Towing: Which line to "pinch off" when towing?

[Carboncow]

So I'm reviewing posts about pinching off water supply while towing...and I see the mention in the owners manual with the TERRIBLE photo. Seriously, did they hand chisel these images in the book onto stone?

Can someone share a clear and consider image of what line is coming out of the intake to shut off? I even see other posts talking bout alternate lines but I'm looking for the simply one for C180.

I may add a shut off and strainer as show in this photo from another post.
Additionally, what other water intakes are there for calling that allow intrusion into the engine and/or exhaust? Is this the only one?

 

[JPass]

You want to kill the water coming from the pump into the exhaust manifold (log). My shut off valves are coming off the exhaust log (not into it), but either will work. I chose my location for the visibility aspect of it as my chances of forgetting they're closed (and damaging the motor) far outweighs the dangers of having water enter the log and into the cylinders through a pin hole leak in the log.

 

[Carboncow]

You want to kill the water coming from the pump into the exhaust manifold (log). My shut off valves are coming off the exhaust log (not into it), but either will work. I chose my location for the visibility aspect of it as my chances of forgetting they're closed (and damaging the motor) far outweighs the dangers of having water enter the log and into the cylinders through a pin hole leak in the log.

So there is no benefit other then ease of access/visibility...same result?

I was hoping for a photo or two to idiot proof this for me, if not...

1. Is it pretty obviously that only one comes out of the pump area?
2. Is it pretty obviously what the exhaust log is?

I'm pretty good around the engine but at the end of the day I just see 10 different hoses down there running everywhere.

 

[Sportster-2001-951C-Stock]

The goal is to keep the exhaust system from filling with water and back-flooding into the engine. If this happens, the engine can fill with water and hydrolock while being towed, the engine oil will also become contaminated if this happens.

You can pinch either one or the other (your choice) of two hoses, pinching either of these will stop water from entering and filling the exhaust system.

Cooling water from the jet pump pressure tap enters the cast exhaust manifold water jacket through the nipple at the front of the exhaust manifold casting and exits the cast manifold water jacket at the two rear nipples (upper and lower), a once through path.

The water exiting the exhaust manifold casting (upper nipple) flows into the exhaust system pipe where under ordinary conditions it mixes with hot exhaust exiting the cast manifold exhaust outlet for controlling exhaust gas temperatures and both water and exhaust mixture eventually exits through the transom exhaust, carried by the continuous exhaust-gas stream. Pinching this upper nipple hose that delivers water from the exhaust manifold casting to the exhaust pipe will also stop water from flooding the exhaust system.

So either one or even both, may be pinched.

 

[Carboncow]

The goal is to keep the exhaust system from filling with water and back-flooding into the engine. If this happens, the engine can fill with water and hydrolock while being towed, the engine oil will also become contaminated if this happens.

You can pinch either one or the other (your choice) of two hoses, pinching either of these will stop water from entering and filling the exhaust system.

Cooling water from the jet pump pressure tap enters the cast exhaust manifold water jacket through the nipple at the front of the exhaust manifold casting and exits the cast manifold water jacket at the two rear nipples (upper and lower), a once through path.

The water exiting the exhaust manifold casting (upper nipple) flows into the exhaust system pipe where under ordinary conditions it mixes with hot exhaust exiting the cast manifold exhaust outlet for controlling exhaust gas temperatures and both water and exhaust mixture eventually exits through the transom exhaust, carried by the continuous exhaust-gas stream. Pinching this upper nipple hose that delivers water from the exhaust manifold casting to the exhaust pipe will also stop water from flooding the exhaust system.

So either one or even both, may be pinched.

Great info...but I have yet to see an idiot proof photo! I'll have the cover off tomorrow for my sea trail so I'll try to make heads and tails of things based on these excellent explanations and (mostly) excellent drawing!

If i cannot figure it out from that drawing I prob have no business touching an engine...ha!

 

[JPass]

Here's a link with a photo of where I placed mine: http://www.seadooforum.com/showthread.php?82201-Question-about-where-I-mounted-exhaust-cooling-cut-off-valve

I placed mine where they are because I like how visible they are and can easily be checked.

 

[Carboncow]

Here's a link with a photo of where I placed mine: http://www.seadooforum.com/showthread.php?82201-Question-about-where-I-mounted-exhaust-cooling-cut-off-valve

View attachment 35081

Oh man that really seals the deal. Good photos. I have to add...the image in your book is way better then my cave drawing from 2007!

 

[Sportster-2001-951C-Stock]

Your boat is one of the 1st I guess, that actually came with more than an owners manual and parts list. I use the jet ski service manual as there was no service manual covering the earlier boats (same ski engine though, minor differences accordingly).

 

[RowdyRod]

It depends....

I think the pinch off position depends on your engine and what year it was made....

For the 2007 4-tec engines there is really only one spot to add the pinch off, and that's on the water intake line.... unless you want to install multiple taps on each of the lines exiting the exhaust manifold.

 

[Sportster-2001-951C-Stock]

I think the pinch off position depends on your engine and what year it was made....

