overheated

Help! I have a 1994 Kawasaki SS750 jetski. It used to run perfectly. Then I did two things: 1. changed to an aftermarket impeller; and 2. fixed a stripped exhaust thread. Immediately after, the engine began to run piping hot. I've opened it up twice and checked all of the areas that cooling water would flow -- can't find any obstruction. I've put the original impeller back in -- still runs hot. Some water comes out of the cooling overflow on the side of the hull, just as it did before. If I run it with a garden hose attached to the engine, it runs cool. As soon as I run it in the lake, it only takes a few minutes to get really hot. Any ideas on what could be wrong? Are there any exhaust parts that I may have re-installed wrong? I hope someone can help -- my kids keep asking "When are we going to get the Jetski working?"

550subman

I don't know much bout your ski and anyone correct me if im wrong but if it seems to run cool on a hose I would chech the cooling lines from there back to the pump housing. This is where it can get clogged and not suck up fresh water when on the lake. Other than that I don't know. Good luck with it though.

Ponda

Hmmm...so you do have a steady stream of water coming out of your pisser?

Engine cooling is pretty simple. If water is getting to the block - it should stay cool. Seems like you may have a clogged hose.

overheated

Thanks guys. I did disconnect the supply hose and ran water through it. No indication of blockage, and it didn't improve things. Any other possibilities?

550subman

Is your ski running bad when you say it seems hot? Or does the aftermarket exhaust jus have less water running through it? The coffman pipe I have on my ski has no water jacket like the stock pipe does so it makes it seem hot but its not. Look up the normal running temp and get a temp gauge and check.

550subman

Forget all of what I just wrote I missread your post. Stock exhaust. Got it.

Tom1965

I have the same situation, happened on both my Xi and ST. Both engines blew. On the Xi I rebuilt it and it runs cool on the hose but once I put it in the water it starts overheating almost immediately. A steady stream is coming out of the pisser but it's very hot water. Water seems to be flowing through all lines correctly. I didn't think it is a lean carburetor issue as it runs hot even at slow speeds and almost right away. Anybody have an ideas? Could the water box be blocked some how, causing insufficient water flow?

Help please!!!

ggauvin

How hot is "Hot"??. The pisser water does run hot to the touch, but it shouldn't be sputtering with steam. After a run, you should be able to put your hand on the heads, cyclinders and exhaust pipe. It will be hot, and you won't be able to hold your hand there very long... but it should NOT scald you. Drizzle water on it... does it sizzle?
That said, maybe you disturbed something in the exhaust pipe when you fixed the threads. Cooling water flows from the pump, into the lower exhaust manifold, thru the jugs, out the head, into the pipe(just the water jacket shell on the pipe). At that point, some exits the pisser, and some enters the exhaust gas flow itself. If that last part is blocked, the small orfice on the pisser won't let adequate flow get thru the jugs.
On the hose, the pisser water never went thru the jugs... engine heat actually gets reverse flow and exits thru the rear pump so it probably does run a lot cooler.

Tom1965

I fixed the overheating problem. It was the jet pump, too much clearance between the impeller and pump housing. Mine was double the wear limit. I got a used pump and put a new impeller in and she's now running much cooler. Before the water out of the pisser was steaming. I think this might be a common problem with a lot of the older Kawasaki's. First I thought both engines failed due to oil pump failure, but now I'm pretty sure it was due to overheating.

Just a word of advise to others in similar situation, if your engine fails don't assume it was an oil pump failure, check your jet pump clearance, you may be overheating and not even know it.

FireTechFerrell

What is the sensor on the pisser line?? temp?? or just psi?