Exhaust Hose Explode

[mykd99]

What would cause an exhaust hose to explode?

I was on my 2002 GTX 4-tec the other day at a lake and I sucked up some sea-weed, quickly pulled it out of the intake and it ran fine... for 3 minutes. Then it started bogging down or cavitating again, but not as bad as before. I jumped in the water to clean it out again, but nothing was there. I rode it for about another 30 mins but it was still doing the same thing.

Took it home and looked at the intake system out of the water, nothing was in there. Took it out the following day and it was still doing the same thing. Cavitating like it was being deprived of water, and obviously not reaching full speed, probably about 50mph.

From doing a little research on this forum, I was thinking it was the wear ring.

Took it out again the following day and about 30 mins into it heard a pop and seen smoke coming out of the eng. compartment. Got towed in (about a 15 min. ride) and by the time I got to the launch, the bilge was half full of water. Took it home and realized the exhaust hose was blown (that was the pop I heard). So my question is what would cause this? Sea grass from the lake? And is this my cavitating problem? Could this be causing that issue and not the wear ring?

Thank you in advance.

 

[Chester]

The 4-tec engine has 2 cooling systems. A closed loop system to cool the engine and an open loop system to cool the exhaust and intercooler (if equipped). Some of the seaweed may have plugged the open loop system and restricted the cooling of the exhaust system. If your EGT gets too high, the engine will go into limp mode (lower RPM's). Also, the rubber exhaust hoses will melt and burst. Check for blockage.

Chester

 

[mykd99]

Thank you for the advice.

I have some pictures attached of the damage. It seems that the exhaust host that connect the RH muffler to the LH muffler was too close to the exhaust pipe and the double walled hose split, the outer wall was flimsy and the inner wall was blocking most water flow. This seems to have been an evolving problem. I heard a beep about every 20 minutes, but thought this was due to the fact that my LCD guage was not working, guess it must have been the temperature sensor melting. Now I know.

So I ordered two new exhaust hoses, the LH muffler, the exhaust outlet, and the temp. sensor.

So now I guess the question is why did the exhaust hose melt and the walls split? Is the exhaust hose supposed to be that close to the exhaust pipe? It was tied up with zip ties, but it was still touching the pipe.

Well in two weeks when the parts come in I will let you know how I make out.

 

[Chester]

...So now I guess the question is why did the exhaust hose melt and the walls split?...

Like I mentioned, you have a blockage in the open loop cooling system. Clear it or you will have the same problem.

...Is the exhaust hose supposed to be that close to the exhaust pipe?...

Yes, that is normal.

Chester

 

[mykd99]

Thank you Chester.

 

[mykd99]

Finally got all the parts and put them in. I replaced all the exhaust hoses. I was not able to get a muffler, so I had someone weld up my original one. The baffles were broken, so he removed them.

I took it out yesterday, ran it at the dock for about 5 minutes a little above idle and it was very very hot. Tried to give it gas and it was bogging down and took a while to plain out, had to go easy on the throttle. Almost like it was cavitating. Was not reaching full speed, probably around 50-55mph. And it sounded like it was starving for water.

Took it home and ran it on the hose. I can feel cold water running through the exhaust pipe and the exhaust system looks like it is working properly now. However the engine does not sound right. Did not want to run it too long on the hose, but maybe I should have to see if it got really hot like before.

So now I am thinking there might be a clog in the water intake, or there may be a problem with the water pump. Not sure, please let me know if you have any ideas.

 

[nester]

I think you still got some sea weed in the open loop system like he said. "Limp Mode" is there to save the engine if it is running hot like chester said. You will have to take the entire open loop cooling system off and clean her out.

 

[mykd99]

Nester, thank you for your reply. I will definitely check this, as it seems to be my easiest and cheapest solution at the moment.

I am new to this so can you please explain what the "entire open loop system" consists of? Right now I know both mufflers and the 2 exhaust hoses are clear, along with the exhaust pipe and the exhaust outlet pipe. From looking at the parts catalog 'cooling system', I'm guessing I should check the water pump and connecting hoses? Could something (weeds) really get sucked up in those hoses?

Should I also rip apart the manifold, since that is part of the open loop cooling system?

Thank you again!

 

[nester]

Yes I would be happy to explain. Older skis use an entire "open loop" cooling system for the engine/exhaust system. This is were actual lake water is flowing thru the head/exhaust to cool it and then discharged out the back. On most of the newer 4 strokes they utilize a "closed loop" cooling system for the actual engine and retain the open loop system to keep the exhaust cool. A closed loop system is when there is regular antifreeze in the engine with a small radiator just like a normal automobile setup. The radiator is in a path of regular lake water (open loop) system to exchange the heat. Instead of air moving thru the radiator to cool it, the lake water passes thru it and thus exchanges the heat from the fins to the lakewater. Therefor this is a better system since dirty lakewater never goes thru the actual engine at all. However, this system is still prone to contaminates restricting the heat exchanger (aka radiator) just like dirt would block up an auto radiator. In your case aqua vegetation sounds like the cluprult. As far as taking the system apart and cleaning it, I'm sure you will be able to download a service manual for free and they will explain how to take the entire cooling system apart.

 

[mykd99]

Thank you for the explanation Nester. I will let you know how I make out.