Dual Engine Flush - Overheat

[deancastor]

I was flushing both engines at same time using a hose splitter T-valve. Was also adding Salt Away mixture at same time. At about 15 minutes right before I was about to shut down one engine started over heat alarm. I cut off immediately and hopefully no damage but I wondered if I went too long, maybe water pressure wasn't high enough, or any other reason I can't think of. Help! Once again!

 

[Blazin14]

Water pressure not high enough. Same thing happens to me on one engine. I have poor pressure at my house.

 

[deancastor]

The water pressure at the marina seems strong, but it's possible I didn't have valve open all the way. Also, does it reduce when doing two at a time?

 

[Scottintexas]

I'm no engineer/physicist but I'm going to guess and say the splitter does reduce the pressure going to each engine.

I wouldn't worry about the overheat alarm, there's a big window between alarm, engine going into limp mode and then engine damage,

 

[deancastor]

Thanks. That makess me feel better. My engines were off within 10 seconds at most. Just cut the water and cut the engines.

 

[MrMoose]

I had the same thing happen to me once, no splitter, just running one engine. At the time, I did notice that my cooling stream exiting the side of the hull was at a trickle, but lots of water was coming out of the exhaust. I adjust the water flow until I get a cooling stream that is similar to the one that I get when I run the boat in the lake, and it doesn't over heat.
BUT I've always wondered if you can damage the engine if you have too much water pressure in the flush hose...???? I've always been a little worried about putting too much water pressure into the cooling system. Looking for insight!

 

[deancastor]

I have same situation. Seems like all water is coming out exhaust when I flush out of water too.

 

[Scottintexas]

https://jetboaters.net/faq/how-does-the-cooling-water-flow-in-my-yamaha.101/

it's made to come out the exhaust, check out this great video from our FAQ section the member BuckBuck made,

you can't have to much pressure from the hose because the water can only intrude into the cylinders via the exhaust channel being forced backwards // edit - and with the engine running the exhaust pressure keeps it flowing out //

 

[MrMoose]

https://jetboaters.net/faq/how-does-the-cooling-water-flow-in-my-yamaha.101/

it's made to come out the exhaust, check out this great video from our FAQ section the member BuckBuck made,

you can't have to much pressure from the hose because the water can only intrude into the cylinders via the exhaust channel being forced backwards // edit - and with the engine running the exhaust pressure keeps it flowing out //

Are you sure? That video is about the MR1 engine. All I'm saying is that when I run my boat on the water, water shoots out of the side of my hull, which I believe is the cooling water exit. If I hook up my boat to a marina hose with a salt away unit, nothing comes out the side, and my engine will eventually overheat. If I'm at home and I turn up the water pressure high enough, water will squirt out the side port, and my engine won't overheat. So, I assume that water should be shooting out the side, but the big question is, if I open up my hose full rip at home, will I damage the engine while it's running?

 

[CrankyGypsy]

(for the M-1 at least) the flush inlets/tubing are too restrictive to allow a garden hose to fill the system ...add the Salt Away mixer and it's even less. if the system can't fill, it won't have residual volume/pressure to flow from the pee holes. I'm baffled: this has to be an engineering oversight as it makes it impossible to thoroughly clear salt from the jackets if it can't even fill them.

 

[Scottintexas]

Are you sure? That video is about the MR1 engine.

I am not positive enough to tell you.

@SCSTWG @Cobra Jet Steering LLC @swatski
Can one of you or anybody else who might want to chime in confirm for MrMoose that the 1.8 cooling system is
1. exactly the same as the MR 1
2. similar except for small differences (what might that be)
3. totally different


As far as how much can you turn your hose on at home I guess we would have to know how much PSI that would be. I turn my hose on all the way but I don't know what pressure it is. As I understand it the pressure of the exhaust gas keeps the water looking for the way of least resistance which is out the back.

 

[Cobra Jet Steering LLC]

All I know is that when I flush the 1800 engines the water comes out the side like mad however this really isn't important because the water is coming from a hose rather than the jet pump, the water you see exiting the pump is also from your hose going the opposite direction it would travel if it were the pump doing it so you are actually back flushing the pump filter .
As long as you see water coming out the side when your engines are running in the water you are ok , they were designed to let you know visually if your pump was clogged or the intake was clogged during normal operation . I take a look at the water coming out the pee holes when I hit some weeds or trash so I know the water is still flowing through the cooling system. Your alarm will go off when you are having an issue with a lack of cooling water in the engine. And your engine will go into limp mode so while we are on this subject let me say for those who may not already be aware of this, LIMP MODE IS NOT SAFE MODE!!! Do not keep driving the boat with that engine running ! You need to stop a.s.a.p. and find the reason why your overheat alarm and or your limp mode are activated, continuing to run will cause engine damage, warp a head , crack a head between the valves , or perhaps you have some other malfunction that will cause all sorts of damage that will probably not be covered by your warranty.

 

[Britboater]

I'd just flush each engine individually, 15 mins is way too long so I can why you'd want to dual flush but with using salt away 5 mins each engine is more than enough. There, I've gone and saved you 20 mins .

 

[BlacklimitedS]

You should never run the engines longer than 5 minutes out of the water. The impellers use the water as cooling between the wear rings. Also never use a Y fitting. Although it is faster the pressure is too low. Each engine should be done separately. You didn't damage the engines as you shut them down right away. Depending on how many times you have ran the engines out of water for an extended period of time you could have excessive wear in your pumps.