For the 2007 4-tec engines there is really only one spot to add the pinch off, and that's on the water intake line.... unless you want to install multiple taps on each of the lines exiting the exhaust manifold.

View attachment 35124

Looks like you're right about this Rod, and on the SC unit you posted looks like that pincher needs to be closer to the jet pump.

 

[JPass]

I'd put the valve as close to the transom as possible. That's probably the most visible spot. Is that line 3/4"?

 

[Carboncow]

Yea I'd love to know the inside diameter too. I'd prefer to pick up a ball valve on way home rather then cut, measure then drive to get it! Can anyone confirm?

 

[RowdyRod]

I will check mine now... my motor is currently at the workshop and the hose and exhaust manifold are on my workbench....

Inside Diameter of the intake hose is 19mm, so 3/4 inch fittings will work as well.

 

[pete63]

yeah 3/4 plastic ball valve, no problems

 

[borismartin]

Great Thread and Insight: here's a vid in case helpful to anyone in future

The goal is to keep the exhaust system from filling with water and back-flooding into the engine. If this happens, the engine can fill with water and hydrolock while being towed, the engine oil will also become contaminated if this happens.

You can pinch either one or the other (your choice) of two hoses, pinching either of these will stop water from entering and filling the exhaust system.

Cooling water from the jet pump pressure tap enters the cast exhaust manifold water jacket through the nipple at the front of the exhaust manifold casting and exits the cast manifold water jacket at the two rear nipples (upper and lower), a once through path.

The water exiting the exhaust manifold casting (upper nipple) flows into the exhaust system pipe where under ordinary conditions it mixes with hot exhaust exiting the cast manifold exhaust outlet for controlling exhaust gas temperatures and both water and exhaust mixture eventually exits through the transom exhaust, carried by the continuous exhaust-gas stream. Pinching this upper nipple hose that delivers water from the exhaust manifold casting to the exhaust pipe will also stop water from flooding the exhaust system.

So either one or even both, may be pinched.

This is one of the best, most concise explanations online for which 2 lines you can pinch/valve-off, and safely close of the the exhaust cooling circuit when being towed; THANK YOU! I put together a quick video that looks at a couple schematics and highlights these lines again, really just repeating what you've laid out, but hopefully a little more visual and may help some folks not so familiar with the layout follow along.

https://youtu.be/suo9hYeFzdU

Great thread guys, thanks for the info!

 

[borismartin]

Hey Guys/Gals,

Here is a quick "How To" video on the in-line valve install in case it's helpful for anyone needing to do this.

https://youtu.be/pywXJMXlBmw

Cheers

 

[alindley]

The goal is to keep the exhaust system from filling with water and back-flooding into the engine. If this happens, the engine can fill with water and hydrolock while being towed, the engine oil will also become contaminated if this happens.

You can pinch either one or the other (your choice) of two hoses, pinching either of these will stop water from entering and filling the exhaust system.

Cooling water from the jet pump pressure tap enters the cast exhaust manifold water jacket through the nipple at the front of the exhaust manifold casting and exits the cast manifold water jacket at the two rear nipples (upper and lower), a once through path.

The water exiting the exhaust manifold casting (upper nipple) flows into the exhaust system pipe where under ordinary conditions it mixes with hot exhaust exiting the cast manifold exhaust outlet for controlling exhaust gas temperatures and both water and exhaust mixture eventually exits through the transom exhaust, carried by the continuous exhaust-gas stream. Pinching this upper nipple hose that delivers water from the exhaust manifold casting to the exhaust pipe will also stop water from flooding the exhaust system.

So either one or even both, may be pinched.

Hey, so I just got a boat today and am learning all this stuff (let me know if theres anything else to be worried about). Call me a noob but was just wondering if sitting out in the middle of the lake is ok as well? Wouldnt water still be able to fill up if you're just sitting there not moving it?

 

[borismartin]

Hey, so I just got a boat today and am learning all this stuff (let me know if theres anything else to be worried about). Call me a noob but was just wondering if sitting out in the middle of the lake is ok as well? Wouldnt water still be able to fill up if you're just sitting there not moving it?

Hey!

First off congrats on your new boat.

With regards to your question on if you need to be worried about this while you're just bobbing around/sitting on the lake, the answer is NO.

This is only a viable concern IF the boat is being moved at a decent speed, and not simultaneously running. If you're just sitting around there isnt really a risk that you'll have water backing up into the exhaust cooling circuit.

With regards to your other question on Do's and Don't probably best to have a read through this thread (http://www.seadooforum.com/showthread.php?80385-List-of-things-NOT-to-do-to-your-Jet-Boat) as there are some great points on things you should keep in consideration and watch out for.

Congrats again, enjoy the new boat!

 

[alindley]

Hey!

First off congrats on your new boat.

With regards to your question on if you need to be worried about this while you're just bobbing around/sitting on the lake, the answer is NO.

This is only a viable concern IF the boat is being moved at a decent speed, and not simultaneously running. If you're just sitting around there isnt really a risk that you'll have water backing up into the exhaust cooling circuit.

