"Water Pressure 101"- Poppet Valves and Variables with Water Pressure

[198elite]

Oh boy, I'm running at idle 106 and lower. You think I might need thermostats?
Will it hurt the motor? It seems to be running good.

[EuropeanAM]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 198elite &raquo;</TD></TR><TR><TD CLASS="quote">Oh boy, I'm running at idle 106 and lower. You think I might need thermostats?
Will it hurt the motor? It seems to be running good. </TD></TR></TABLE>

Yes, and YES.

If the engine cannot reach "operating temperature", you will have issues with the "controlled expansion" of the cylinder sleeves, leaving a strong potential for "cold seizure" (the piston expands faster than the sleeve, a ring hangs in a port (usually the exhaust port), and severe piston/ring/cylinder wall damage occurs).

[198elite]

Thanks for the help. I really appreciate it. I guess it 's time for me to get to work. Seems like an easy job. Wish me luck.HAHA. Thanks again.

Kevin P

[winged]

Don I have an 06 250 XS and at 5900 rpm I get a constant horn like hightemp.
Both the gauge and the Smart craft say 24 psi and 125 deg. Do I have a
thermostat problem? Thanks BK

[EuropeanAM]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by winged &raquo;</TD></TR><TR><TD CLASS="quote">Don I have an 06 250 XS and at 5900 rpm I get a constant horn like hightemp.
Both the gauge and the Smart craft say 24 psi and 125 deg. Do I have a
thermostat problem? Thanks BK</TD></TR></TABLE>

Unlikely, but not impossible. More likely would be an "air compressor overheat".

Start by looking for a good, steady stream of water from the telltale. The telltale stream is the "cooling outlet" for the air compressor on your engine.

[crawdad18]

I have a 2001 mercury 225 efi that lost the water stream from the back of the motor. It started by just kind of misting out then it was gone. came back for a minute and then gone again. i have not lost any water pressure. i am still getting around 15-18 psi at wot. Does this mean i need to replace the impeller or is the line clogged to the water outlet? how do i go about unclogging the water outlet? thanks in advance for your help!

[EuropeanAM]

Welcome to BBC!

Your scenario could be EITHER, or BOTH.

Suggest cleaning out the telltale fitting, and the tube.

Also, if you've not replaced your water pump in the LAST YEAR- I'd STRONGLY urge you to do it now.

These engines are capable of making significant "ram pressure" at WOT, and water pressure readings at WOT can sometimes be "deceiving" in regards to the health of the water pump itself.

[crawdad18]

thank you. i have read that replacing the water pump is not a hard task. is there anything specific i need to do when removing the lower unit? I know you have to remove all bolts and such and make sure it is in forward gear. Is there anything other than that i must do? Thanks

[EuropeanAM]

Here's a nice, well detailed outline of the steps and tools required (compliments of Sherm@ Sherm's Marine):

http://www.bassboatcentral.com/sttipswp2.htm

[crawdad18]

thank you for all your help

[Reelsore]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 492slayer &raquo;</TD></TR><TR><TD CLASS="quote">All this sounds interesting, but for me, I have no issues with WP at WOT with my 3.0L EFI (20-25+ lbs @ WOT). I do have the Poppet Valve kit from Eric Simon, and it will pump a 1" stream of water out the back of the motor that looks like a fire hose. I have had no issues with overheating, and with this kit, I get an increase in performance from having the water go out the rear, rather than through the exhaust column. </TD></TR></TABLE>


Hey Don, I've read this whole column which I must add is great information, but what is and where is this poppet valve yall are referring too? Also read where you stated 25 psi is max water pressure that it can safely handle, I am running 25-30 psi sometimes even higher. If I raise the motor as suggested to lower the ram effect the boat falls on its face; TR20X2 2007 250 pro xs 10" jp. Currently at 3.5 in below the pad is the sweet spot for this particular boat. Any lower it becomes extremely violent. 492slayer said he used a poppet valve kit he got from Eric to lesson the WOT water pressure, is this something I should look into? Thanks again for all the information on this site. Oh by the way, I am not getting any alarms on the MercMonitor, I am just wondering. Thanks Ashley

[F150owner]

Tonka,

You can see the poppet valve assy when you take the cowling off and look down into the starboard side of the engine. You will see, on the side of block inside the lower cowling, a plate that has two bolts. It seems to be by itself. This is the poppet assy.

