how much water presure

[dtr352]

I have a valve at the start of the water line coming from the jet. I can close it off any amount I want but how do I know the motor is getting enough water. My setup is plumbed very simply. Water comes in from the jet through the valve into a T, it then flows through the block and out the thermostat. One side of the thermostat goes to the headers and the other goes out a hole in the transom. There are valves like you would find on a garden hose at the start before the water goes into the motor and another on the hose that goes out the transom. Right now they are both open all the way. How should I determine where to run them. Thanks

[MudPumper]

You need to run a pressure regulator. do a search for pressure regulator and you will find everything you need to know.

[Squirtcha?]

J.A.P. (just another opinon). Not saying that mudpumper is wrong, just that I have another take on things.
The pressure regulator works and lotsa guys run em. Personally I never found a need for one.
Your setup will work just fine as it is. I'd leave the dump valve (water overboard) open all the way (in fact you don't even need a valve on that line).
As for the valve for the cooling water from pump to motor, Start closing it down a half turn at a time, then go run it. Your temperature gage should be around 160 degrees at idle. It'll fall to around 120 or so when you're running due to higher rate of water flow through the block. Don't worry about it, it'll be fine. It you didn't hit your 160 at idle, either open or close the valve some til you do. You can spend money on the regulator if you like. I just never found it to be a necessary (gotta have it) kinda thing.
I've run my boat like this for 6 years and have never had a problem. I pulled the motor two years ago for a rebuild, not because there was anything wrong with it, but because I wanted more power. The boat is a 1976 and the motor had never been rebuilt. The crank got turned .010" (first time) and that was it. The insides were great. No scoring/scuffing of cylinder walls, compression numbers were still well within spec, etc. etc. It probably would've run for another 10 years without a problem. That's why when I plumbed everything in stainless after the rebuild, I put it back together the same way as it was before (despite all the things I could've added to it). Classic case of "if it aint broke...........don't fix it).
Oh yeah, lots of guys like the thermostat setups too, and I'm sure they're fine. Definitely keeps your temps more consistent, but once again.............just something I didn't feel I needed.

[clownpuncher]

Intersting timing with this thread. My engine JUST got done by Paul Pfaff Racing. As part of the build, they installed a pressure regulator on the boat. Their reasoning was that with the engine's HP, the pump was producing a huge amount of pressure, somewhere over 130 psi. Way too much according to PP. With the new regulator, it'll be around 30 psi at WOT. Don't quote me on the specifics, but, you get an idea of what PP Racing thinks.
I'm sure Squirtcha has a good idea too. Maybe it depends on how much HP?

[Squirtcha?]

It's not so much a good idea.............just what has worked so well for me in the past.
You may be on to something with the hp thing. I'm only running 600 hp @ 5600 rpm and have no idea what the water pressure is at WOT. Don't have a gage on it, and might be too scared to look (if I did).

[dtr352]

Im only asking because I just bought the boat and Im getting water in the oil. I replaced the head gaskets but the problem is still there. The oil is milk white in 20 minutes. I estimate the motor to be about 420 hp but I don't know. Someone told me I could have to much water pressure. Could this be causeing the problem?

[Big Proppa]

Grainger has a regulator that alot of us run - I would put my money on your issue being that your pump is making to much pressure for your motor. Mine is set at 30 PSI also and from what I've heard a pump can produce anywhere from 150 to 250. Food for thought - I had the CP out last weekend, all my plumbing is done in the A-N push on fittings with rubber -10 hose. The back pressure off the regulator blew my lines off when I would run it around 6200 RPM. Needless to say they will all be braided before the holiday weekend. Just an FYI.
Good Luck -

[NAMarine]

dtr352, Is there an oil cooler in your system? Or maybe you have a bad intake manifold surface for the cooling ports.

[LVjetboy]

I'm with Squirtcha on this.
Although typical bowl pressure runs 130 psi for a mild build, you won't see anywhere near that pressure in your cooling system unless you completely shut off your dump line(s)...a dumb idea. Cooling pressure depends on power, then line sizes, fittings and valves...in other words your flow rate and line resistance. Not everyone's power or cooling system is the same as yours. So your setup is important.
For 420 hp, you may see something like 30 or maybe even 40 psi full throttle for a typical cooling system setup, but as I posted in the thermostat thread, it depends. Only way to know for sure is with a gage. Acceptable pressure depends on the condition of your engine and gaskets. An engine in good shape will hold to a higher pressure than car radiators are designed for (15 psi) maybe even to 30 or 35 psi but that's up there. My old engine would only hold to about 10-15 psi before leaking the seals. I knew this because I put a gage on. With the gage I could adjust flow to not leak the seals (milkshake) and still have reasonable idle temp.
As clownpuncher mentioned, full throttle power may require a regulator. But his power is higher than most, well above 420 hp. For example, on the lake with the new engine I'm running 6200 rpm on a b impeller which is about 650 hp. That's a "rated" power of over 700 hp. Yet no regulator. How could this be? Because my valve at the hardline is 3/8", my supply line is #8 and I run two #8 dump lines. Relatively small inlet valve and line (high resistance), two dump lines (low resistance.) Some only run one dump line. Some run 1/2" valve and #10 off the pump. Some run a (yikes) valve on their one and only dump line. Some logs some OT's. As you can see, the variables are endless and do indeed affect cooling supply pressure. That's why, "it depends"
With the hard line valve wide open full throttle I run about 20 psi. This is well within the pressure limits of my engine. And that gives me 150 F at idle and 120 F full throttle on a hot 100+ F day at Big River. Likely within temperature limits for full throttle detonation or idle hot spots in the heads (60 F below boiling temp at idle.) So for my cooling system, I think a pressure regulator is an unnecessary complication. And yes, a pressure regulator can fail. BTW, I did run a pressure regulator until I found I didn't need it. But another 75-100 hp would put me near 30 psi so there certainly is a power limit to non-regulated flow. Some on this board have more power so different requirements. I doubt you're close to that.
jer