With regards to your other question on Do's and Don't probably best to have a read through this thread (http://www.seadooforum.com/showthread.php?80385-List-of-things-NOT-to-do-to-your-Jet-Boat) as there are some great points on things you should keep in consideration and watch out for.

Congrats again, enjoy the new boat!

Thank you! I was scared at first having a 2000 sea doo rx that just became problem after problem, but was a great first run. 2012 sea doo speedster 150 255 SC. Was super wavy/had girlfriend and her sister in the boat, but hit 3/4 throttle for 10-15 seconds and she just ripped.

Def will be giving this a read.

Yea, I figured it would have to be moving for it to be a concern, but just wanted to make sure as most of the time I'm out I assume well just be hanging out/swimming/etc. Driving from place to place.

 

[Sportster-2001-951C-Stock]

I think you'll find the 2012 really is light-years ahead of your 2000 Seadoo but all marine power plants are subject to water damage obviously, one of the "enemies" so to speak.

Boris is absolutely correct, if the boat isn't moving at appreciable speed there will be no problem even in a fairly rough sea. The jet pump is shaped rather like a funnel and normally supplies cooling water by force while the engine is running, some of the water being pumped is directed through the exhaust system for cooling purposes and is actually injected into the exhaust gasses as they leave the engines cast manifold log to keep heat from damaging the exhaust piping components.

So because of the funnel shape of the jet pump when the boat is being towed some amount of pressure is built up within the jet pump and it's possible depending on speed, that water can flow the normal path through and into the exhaust system, filling the piping completely with water. So please study carefully in case you do ever need to have your disabled boat towed by another vessel, and beware that you should be prepared to pinch at least the water supply that comes from your jet pump for cooling the exhaust system.

If speed is kept low while towing, this is unlikely to happen but your owners manual does provide some detail concerning this very subject, so please be sure to read that section carefully.

The more you understand about your boat, the better you will be able to care for it, and the more trouble-free obviously. May you have many great days with friends enjoying the water!

 

[alindley]

I think you'll find the 2012 really is light-years ahead of your 2000 Seadoo but all marine power plants are subject to water damage obviously, one of the "enemies" so to speak.

Boris is absolutely correct, if the boat isn't moving at appreciable speed there will be no problem even in a fairly rough sea. The jet pump is shaped rather like a funnel and normally supplies cooling water by force while the engine is running, some of the water being pumped is directed through the exhaust system for cooling purposes and is actually injected into the exhaust gasses as they leave the engines cast manifold log to keep heat from damaging the exhaust piping components.

So because of the funnel shape of the jet pump when the boat is being towed some amount of pressure is built up within the jet pump and it's possible depending on speed, that water can flow the normal path through and into the exhaust system, filling the piping completely with water. So please study carefully in case you do ever need to have your disabled boat towed by another vessel, and beware that you should be prepared to pinch at least the water supply that comes from your jet pump for cooling the exhaust system.

If speed is kept low while towing, this is unlikely to happen but your owners manual does provide some detail concerning this very subject, so please be sure to read that section carefully.

The more you understand about your boat, the better you will be able to care for it, and the more trouble-free obviously. May you have many great days with friends enjoying the water!

Thank you so much, definitely have boosted my confidence a bit! The only other concern I have that I can think of pertaining to this subject is I will be going to my buddies cottage in a few weeks and I will have to be leaving the boat in the water for a few days straight, I obviously know it will be fine, but I have read that it isn't the best idea to leave it in water all the time. What would the reason for this be? And is there anything I should prep for? I bought like 6 bumpers yesterday for anytime I need to dock it hahah

 

[Coastiejoe]

Thank you so much, definitely have boosted my confidence a bit! The only other concern I have that I can think of pertaining to this subject is I will be going to my buddies cottage in a few weeks and I will have to be leaving the boat in the water for a few days straight, I obviously know it will be fine, but I have read that it isn't the best idea to leave it in water all the time. What would the reason for this be? And is there anything I should prep for? I bought like 6 bumpers yesterday for anytime I need to dock it hahah

The Carbon Seal (CS) is designed in such a way that it leaks. The question is, to what degree? Boats are heavier than skis but use the same CS. As such, it is common for them to leak at a faster rate as compared to a ski. If it sits overnight it is possible to leak to the point that the boat sinks.

Solution is an Automatic Bilge pump and a good battery.

 

[alindley]

The Carbon Seal (CS) is designed in such a way that it leaks. The question is, to what degree? Boats are heavier than skis but use the same CS. As such, it is common for them to leak at a faster rate as compared to a ski. If it sits overnight it is possible to leak to the point that the boat sinks.

Solution is an Automatic Bilge pump and a good battery.

Oh wow, wasn't expecting this answer. Do you have any recommendations or links for this?

 

[Coastiejoe]

You can buy a bilge pump virtually anywhere marine products are sold. With with an internal float switch or an external one (that's the part that makes them automatic).

 

[Coastiejoe]

BTW, SeaDoo actually states in the manual that boats should not remain in the water docked overnight or for days.