Hot SLTX

[reddave6400]

Has anyone come across/cured a 97 SLTX 1050 that seems to overheat?
I have done a search but can't seem to find a post where the ski has the same problem.

So far I have tried: removing the thermostat and plunger, I have performed a cooling rail mod with front mounted pisser, checked the screen/o-ring on the jet unit and all hoses, fitted a new exhaust mounted temp sensor, rotated the heads 180' so the ex stamp faces the exhaust port (engine reconditioner didn't know) and rebuilt the engine (twice).

The problem happens when I go for a high speed run or load the ski through long sweeping turns, it goes into "HOT" mode and limits rpm etc.
Last time out I felt the water comming out of the pisser after a run and it didn't feel particularly hot at all. The ski has done this with all engines and both original and new sensors.


Some of my thoughts are:

• blockage in the water feed to the pipe/expansion chamber
• electrical fault of some type?
• lean jetting? (plugs and piston wash look good)
• retarded timing? (ski performs really well)
• crank index (has had the crank re-built twice)

any other ideas or help would be really appreciated.

Cheers, Dave.

[Keddano]

Have you took a look in the elect. box yet? maybe open it up and make sure all connections are clean and tight.

[FLjoyrider]

Next time check your exhaust pipe temp.. I'm not sure on yours but I know the seadoos have an exhaust temp sensor and sometimes the sprayers get clogged (or mixed up) for the wet exhaust then it will overheat your pipe!

[casey67]

I think you should check the actual temp,so you could start looking at actual overheat (mechanical/ water flow) or a false warning ( electrical)

The temp sensor closes (grounds ) at 160 degree F / 71 C

[K447]

Check the exhaust water injection screen and orifice for clogs. That is the smaller water hose on the exhaust pipe.

Pisser? Is the cooling system modified from stock?

Post some photos of the cooling system, it might not be correctly configured.

Trace the Tan wire all the way from the Temp sensor back to the electrical box. Make sure the wire is not frayed or pressed against the engine anywhere.

A replacement Temp sensor is not expensive. It might be worthwhile to order a replacement anyway.

Make sure there is no corrosion or signs of moisture inside the electrical box. Check behind the terminal board too.

Are the thermostat and by-pass plunger in place inside the thermostat housing? Any signs of wear or clogging in there?

When the engine cooling is working properly, you should be able to put your hand on any part of the engine or exhaust without burning yourself. If you can hold your hand on it for a few seconds, it should feel 'very warm', but not painful. About 140F.

If your engine or exhaust is getting hotter than that, then it is overheating.

Right after you get the HOT warning lift the seat (or go riding without it, just be careful out there). If you drip some water drops on the engine or exhaust and they sizzle, that is way too hot.

Check the water inlet screen inside the jet pump exit nozzle. The mesh screen is hard to see inside on the right side.

If you want to thoroughly check the water feed from the jet pump, remove the jet pump, and check the entire cooling water flow path for clogs or restrictions.

[reddave6400]

Thanks for the replies and suggestions.

I have modified the cooling system as per this (#9)

http://www.greenhulk.net/show...ht=cooling+mod

The temp sensor is in good shape (only done 6hrs) and behaved the same as the one I replaced. The sensor was really expensive to buy in Australia,and was a pita to fit with the exhaust manifold and expansion chamber still on the engine.

The thermostat and plunger are currently removed and there are no blockages in the housing. I recently replaced the through bearing so I checked the screen and o-ring on the jet unit and they were all good.

Is there a screen in the 1050's pipe where the 5/16 hoses connect? mine looks to be part of the pipe and not removable.

Casey's idea of checking water temp sounds good, that way I could establish if the engine or exhaust is overheating. Can anyone recommend a good guage? I would have to buy it on line.

Hopefully I haven't missed to much of what was suggested, and I will follow up with some pictures of the whole engine/cooling system.

Cheers, Dave.

[K447]

...The thermostat and plunger are currently removed and there are no blockages in the housing.

I recently replaced the through bearing so I checked the screen and o-ring on the jet unit and they were all good.

Is there a screen in the 1050's pipe where the 5/16 hoses connect? mine looks to be part of the pipe and not removable.

Casey's idea of checking water temp sounds good, that way I could establish if the engine or exhaust is overheating. Can anyone recommend a good gauge?...

Did you also check the plastic water tube that goes forward from the jet pump nozzle into the hull?

Check for any kinks or internally collapsed sections in the water hoses.

Item 1 5020668 FITTING,WATER INLET
Item 8 7052128 FITTING,SCREEN,EXH.
Item 11 5020747 FITTING,INJECTOR,EXH .

Water and engine temps you can check by hand. If it burns you, it is too hot. You can check the water box temp as a proxy for exhaust exit temp.

Edit: Note that the exhaust water injection is NOT supplied by the small hose from the tee on the main water supply hose (items 6 & 19 in second diagram).

The exhaust water injection is tapped off a separate nipple (item 8 ) on the exhaust pipe, and feeds the injection orifice (item 11) on the same exhaust pipe. The small hose (item 10) runs from one connection on the manifold to another.

[casey67]

If your sence of touch is good,try that.

Otherwise,a no-contact,infa-red type temp reader would work best,could also check each cylinder,pipe and heads. I saw a cheap one at "harbour freight" ,but don't know how accurate it is.

