Can I do this? Flushing question

[shawn_NJ]

I have a kawi 750 motor that is overheating while riding. It is boiling water on the head, pretty bad. I know you are supposed to run the ski when flushing it out, but I really want to flush the motor out good for an extended period. Its setup for single cooling. Can I disconnect the water line from the head that feeds the pipe, and hook that directly up to the garden hose? And leave it backflushing through the head and out the pump.... for like 10-15mins with the motor off? That way all the pressure is pushed through the motor and not partially out the pisser. No water will make it to the exhaust because that will be disconnected, so it should not fill the exhaust up. I also plan on hitting the motor with compressed air.

 

[stanton]

why run it when off?
either the backflush will knock whatevers loose right away or do nothing at all, leaving it for an extended period wont loosen up a rock any more.

 

[shawn_NJ]

I flushed it running on the hose, but alot of water pressure is lost out the exhaust. Thats why I figured going full blast through the motor might help. If its sand clogging something, a long flush my help.

 

[227]

I wouldn't do that. If your cooling system is clogged with sand its problably from build up over a long period of time and I doubt that would clear it out. More than likely you picked up a small pebble that suck in the 90' fitting on your pump anyway.

 

[shawn_NJ]

Strange thing is that is pisses pretty good. Rear cylinder doesnt get that hot. I'm going to pull the head and check the jacket for anything jammed in there.

 

[227]

Strange thing is that is pisses pretty good. Rear cylinder doesnt get that hot. I'm going to pull the head and check the jacket for anything jammed in there.

Honestly dude I'm just guessing but that would be consistant with some kind of sand water blockage though. Water comes in the tapped fitting at the rear of exhaust manifold so the rear piston gets coolng first, over time sand/shells, etc settles in the water jacket in the front part of cylinder were theres less water movement/pressure making front cylinder get hot. Items larger than sand like small pebbles tend to get stuck in the fittings and usually don't make it into the water jacket themselves. Check the 90" fitting on the pump first and then the fitting at the entrace to the exhaust manifold (Check both visually and by putting air through them), if its not there then you'll have to start dissassembling. You may need to pull your ex manifold and head.

 

[shawn_NJ]

Kawi's stock water fitting is dead center on the exhaust manifold... so if enough cooling water is making it to the rear cylinder and not the front, the blockage is probably at the head or where the exhaust manifold bolts to the front cylinder. Going to mess around with it tomorrow. I know an extended flush is probably not going to fix it, but my question was can it actually hurt anything?? I dont think it can, but just wanted to bounch the idea off everyone else. This ski has seen ALOT ALOT of sand, so I thought a long flush and tapping the cylinder with a rubber mallet and some compressed air through the fitting might do it good. Odds are I am going to have to pull the ex manifold and or head tom.

 

[tom21]

its worth a try but I dont think its gonna work. that sand settles pretty tight and when it dries and the crystals grow its almost like rock. the water pressure will not be focused to the point it will move anything, maybe a small amount from the top that is already loose but if that is full its not gonna do it. its just a gasket and a few minutes of your life. you may even find other things wrong and you will be glad you checked. just my .02

 

[WaveDemon]

its worth a try but I dont think its gonna work. that sand settles pretty tight and when it dries and the crystals grow its almost like rock. the water pressure will not be focused to the point it will move anything, maybe a small amount from the top that is already loose but if that is full its not gonna do it. its just a gasket and a few minutes of your life. you may even find other things wrong and you will be glad you checked. just my .02

Tom is 100% correct... as usual.

 

[tom21]

lol only because I have tried to work around problems before too! trust me I have got to be the laziest short cut taking, f it - it will work guy when it comes to my skis. In the end we all know its best to do it right. Im just worried there is some corrosion and its not sand its water in the cylinder. and not the jacket- on the piston!

 

[shawn_NJ]

I would just rip the head and manifold off, but I am going down to FL on thursday and do not have any new kawi head gaskets here. Thats why I am trying to fix it the nonintrusive way...lol I might just swap the motor out with my spare 750.

 

[shawn_NJ]

Well flushing test revealed the problem. On Kawi exhaust manifolds the water jacket goes all the way to the top where it meets the headpipe. The 3bolt gasket blew out and was letting water free flow from the manifold into the headpipe, robbing the motor of cooling water. This is why the ski pissed normal. New GOOD gasket between manifold and headpipe, and hope for the best.

 

[WaveDemon]

I've heard of this problem. I'm surprised you didn't have some water ingestion symptoms

 

[shawn_NJ]

The gasket was intact around the very inner part of the manifold hole and outer portion. It just blew out where the water jackets line up. I sealed the gasket up good with high temp silicone when it was installed, and I am guessing thats what saved the motor from filling up. I used cheap "cut your own" gasket material that did not have the metal layer in it, so I am guessing thats why the water jacket portion blew out. Wish I had a solid top manifold to replace it with, but I sold alot of my kawi parts. I think a quaility reinforced gasket would not have had the same problem. I disconnected the hose going to the headpipe and turned on the garden hose, when it was connected to the head. Theoretically no water should have gone to the exhaust. Well tons of water came out of the pisser, so I knew water was making it thought at the top of the exhaust manifold, as its the only way water could have made it to the headpipe.