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Discussion Starter #1
Howdi,
looking for a cooling system diagram that shows the whole system and the components. I do have service manual but its in bits and pieces. Looking for an overall diagram that can help me understand the system and identify components and locations.
thanks
jason
 

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There is no single diagram of the entire cooling system. The pump, exhaust, and power systems are all involved, so you just have to piece it all together from the different diagrams in the service manual. If you have a specific question about the cooling system, let me know.

Here is a link for a down-loadable version of the service manual: LIT-18616-FX-11.rar
 

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Discussion Starter #3
cooling diagram

Hi Earnest,
thanks for your reply. sounds like you know this thing pretty well, it would be awsome if you could maybe do a chicken scratch diagram with the main components called out, simple version offcourse that I can at least follow would be great helpl
thanks again for your help.
thanks
jason
I just need to be able to follow the cooling system and identify the main components
 

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Unfortunately the cooling system on these 4 strokes is a complex maze. It is not a simple loop where the water comes in, cools the engine, and exits. There are branches and splits in the system for cooling various components. The best way to get an idea of how the system works is to trace the hoses that can be seen using the service manual where they enter and exit the engine and exhaust system. Much of the cooling system cannot be seen as it is running through water jackets around the cylinders, through the exhaust manifold, and inside the exhaust system. Look at the "Cables and Hoses" diagrams in the service manual.

If you really want to get an idea of how it works, get yourself a flashlight and the service manual and trace hoses. Remove the metal deck beam (4 bolts) so you can see down behind the engine area. Start at the cooling water inlet hose which enters the hull from the jet pump through the transom on the port side near the bottom of the transom. This hose is easy to find since it joins the flush hose at a "Y" joint, so you can just trace down the flush hose to the "Y" joint then trace the inlet hose to the engine. The service manual will show you the direction of water flow in the hoses. Cooling water enters the ski through 1 hose, but exits at at least 4 different locations. Once you have traced the entry point and the 4 exits and understand where the water came from for each point, you will have a pretty good understanding of how the system works.
 

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Discussion Starter #5 (Edited)
Clamping inlet during flushing

Thanks Gents for the info,
So my next question is, with the maze of cooling system, and the fact that cooling water inlet and Y points for flush inlet are lower than the engine, wouldnt it make sense to clamp the inlet line (before Y) when youre flushing the engine. I would imagine with the inlet line in the path of least resistance, and there is no pressure fron the jet, most of the Rust removing solution and water is not going to reach the higher points of the engine.
I appreciate feedback.
thanks
jason
 

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You are correct. Much of the water flowing in through the hose goes right out the back of the ski through the inlet hose, and never circulates through the engine. That is why guys that try to put antifreeze in through a funnel are really just dumping most of the antifreeze on the ground. Fortunately, Yamaha 4 strokes are self draining, and really don't need antifreeze anyhow. The problem with water not circulating through the engine is compounded if the ski is sitting nose high and not level.

You can pinch off the cooling water inlet line with a pair of pliers when flushing to get the water flow into all parts of the engine. On my ski, I get water out of both port and starboard overflow ports on the hose without having to pinch off the inlet line (probably has to do with water pressure from the hose).

If you do pinch off the inlet water line when flushing, you may not need as much water pressure on the hose, and be sure that the engine is running before you turn on the water and visa-versa, since it would be easier to push water into a cylinder this way.
 

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Discussion Starter #7
Awsome,
thanks a bunch for the feedback Ernest. I ll try this tommorrow and let you know how it went.

jason
 
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