[reddave6400]

Ok I have had a look at the ski, from what I can see the temp sensor is in the exhaust manifold which is fully jacketed. There is a 5/16 hose which feeds from a plastic tee piece in the main feed from the jet unit, so if this is blocked could it cause an overheat? I do note that the manifold gets full water flow and feeds water into the cylinders which cools the whole engine
I will check it out tomorrow and possibly take it to the beach for a run.

[casey67]

Ok I have had a look at the ski, from what I can see the temp sensor is in the exhaust manifold which is fully jacketed. Yes,the manifold is fully jacketed. Also the upper half of the pipe is also jacketed and cooled by the water from the large hose ( 3/4" ?)
From the pipe,the water then enters the manifold and the engine.
All of those parts should be cool enough to touch.
There is a 5/16 hose which feeds from a plastic tee piece in the main feed from the jet unit, so if this is blocked could it cause an overheat? Yes. All the hoses and passages need to flow freely.

The 5/16 hose from the front of the pipe ( has a screen attached to the fitting at top of pipe) injects water into the exhaust stream ,cools the exhaust gasses and keeps the hoses leading to/from water box,from melting.

I do note that the manifold gets full water flow and feeds water into the cylinders which cools the whole engine Also water from pipe cools the engine.

I will check it out tomorrow and possibly take it to the beach for a run.

Good luck, let us know what you find.

[johnsonmtz]

Dave,
If you can't find any obstructions then is it possible your engine has some salt buildup in the cooling passages You mentioned going to the beach, so does that mean this is a salt water ski?

If all else fails, you may want to try flushing the engine with a salt removing product like Salt Away: http://www.saltawayproducts.com/Outb...ushingPage.htm

Rather than use the back flush port on the cooling rail, I would suggest you fit the water intake tube with a hose fitting. Then hook up the Salt Away flushing system to that. If you pull the pump and drive shaft off the ski, you'll then be able to run the engine as long as you want on the hose without fear of damaging anything. This will let you run the engine up to normal operating temp while flushing and clean out any deposits that may be in there.

I have also heard of people finding a bunch of sand in the bottom of the case, so it's possible you might have sand built up in there too.

KJ

[K447]

...is it possible your engine has some salt buildup in the cooling passages?

...also heard of people finding a bunch of sand in the bottom of the case, so it's possible you might have sand built up in there too...

If you cannot find a blockage in the hoses and fittings, you may need to pull the exhaust manifold and/or a cylinder head off to check for sand build-up inside the water jackets.

See my updated post 7;

Note that the exhaust water injection is NOT supplied by the small hose from the tee on the main water supply hose (items 6 & 19 in second diagram).

The exhaust water injection is tapped off a separate nipple (item 8 ) on the exhaust pipe, and feeds the injection orifice (item 11) on the same exhaust pipe. The small hose (item 10) runs from one connection on the manifold to another.

[reddave6400]

Thanks for all the help and advise so far, I am inclined to think it's not a build up of sand as the engine has only done about 11hrs from a full rebuild where it was chemically cleaned, I did remove the heads at 10hrs to check piston wash and the domes looked clean (water side).
The ski can run all day @ 3/4 rpm and brief wot blasts, and even when it does overheat it will recover at idle in about 10 seconds or so. The ski will overheat quicker with the thermostat and plunger fitted as these maintain the correct higher running temp.

Does the temp sensor get it's signal from the exhaust temp, or water temp? (I'm thinking exhaust and primarily pto cyl) The answer to that will establish if its a combustion/sensor/electrical/jetting problem or if it's water/flow/blockage related I think/hope.
The sensing system seems to work fine just it happens at too low a temp?

I have decided to take it for a run today and see if I can eliminate a few things, will let you know how it goes.

a little background on me, I did work in automotive and light industrial cooling systems for 22yrs.... so this is really frustrating me

[K447]

...The ski can run all day @ 3/4 rpm and brief wot blasts, and even when it does overheat it will recover at idle in about 10 seconds or so.

The ski will overheat quicker with the thermostat and plunger fitted as these maintain the correct higher running temp.

Does the temp sensor get it's signal from the exhaust temp, or water temp? (I'm thinking exhaust and primarily pto cyl) ...The sensing system seems to work fine just it happens at too low a temp?...

The sensor senses water jacket temperature. It sounds like it is doing its job correctly, and you have a genuine overheat condition.

On your engine, the sensor is mounted to the exhaust manifold water jacket.

It really does sound like you have restricted water flow, either throughout the cooling system.

Are you sure the engine is correctly built, with the cylinder head gaskets correctly installed, and no excess sealant clogging the exhaust manifold water passages?

Have you removed and checked the mesh screen and exhaust water injection orifice openings?

[reddave6400]

The head gaskets should be fine, on these engines they are just 2 o-rings and the cooling pasages are cast into the heads themselves. I haven't checked the screen yet, but even if it was completly blocked it wouldn't cause the engine to overheat (through the sensor) as the engine and manifold still get full water flow through the main cooling circuit, the pipe and waterbox would get extremely hot, this I have seen on a buddy's SLT780 with blocked screen, it burned up the rubber hose and blistered paint off the waterbox.
If you have a look at where the sensor fits (my previous pic) it goes into a solid based recess and does not physically touch water, that is why I thought it may sense exhaust temp.

Unfortunately a flat battery stoped me from getting out today so it may be a while before I get a chance to hit the water. I am going to tape a digital thermometer to the hull directly into the stream of water exiting the pisser so I can see what temp it runs normally and what it gets to in overheat. This should give me a better idea of what is going on.

Thanks for the Saltaway info it looks like a great product!