SJ4 taking on water

[segmentlime]

My SJ4 is taking on water. If i ride it for about 20 mins it can have as much as 3 inches depth in engine compartment, so we are talking about many liters in just that time.

I secured it to a jet ski lift and let it sit for half an hour or so, and there was barely any water at the low point near where the siphon pump pickup is. Then i ran it for about 5 mins or so and it did seem like a little bit of water was accumulating but not much, but even though it was lashed to the lift i was not able to run at higher throttle the same as when riding hard - the lift and ski was just moving all around.

It seems the water is coming in when riding and the more aggressive the riding the faster it come in. In off season changed to a solas impeller. There was no problems at the end of last season but this has been a problem since the impeller change, and so it seems too much of a coincidence that this is not somehow related.

The siphon hose is connected to the reduction nozzle but if any is siphoning out I guess it just cannot keep up.

It does not seem like it could be anything to do with the pump, but i am wondering if perhaps it is something to do with the mid-shaft; do you think i could have screwed something up with this changing the impeller? One time when the pump was off and the shaft was just sticking out through the transom, i did run the engine for about 15 seconds then thought better of this and shut it off. Is it ok to do so, or could a bearing or seal have been damaged by this?

Any thoughts on what it could be and what I should do?

I do not have any of the tools for pulling any bearings or anything so i am wondering about taking it to the dealer where i bought it.

 

[SteveC]

Any chance you hooked up the siphon wrong, such that it’s pumping water in, not sucking it out?

 

[Big Kahuna]

You ran the motor with the pump removed???????? This could have made the drive shaft bounce around and possible messed up the seals...... Assuming the Drive shaft stays in place when you remove the pump, unlike the older SJ's

 

[segmentlime]

Any chance you hooked up the siphon wrong, such that it’s pumping water in, not sucking it out?

the siphon hose sticks out the transom and connects to a tube connected to the reduction nozzle. i have the service manual and it is for sure hooked up as it was and as per the manual. the only thing in that regard that is not the same as it was is that the hose connected to the tube on the reduction nozzle was secured with a small zip tie but the hose is on there and not coming off and i cannot imagine the zip tie is really doing anything. i will put one on just to be certain but i really doubt this is the problem.

i may try an experiment with the ski hooked to the lift and just running at idle and add some water and see if the siphon seems to suck it out.

the water only seems to build with riding.

i wondered if maybe a cooling line has split or come loose but i could not see any signs of leakage and the pisser has really good pressure.

i am going to try to look more carefully again.

 

[segmentlime]

You ran the motor with the pump removed???????? This could have made the drive shaft bounce around and possible messed up the seals...... Assuming the Drive shaft stays in place when you remove the pump, unlike the older SJ's

The shaft stays in place when the pump is pulled and just sticks out the back of the transom like other yamaha sit downs. The splines on this shaft join with the splines on the forward (towards the bow) inside of the impeller. When you put the pump back on you line up the splines and slide the whole pump unit onto this shaft and bolt the pump unit to the transom.

You ran the motor with the pump removed????????

Yes, stupidly i realize, but only for 15 seconds or so and the shaft was just spinning and not wobbling all about or anything.

I talked to a guy at the dealer and he said they doubted that a problem with the seals could account for that much water, and that a more likely symptom would be cavitation. I don't seem to have unusual cavitation. This doesn't mean it isn't this though. Like i said, i am suspicious of something like this since it just seems too much of a coincidence to having started after doing the impeller job.

The dealer didn't have anything in the way of suggestions, and of course says the only way they can know for sure is to bring it in.

 

[Big Kahuna]

Cavitation is just air build up around the prob blades. Low Pressure areas......... Not got anything to do with water getting inside hull. I am thinking there is a waterline leaking. Put ski in water, tie off to dock or trailer. Crank ski with hood off and watch, apply throttle to put a load on the cooling system. I would bet that you will see water coming in........ Or, Does the bilge system make a loop up high then return, Has the vent fallen down?????? This could cause the bilge to let water back in....... Need to go look in my hull at this ..

