What happens in the superjet when it verheats?

K

Killerpirate

Location
Sliedrecht
Hello,

I am wondering, what happens when the temp sensor of a stock superjet from 2016 gets high/engine gets too hot? Does it activate a rev limiter, or does it short the ignition or something?

I ran mine today very hard and pretty long and suddenly it died. Had trouble starting for a while, started sometimes and accelerated a bit, but would then die again. I thought low fuel, but tank was still full enough. 15 minutes later it ran fine again.
 
M

motox331

Location
Illinois
I had this happen to me on my 2020. While I do not know for certain, I think i pinched my gas tank vent hose under the hood and was creating a vacuum in the fuel tank. Make sure your fuel tank vent hose is free from kinks or pinches.
 
Jhucke

Jhucke

Location
Wisconsin
Killerpirate said:
Hello,

I am wondering, what happens when the temp sensor of a stock superjet from 2016 gets high/engine gets too hot? Does it activate a rev limiter, or does it short the ignition or something?

I ran mine today very hard and pretty long and suddenly it died. Had trouble starting for a while, started sometimes and accelerated a bit, but would then die again. I thought low fuel, but tank was still full enough. 15 minutes later it ran fine again.
Click to expand...

My SO overheated a blaster one time. A cooling line got pinched off and she did not notice that there was no water coming out of the pisser. It started to run funny so she turned it off & this thing was absolutely smoking. So hot that the paint straight up started to peel off the head, but it never seized. I tested compression a couple days later and it was even and fine, ran fine ever since then.

Having said that, I chased a fuel filter issue like an idiot for a long time once. I had just replaced it, figured there was no way my ski would keep dying at full throttle because of that, surely! Well it was one of the last things I checked, and sure enough it was plugged. Check the easy stuff first.
 
bored&stroked

bored&stroked

Urban redneck
Location
AZ
Check valve for gas tank might be an issue as well. If the easy stuff doesn't pan out you can always pull a plug and look at the cylinder walls, or pull the exhaust manifold to see the pistons for signs of seizing.
 
kevbo

kevbo

Location
dfw
The heat sensor will slow the engine to idle if the head gets too hot. It is set really low so I engage it every time I blow the water out after a ride. It is still possible to stick a piston with normal water temperature. Any damage will show up on a compression test. One cylinder will be significantly lower than the other. The only time I had a ski consistently quit a full throttle, it had a clogged fuel filter.
 
wmazz

wmazz

Location
Riverside, CA
Killerpirate said:
I ran mine today very hard and pretty long and suddenly it died. Had trouble starting for a while,
started sometimes and accelerated a bit, but would then die again.
Click to expand...

Has it ever happened before? Because it was hard to re-start I would look at the
fuel system. If it had seized for the first time, most engines will usually restart
quickly. That is one reason why seized engines are seized repeatedly 5 or 10 times.

Have you ever replaced the fuel tank filler cap? If the gas cap gasket is missing,
there might be water in your carbs. When people replace the gas cap, they often
leave gasket in the old cap.

Is your inline fuel filter full. Good filters will be ~1/2 full when they are in good
condition.


Jhucke said:
My SO overheated a blaster one time. A cooling line got pinched off and she did not notice that there was no water coming out of the pisser.
This thing was absolutely smoking. So hot that the paint straight up started to peel off the head, but it never seized.
Click to expand...

When an engine gets that hot you should replace the composite gaskets on the
head and exhaust manifold.

At the very least, you should re-torque the head and exhaust manifold bolts.


Bill M.
 
K

Killerpirate

Location
Sliedrecht
Well if it had overheated, it would have gone into limb mode right? That was not the case, it was just hard to start after dying.

What could be the reason of a seizure? The first thing i did after it died whas trying to turn over the shaft by hand via the water intake. Offcourse i couldnt get it trough its compression but there was small movement, so it wasnt stuck in my opinion.

How could a seizure have happened? I added plenty of oil, pisser was pissing good. hydrolock is unlikely since it ran great after 15 minutes rest. Ill check compression and inline filter. Will also check vent hose
 
Jhucke

Jhucke

Location
Wisconsin
Killerpirate said:
Well if it had overheated, it would have gone into limb mode right? That was not the case, it was just hard to start after dying.

What could be the reason of a seizure? The first thing i did after it died whas trying to turn over the shaft by hand via the water intake. Offcourse i couldnt get it trough its compression but there was small movement, so it wasnt stuck in my opinion.

How could a seizure have happened? I added plenty of oil, pisser was pissing good. hydrolock is unlikely since it ran great after 15 minutes rest. Ill check compression and inline filter. Will also check vent hose
Click to expand...

Seizure here meaning, a 'lean-seizure'. Air to fuel ratio containing an insufficient amount of fuel for too long of time, causing combustion chamber to experience increased temperature enough to cause the oil film to burn off the cylinder walls. Due to the lack of or damage to the protective oil film, friction between the piston and cylinder walls can cause scoring, leading to additional friction and ultimately seizure. Metal transfer can occur if the condition is bad enough which can result in a completely locked up engine until it is ripped down and rebuilt, but this isn't always the case. So just know a seizure doesn't always result in a total long term lock up.

Not saying that your engine seized, but that is what these guys are talking about.
 
bored&stroked

bored&stroked

Urban redneck
Location
AZ
Cold seizure. Pistons warm up quicker then cylinder. Engine locks up until cylinder heats up and expands back to operating tolerances. When I last did my top end I found evidence of seizure even though compression was good.
 
K

Killerpirate

Location
Sliedrecht
So what are the factory settings on the carbs of a stock 2016 superjet? The previous owner messed with the settings i believe, because he had the issue that on the first startup of the day (first minute while running) it would bog down when he applied throttle. This problem still exist btw. Every time i hit the water, the firsy minute i can only apply throttle very very little or else it wil bog down. Sometimes when im on plane and want to accelerate it holds back for a small amount of time .
 
wmazz

wmazz

Location
Riverside, CA
wmazz said:
Because it was hard to re-start I would look at the fuel system.

If it had seized for the first time, most engines will usually restart quickly.
Click to expand...

Because it took a long time to restart, I do not believe the engine seized.

I also don't believe it cold seized.

That said, when you ride and it is cold, normally you need to rejet the
carbs for more fuel. Engines need richer jetting in cold air.

Maybe cold water too?

I don't know what your air and water temps are?

Also, what spark plugs are installed and what premix oil ratio are you
mixing at?


Bill M.
 
Last edited:
J

Jacob hates jet skis

Location
Michigan
Happened to me last year on my 04 sj with temp sensor delete. Whenever I would ride the ski for a few minutes it would go into the “limp mode” because the electronics were a little messed up lol. It shut down one of the cylinders and the ski would only go 15 ish mph, therefore its almost impossible to overheat. P.S. had to put in a new sensor.
 
You must log in or register to reply here.
Top Bottom