Does it have a regulator. I would think it would have to have something otherwise you'd be blowing gaskets.


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Put one on! GT has lots of info on this subject on here....


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i dont see how cold water from a hose would allow any motor to build heat unless you had the hose turned wayyyy down. 

tuning for temp on the trailer is compleeeeetely different than tuning it on the lake.  not to mention lake water temp can change and you might need to open or close it some to adjust. 

not only should you have a gate valve to control engine temperature, but you should have it there in case you have a leak somewhere in your cooling system.  a 1/2" hose will flow some serious water if you snagged a hose on a beach chair or something.  you'd sink in minutes and if you started the boat to power it to shore, you'd have a 60+ psi 1/2" leak. 

Another question I've always wondered is can you turn the hose on first and then start the boat ? I've always started the boat then turned the water on


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If you're running headers, you can fill cylinders with water before you get the boat fired up.  Always start the motor then turn on the water.  Turn off the water then kill the motor. Water running in an engine that isn't running is not good.
 The gate valve to control water temp/ pressure debate is as old as the Ford Chevy debate.  My.02 is the gate valve is simply a safety device to stop water from coming in the boat if a hose happens to break like Kay0tyk explained .  Jet boat motors run cold and that should be taken into account when the motor is built and the tolerances are set..
 Oil temp is much more critical.  I'm always afraid if you close down the valve to create heat you may be over restricting the volume and creating steam pockets and hot spots.  When do you adjust your valve at idle, 1/2 throttle, full throttle?  Each one of these settings is going to create a different temp.
 I think 1 line in and 2 or 3 lines out is the simplest way, and understand that 130*-150* in a boat with an open cooling system is normal.  I personally regulate my water pressure by having 2 dump lines that are -10 plus my headers.  If you give your cooling system multiple exits, it can't over pressure, and you can still keep the water volume up. It's more important to warm the oil before hammering it than water temp.
 But That's just me.

Gate valves suck.   

Sometimes they work and they are cheap but not made to control flow and no one ever said shit got water in my block cause my regulator let me down.   How many milkshakes have been caused by boats with gates only off the pump???  Ur house water hose is like 30 psi ur pump makes 200 psi.  So trailer test dont count. 

I always use a hydraulic hose from a push lock fitting in the pump to a gate valve, I don't do rigid pipe in the pump because of the chance of breakage.

A gate valve works great. Once you get the boat in the water, you adjust it at idle, let it get the outlet temp to about 150*F and it should be fine unless it is piped horribly wrong. The water temperature will tank as soon as the engine speeds up.

Like icecreaman says, ALWAYS start the engine first, then water on, when done, water off then engine off. It takes about two seconds for this to go horribly wrong.

Also, if it wont stay running because of a tune issue or something, get that straightened out first. You do not need to run water if you are only running it for a minute or two.

I recommend backing off the shaft packing on the pump if running it dry, it helps keep the rope seal from burning up. The packing should only be tightened in the water and just tight enough to see about a drip every couple minutes.

The gate valve debate is silly because NOBODY has ever come up with something better with fewer moving parts. Until that happens, I will use a gate valve over anything else. So simple it's almost stupid. 

GT

Heres another

I really don't car what ANY of those say...

The regulator you have on your boat is not rated for untreated water either, yet, here we are. 

These valves have been used on these boats for over forty years, so for you to say they don't work is the stupidest thing I have ever heard.   

Somehow I knew this was going to happen. 

GT

experience over knowledge sometimes huh GT. me personally I will run both gate and pressure relief because with your LIFE and others you cant be to safe gate to reduce and shut off flow in an emergency relief to help my motor out 90 to 100$ for both whats your boat or lives worth..

Did u adjust it back down after runnung at 2grand when it went up to 190

Are u running logs or over transom headers