 

[Quinc]

run the ski hooked up to the hose and see if it starts filling up. Could also fill the hull up with water up to the intake and see if water leaks out?

 

[SteveC]

Just ride it with hood off and observe. What could go wrong?!

 

[segmentlime]

Just ride it with hood off and observe. What could go wrong?!

oh, why didn't i think of this?

 

[segmentlime]

Cavitation is just air build up around the prob blades. Low Pressure areas......... Not got anything to do with water getting inside hull. I am thinking there is a waterline leaking. Put ski in water, tie off to dock or trailer. Crank ski with hood off and watch, apply throttle to put a load on the cooling system. I would bet that you will see water coming in........ Or, Does the bilge system make a loop up high then return, Has the vent fallen down?????? This could cause the bilge to let water back in....... Need to go look in my hull at this ..

What i am saying is that the mechanic at the dealer said that when he has seen problems with the mid shaft bearing/seals the skis typically have cavitation as the symptom, more so than leaking. i guess this doesn't really mean anything because water is getting in there somehow.

When the ski sits in water without running, then little or no water is coming in. I have done as you said and watched while with hood off tied to lift and none of the water lines appear to be leaking. Under higher throttle and can see the water accumulating. The water under the mid shaft coupling is disturbed but i cannot tell if this is from the action of the leaking near there or if this is just water accumulating high enough so that the shaft coupling turning is beginning to churn the water.

The siphon hoses seem fine. I could not really tell if the siphon was doing anything. I added a bit of water and watched at idle and the level seemed to stay about the same. So maybe at idle what is coming in is equal to siphon but at more throttle it can't keep up.

 

[segmentlime]

run the ski hooked up to the hose and see if it starts filling up. Could also fill the hull up with water up to the intake and see if water leaks out?

These seem good ideas. I have been running on the hose recently when changing oil and adjusting the TPS to eliminate the initial lag. I did not notice that any water was getting it there at all. I will try again though and confirm.

Then i will do as you suggest and fill it up a good ways and watch to see if it leaks out.

 

[Big Kahuna]

What i am saying is that the mechanic at the dealer said that when he has seen problems with the mid shaft bearing/seals the skis typically have cavitation as the symptom, more so than leaking. i guess this doesn't really mean anything because water is getting in there somehow.

When the ski sits in water without running, then little or no water is coming in. I have done as you said and watched while with hood off tied to lift and none of the water lines appear to be leaking. Under higher throttle and can see the water accumulating. The water under the mid shaft coupling is disturbed but i cannot tell if this is from the action of the leaking near there or if this is just water accumulating high enough so that the shaft coupling turning is beginning to churn the water.

Ok, had to think, yes, if midshaft housing is leaking, the air pulling thru can cause cavitation. Was thinking of cavitation at the prop...

 

[SteveC]

These seem good ideas. I have been running on the hose recently when changing oil and adjusting the TPS to eliminate the initial lag. I did not notice that any water was getting it there at all. I will try again though and confirm.

That’s good diagnostic info. If running on hose and no water gets in, it’s likely not the cooling pathways.

I still suspect siphon. Maybe detach it in engine bay and run the hose overboard, then rev up and see if water comes out.

 

[segmentlime]

That’s good diagnostic info. If running on hose and no water gets in, it’s likely not the cooling pathways.

I still suspect siphon. Maybe detach it in engine bay and run the hose overboard, then rev up and see if water comes out.

Thanks for this idea. It might be easier to just unhook the siphon hose at the reduction nozzle and block off that end. Then run for a bit under exact same conditions as was filling up when connected and see what happens. If it keeps dry then that narrows it down. If it fills then I know reverse siphon is not it

I am going to try this tomorrow and let you know.

 

[Big Kahuna]

I looked at mine. It does have the hose with the valve that goes up under hood seal area like other skis. Check the valve.

