.

Good luck man, I'm sure you'll get 'er going.

 

[jhjesse]

Update:

Back home after being out of town for a couple weeks and find my parts waiting for me to install them.
Before starting back together with everything, I did some investigating. I checked the inlet water fitting on the exhaust manifold and found no blockage. Moved on to the other elbow fittings on the manifold with the same result. Blew air through the exhaust manifold water channel and found it to be clear as well. I also checked the jet pump inlet fitting and found it to be partially clogged with debris, but not bad. Then as I followed the inlet hose through the hull and into the IBR housing I find the hose almost off the nipple and the clamp just hanging on the hose. Dealer never tightened it after replacing the IBR just before selling it to me. This is the main source of water to cool the exhaust. No water…no cooling! Also makes a spigot for filling a jet ski with water.
Everything is back together now and I have run it on the hose a couple times checking for leaks. I am going to lake test tomorrow. Moral of the story is never trust a Dealers work, always check it yourself.

 

[Sportster-2001-951C-Stock]

No warning buzzer either, it seems, as well as no bilge pump water circulator peeing out the side?

 

[jhjesse]

No way that I have found to warn of failure before it happens. The exhaust temp warning didn't happen until it was to late.
If it runs good I think I will install a bilge pump.

 

[Sportster-2001-951C-Stock]

No way that I have found to warn of failure before it happens. The exhaust temp warning didn't happen until it was to late.

Well that's reassuring. FWIW, some high-end mercruisers have water pressure transducers that squeal when the impeller housing (cheapo aluminum housing, LOL) is worn out.

 

[jhjesse]

Rode for three hours today varying speed, but never went wot until back close to the ramp. Opened her up to wot and read 72 on the speedo for about 30 seconds with zero problems. So I am calling it a success. Now on to the gel coat restoration.