2003 Sportster 4tec overheating exhaust with continuous alarm

[15sportsterseadoo4tec]

15ft 2003 Sportster 4tec 155hp

Two separate issues dont know if they are related.

First: Overheating after running at 3000-3500 rpm for 4-5 minutes while in water. very hot exhaust.

Where should I start if i would like to eliminate blockage and narrow down the cause.

Second: I ran the boat on flush, it idles fine, water temp coming from exhaust normal (obviously because the flush is forcing water through the system) BUT a strange event occurred. The sound changed and went way up, almost as if something had slip or lost it's resistance and was free to spin without any opposing force. The kill was plulled, problem inspected and boat restarted fine with normal idle sound. This had happened a few times last season while under load. The best example I can site is when in water, under load, doing a hole shot. Upon attempt to accelerate from idle to 3/4 full the boats rpms would rise but the boat's speed would not. Upon backing down back to idle and accelerating at a normal to reduce rate a few times the boat's rpms and speed climbed accordingly. This issue I had under load in water appears to be the one i experienced during flush.

The boat is maintained, winterized and has had a new throttle cable installed last season, new impeller and wear ring two seasons ago, new starter, new oil, filter, gaskets, new plugs, good gasoline. It is winterized every year and never run for more then needed to flush the system or inspect an issue.

In sum, the boat exhaust is over heating causing an alarm AND the boat to slip out of gear for lack of a better way to explain the accelerating issue.

 

[Dennis]

The jet pump supplies the cooling water for the exhaust. If the impeller stops turning then the exhaust will overheat. Sounds like you might have stripped splines where the driveshaft goes into the impeller. You'll have to pull the jet pump in order to know.

 

[15sportsterseadoo4tec]

Thank you Dennis for your time and response. If the Splines were stripped would the problem come and go or would it be a constant and irreversible defect noticed every time the engine is started and in gear?

I do agree that if the splines are stripped, the impeller would not turn thus the engine would be starved of water needed to cool the exhaust and thus over heating the engine but the engine runs smoothly for periods of time and randomly whether accelerating or not will decide to go screwy. To be clear the example I stated regarding a hole shot does not exclude the fact that this problem happens at just above idle when cruising as well.

Again your help is great and I look forward to any thoughts , maybe it's best I approach each problem as separate issues. Part of the problem is describing a noise or what is taking place, maybe i'll take a video and post a link to it.

 

[Michael211_2000]

What Dennis said... sounds like your impeller is "slipping" which could only happen if the splines are stripped out. If not the shaft splines then could be a problem in the PTO gears inside the rear of the engine (but sure hope not!). Either way symptoms point to the fact that the impeller isn't turning full time like it should be (stays cool when running on flush port with water hose pressure, overheats when running IN water and engine appears to loose all load at times as I'm reading it).

However do go post in the SeaDoo Boats forum, other Sportster owners might have better ideas for you to check.

- Michael

 

[devonte007]

I agree with everyone else that there seems to be a problem with your propulsion system. I don't like the idea of it being a problem with the drive shaft or impeller since I have never heard of that happening. I would rather point to simple cavitation issues. I know you had the wear ring and impeller replaced a couple years ago but something could have been damaged in during that time. It could also be that the drive shaft carbon seal and/or bellows are finally ready to be replaced.

When the propulsion system is cavitating, you are essentially boiling the water down there and not much thrust is created which also starves the exhaust cooling system of proper flow. I would start by taking the whole jet pump off and seeing what you find. Take a look at the top of the jet pump and make sure all the little holes are free and clear and that the two tubes that deliver water up to exhaust cooling (on top of the jet pump) are sealed nicely. If wear ring and impeller look good, proceed to the carbon seal and bellows next. If you have never replaced the carbon seal then it is probably about time.

Good luck and let us know what you find.

 

[Dennis]

A video would be very helpful. Stripped impeller splines are not that uncommon here in Florida where most vessels are run in salt water. Another cause of stripped splines and/or cavitation are broken engine mounts. :cheers:

 

[ski-d00]

devonte's got it. pretty common on the 4tec boats to cavitate under load and slip. the pump system has to be perfect to work well, any small problem will cause cavitation and I've seen brand new boats from the factory cavitate. check your pump area, could be as simple as a small stick or rock stuck in there.

in the fall, I hear this problem all the time. leaves get stuck in the intake grate, causes cavitation and overheats the exhaust.

if a spline stripped on an impellor/shaft, it's toast and won't go anywhere but is very uncommon here in Ohio.