To see the gory details, get your engine serial, then come back here and go to this link: http://www.mercurypartsexpress..._help

Once you enter your engine S/N, the application will display your specific engine. On the left pane of the application window, choose "Exhaust Plate". Once that diagram comes up, you can use your mouse on the actual photograph/diagram to move/drag the picture around.

You will see what looks like an exploded view of the Poppet valve on the side of the block. It has a spring on it.

If I were you, I'd not mess with the poppet and thermostats unless you are absolutely, positively sure your engine isn't running right which could be exhibited by other symptoms.

A week or so ago, I was convinced my engine was running too cool. My gauge was showing engine temp at 98-100 running down lake in 55 degree river water but showing completely normal operating temps at idle. After inspecting thermostats, and poppet, and doing water tests, it turned out to be nothing. Don and Mercury, and others told me my engine was fine. I'm showing 25+ PSI as well at wot.




Modified by Duane Harper at 5:00 PM 4/7/2010

[EuropeanAM]

+1 Duane!

Tonka: Might want to go back and read the ORIGINAL post. 25 psi of water pressure is NOT BAD (and if your setup is maximized and you have 29 with no problems.... don't sweat about it).

Of course.... I wonder what prop you're running that makes your boat "fall on it's face".... you might benefit from a prop with a little more bow lift.

That would be a subject for a "separate post".

[Reelsore]

Don, you must not get much sleep or are you a machine? on here @ 430 am and @ 1030 pm, WOW. I am in no hurry for my answers, just whenever is fine by me and I do understand that you have a full time hands on career and a life outside of this forum.


Sorry forgot the details, I'm running a 27P Tempest Plus, thinking about trying a 26P Fury. When I said that if I move the motor up anymore that the boat falls on its face, I meant I get way too much prop slippage and the bow drops and that wasn't even trimmed all the way up. You call feel it and you can watch the rpms shoot up but gain no speed. The only reason I asked was that you said 25psi is the max the poppet valve can handle before doing damage to it and also gotcha on the part about not sweatin it. I have no problems just trying to do PM and make sure it lasts.

Thanks Duane and Don, I will look it up to find the part location.

[EuropeanAM]

Poppet valve is located in the STARBOARD (right side) of the adapter plate, just below the "three relays".

You'll need to remove the staboard lower cowling to access it.

You might benefit from the Fury on your rig. I would also recommend inspecting your jackplate or setback plate to any signs that it may be "stretched or skewed" (altering the trim/transom angle).

[Dite]

IM sent....

[BILLY]

"3.0/3.2L & Verado 1.5 to 3psi at idle, 15 psi at WOT
2.5 Liter: 2-5 psi at idle, 12 psi at WOT."


2003 225 efi i THOUGHT THE BOOK SAID 8-10 AT 5000rpm

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by BILLY &raquo;</td></tr><tr><td class="quote">"3.0/3.2L & Verado 1.5 to 3psi at idle, 15 psi at WOT
2.5 Liter: 2-5 psi at idle, 12 psi at WOT."


2003 225 efi i THOUGHT THE BOOK SAID 8-10 AT 5000rpm

</td></tr></table>

Billy:

Water pressure on this model depends SPECIFICALLY on which gearcase the engine has.

Models WITHOUT low water intakes in the nose will have 8-12 psi @ WOT.

ALL LATER MODELS have low water intakes.... and carry the 15+ psi recommendation.

[Allsup]

Don,
Just this weekend I was trolling with the kids and noticing my water pressure was 1.4PSI and 125 degs. I didn't know what normal was, so I was searching your treads and here I am.
It's been 3 years and about 150hrs since my last impeller change. Is it time for a new impeller and or just a cooling system flush. It's been about three years since I did that too. Thanks

[EuropeanAM]

DEFINITELY past time for a water pump.