1999 GSX Limited cooling question

[ugafan83]

1999 GTX Limited cooling question

Hey Guys I am new to jet skis but not to boats. Been working on them for a while. I picked up this jet ski and I'm having a problem with a hose on the cooling I believe. When you replace the hose it runs fine for a couple minutes then goes into limp mode. Replace the hose and runs fine till it melts again. Not sure what I need to do. I have some pictures but will try and get some betters one. Thanks Again Guys!

 

[mikidymac]

First please clean that engine up, LOL.
There is a blockage in your cooling system and the pipe is getting so hot it is melting that hose and the engine is getting hot enough to trip the high temp sensor. You will need to pull off all the hoses and blow air through them to fine the clog.

 

[ugafan83]

Haha I just bought it from a friend that had it sitting around so it is in the process of getting cleaned..thanks for the help..do I just pull those smaller hoses off the exhaust and blow air through them toward the transom of the jet ski?

 

[SabrToothSqrl]

Looks like that pipe has been disassembled at some point in it's life.

It also looks like a 99GSX LTD 951 carb, however that ski does NOT have a "limp mode".

the smaller hoses are cooling system indicator lines, which expel water to let you know water is passing through the cooling system. From the hole in this one, it looks like more of an issue than a clogged line.

I believe the hose you have a hole in comes off the water RAVE setup. It varies the amount shot into the exhaust to allow HP gains across the RPM range.

trace this hose back, it should connect at the rear of the ski, on top of the muffler.

if you replace it, make sure to use hose that won't become brittle over time. the oem stuff is the best. I've seen guys use random hose from wherever hardware, and within 1 season it becomes hard/brittle/stiff, etc and leaks.

I do however believe you have more issues than just this hose. If it were my ski, I'd consider pulling the pipe off and checking all the cooling passages.

overheating a 2 stroke engine will result in a significant cost in time and $.

the temp sensors on these are also... i'm going to say not the best... not bad, but not perfect. so you want to make sure you're good to.

salt water, sand, beaches, etc. can all wreck the cooling system.

you don't want to be 4 miles off shore with a bad engine... it's not fun.

 

[ugafan83]

The line that is melted goes to the back of the jet ski..the other hose coming out goes to a piece on top of the muffler..is it possible they are swapped

 

[mikidymac]

Are you sure it is a 99' GSX Limited? The hull should be red not white.

 

[ugafan83]

My apologies it is a gtx limited

 

[mikidymac]

Here is your cooling system diagram to follow.

 

[Sportster-2001-951C-Stock]

Yep, make sure the cooling system isn't plugged with sand and junk! They definitely will overheat that way.

An overheating 2-stroke will tend to lose power, hopefully no damage was done. I would check the compression before continuing to run it, it might be hurt.

That melted water line is the exhaust water injection, water is injected into the exhaust gasses there. This cools the exhaust gasses and adjusts the sonic length of the tuned pipe. At low speeds, more water is injected to shorten the pipe by taking up space and at high speeds less water is injected to make the pipe sonically longer to help scavenge exhaust from the cylinders. Still, a small amount of water is necessary to keep the exhaust expansion pipe cool.

Maybe the other cooling jacket in the first section is plugged. or not getting water.

It's not uncommon to find the cylinder waer jacket is half full of sand, disconnect the drain at the bottom of the cylinder jacket and make sure it runs clear, flush everything out.

Probably your waterbox valve is plugged too, it's the one on top of the "muffler" fart can.

I'd be checking everything.

 

[ugafan83]

ok so according to the diagram the melted hose looks like it is the injector hose( I hope that the right term). So if it is on the diagram it is suppose to be going to the waterbox valve(the thing on top the muffler). Currently though it is going to the very back of the jet ski. The other hose that is in the diagram on top of the manifold thing is currently going to the waterbox. So my question is are these two hose backwards and need to be swapped? Could this cause the melting hose?

Thanks for all your help so far!

 

[SabrToothSqrl]

it could do a lot of things.

 

[mikidymac]

The diagram is correct and if you look at the plastic valve on the waterbox it has arrows to show you the flow into and out of it.

I would still check all of your other hoses and make sure you are getting air into and out of them. Like Sportster said the one that drains the cylinders is very common to plug from sand, rocks and shells. I think the hose was melting because the pipe got hot but that might be the symptom and not the problem. It sounds like your pipe is getting hot from not enough cooling water and that hose is more for performance tuning than outright cooling. The cooling for the pipe comes from the engine through the manifold and into the pipe waterjacket then outlets the other pipe fitting.

 

[soccerdad]

If it is currently plumbed to outside the ski, then you likely have exhaust gasses going out it. That is why it is melting. That is my guess anyway.

 

[Seadoodoc]

Uga has correct diagnosis. Starving pipe for water. Take those two elbos at top of pipe and join them.. it will run. That melted hose wont cause engine to overheat tho. I had a casting chunk stuck in fitting at big line bottom of head pipe.

 

[ugafan83]

Thanks for the help guys!

 

[Mickirig1]

I Had the inlet line get blocked with a wad of plastic. It melted that line and set off the over heat alarm. When it over heated. The top of the head will have in and out arrows for the hoses.