[blownalky557]

The diagram below is what I use to keep the maximum water pressure to the engine at 15 PSI. This is just one example, but there are many other ways to accomplish similar results.
http://www.hotboatpics.com/pics/data/3021/1870jet_plumbing_3.jpg

[Taylorman]

Mine is very similar. I don't have the pressure relief bypass and instead of the spring loaded t valve i have and electric solenoid valve.
How many times do we have to talk about plumbing. This has got to be the most discussed topic on this forum.

[dtr352]

If I run the motor hooked up to the garden hose will I have too much pressure. I am trying to figure out why I milk the oil without tearing the motor apart. If it is a water pressure problem I can fix it without spending the time or money on gaskets and miscellaneous expenses. Head, intake, and exhaust gaskets are all new so I don't think this is the problem. With the dump valve open and my exhaust lines disconected will it hurt anything for water to run through the motor with it running or not. If the hose isn't on too high it shouldn't be that much pressure right. If it isn't too much water pressure causing my problem what else could it be. Would freeze plugs cause this problem. This is my first boat so I am not too sure about everything. Thanks for all the help.

[Taylorman]

Originally posted by dtr352
If I run the motor hooked up to the garden hose will I have too much pressure. I am trying to figure out why I milk the oil without tearing the motor apart. If it is a water pressure problem I can fix it without spending the time or money on gaskets and miscellaneous expenses. Head, intake, and exhaust gaskets are all new so I don't think this is the problem. With the dump valve open and my exhaust lines disconected will it hurt anything for water to run through the motor with it running or not. If the hose isn't on too high it shouldn't be that much pressure right. If it isn't too much water pressure causing my problem what else could it be. Would freeze plugs cause this problem. This is my first boat so I am not too sure about everything. Thanks for all the help.
You need to put a pressure gauge on your intake to see just how much pressure you have.
With the dump valve open and my exhaust lines disconected will it hurt anything for water to run through the motor with it running or not.
No it will not hurt.
Timing cover gasket could also be a place where water is getting into the oil. Also the pistons can suck water in if your t valve is not closing soon enough.

[HammerDown]

Originally posted by blownalky557
The diagram below is what I use to keep the maximum water pressure to the engine at 15 PSI. This is just one example, but there are many other ways to accomplish similar results.
http://www.hotboatpics.com/pics/data/3021/1870jet_plumbing_3.jpg
Except for the Enderle Popet Valve and extra T. this is also how my system is plumped. The 2 dumps is the answer for lower pressure.
Very seldom if ever see more than 12 psi measured at the intake manifold.

[American Turbine Man]

Check the drain holes in the bottom of the header tubes. It takes very little water running in through the exhaust valve, past the rings to milk-up the oil. Also do you ever run on the garden hose? If so remember; start engine, turn-on hose, turn-off hose, kill engine. Never have the hose on without the engine running.
ATM

[Taylorman]

Originally posted by American Turbine Man
Never have the hose on without the engine running.
ATM
Why not?

[clownpuncher]

Originally posted by Taylorman
Why not?
I'm thinking because the drain holes in the headers won't drain the water fast enough and water will soon find it's way to an open valve and into a cylinder = bad. With the engine running the exaust will keep water from entering the cylinder

[American Turbine Man]

I'm thinking because the drain holes in the headers won't drain the water fast enough and water will soon find it's way to an open valve and into a cylinder = bad. With the engine running the exaust will keep water from entering the cylinder
That is right! Plus you run the risk of hydraulic-ing a cylinder.
ATM

[Taylorman]

When i run mine on the trailer, water never goes to the headers. They stay dry. Im soon to rebuild my pump so my days of driveway noise are about over.
Originally posted by American Turbine Man
That is right! Plus you run the risk of hydraulic-ing a cylinder.
ATM
Off the subject but since we are talking about hydraulic-ing a cylinder. I was at the drag races in Houston a few weeks ago and got to see a alchohol dragster engine that hydrauliced with fuel. It blew the side of the block off. The guy said it happened to him twice that day. Ruined 2 Keith Black aluminum blocks.
Jet Boat HEHE.