 

[segmentlime]

I looked at mine. It does have the hose with the valve that goes up under hood seal area like other skis. Check the valve.

The “valve” is the L shape connector at the high point?

 

[spinyard]

The “valve” is the L shape connector at the high point?

Yes, anti siphon valve, if the hole is plugged it will siphon water in instead of out of the hull

 

[Quinc]

it sounds like you have a split in a cool line. Faster riding = more pressure/water. If you can hook the hose up from the hose coming off the pump to mimic real world that would be best.

 

[segmentlime]

Update: some joy yesterday, with experimentation confirming the problem is the siphon bilge running in reverse!

I unhooked the siphon hose from the reduction nozzle and used a twist on electrical wire connector (marrette) as a bung and secured that in the hose with a bit of Tuck tape. Then I rode around in a very similar fashion and duration as when i was taking on water, and then came back to the dock to check - no water to speak of in the engine compartment and just a tiny dribble when i opened the hull plugs; this compared to maybe 2 to 3 inches of water in the engine compartment when the siphon hose was connected.

Today I hope to look more carefully at the siphon setup. The service manual mentions the hole (noted by @spinyard in their post above) in the L joint (valve?) at the high point of the siphon hose routing. The manual doesn't say anything about a problem of sucking water in, but it does say that if the hole is clogged it should be cleaned, and checking this to make sure it is clear is a part of the suggested regular maintenance.

Like @Big Kahuna indicated, the valve or whatever it is, is under the hood rim at the back right corner of the engine compartment opening, and is held in place with a zip tie. It looks like the only way to check the hole will be to cut the zip tie and move it out to get a better look and access if it needs cleaning.

Any way, thanks all the support and a massive relief to confirm the cause is something that should be a relatively easy fix.

 

[segmentlime]

Update: some joy yesterday, with experimentation confirming the problem is the siphon bilge running in reverse!

I unhooked the siphon hose from the reduction nozzle and used a twist on electrical wire connector (marrette) as a bung and secured that in the hose with a bit of Tuck tape. Then I rode around in a very similar fashion and duration as when i was taking on water, and then came back to the dock to check - no water to speak of in the engine compartment and just a tiny dribble when i opened the hull plugs; this compared to maybe 2 to 3 inches of water in the engine compartment when the siphon hose was connected.

Today I hope to look more carefully at the siphon setup. The service manual mentions the hole (noted by @spinyard in their post above) in the L joint (valve?) at the high point of the siphon hose routing. The manual doesn't say anything about a problem of sucking water in, but it does say that if the hole is clogged it should be cleaned, and checking this to make sure it is clear is a part of the suggested regular maintenance.

Like @Big Kahuna indicated, the valve or whatever it is, is under the hood rim at the back right corner of the engine compartment opening, and is held in place with a zip tie. It looks like the only way to check the hole will be to cut the zip tie and move it out to get a better look and access if it needs cleaning.

Any way, thanks all the support and a massive relief to confirm the cause is something that should be a relatively easy fix.

The other day, I tried to fix this and disconnected the right angle piece at the top of the siphon hoses just under the rim. This piece is not a valve, it is just makes a right angle bend in the flow and has a small hole in one side of it -- i guess this to allow the water to drain back out both directions when a siphon is not in effect. I poked a pin in the hole and was not sure but thought possible it cleared something out - not certain though, but the hole was clear. I reassembled the siphon hose and reconnected at the reduction nozzle. Took it for a spin about 20 mins and when I got back to the lift, the ski was 3 inches full of water again.

I am not sure why but the siphon has got to be running in reverse. The little hole in the right angle connector is clear and the bottom under where the water should be pulled seems to be clear.

Anyway the whole thing seems a weak design in any case. And I am fed up of messing with it. I have disconnected it at the reduction nozzle and bunged the open hose again. No water to speak of is entering the hull when i ride it like this. I figure this will be permanent as I have ordered an electric bilge pump kit with a billet switch that attaches under the Yamaha SS , and will install that as soon as it arrives.