# Water Pressure Help



## Smackdaddy53 (Dec 31, 2012)

Remove the hose end at the gauge and stick it in a little catch cup and run the outboard until 100% water comes out (zero air bubbles) and immediately screw it back on the back of the gauge. If that line gets air in it the water pressure will not register because air can be compressed, fluid can’t. Once that hose has water in it it will not drain out the block side because the gauge is like holding your finger on top of a straw and pulling it out of a glass of water, the vacuum keeps it in place.


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## Rayreds (Oct 24, 2016)

Smackdaddy53 said:


> Remove the hose end at the gauge and stick it in a little catch cup and run the outboard until 100% water comes out (zero air bubbles) and immediately screw it back on the back of the gauge. If that line gets air in it the water pressure will not register because air can be compressed, fluid can’t. Once that hose has water in it it will not drain out the block side because the gauge is like holding your finger on top of a straw and pulling it out of a glass of water, the vacuum keeps it in place.


Water pressure gauges don’t work off of water pressure. Water ,salt, will ruin a gauge. If these port on the motor plunges up with trash or corrosion it will not work. Had aYam that I had to clean out the port. Hole in aluminum block was to small and would plug almost after every trip. Good luck!


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## Smackdaddy53 (Dec 31, 2012)

Rayreds said:


> Water pressure gauges don’t work off of water pressure. Water ,salt, will ruin a gauge. If these port on the motor plunges up with trash or corrosion it will not work. Had aYam that I had to clean out the port. Hole in aluminum block was to small and would plug almost after every trip. Good luck!


I guess I’ve been doing it wrong all these years, I need to rethink my strategy!


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## m32825 (Jun 29, 2018)

Has the pressure gauge ever worked properly?


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## lemaymiami (Feb 9, 2007)

The claim that “water pressure gauges don’t work off of water” is flat wrong…. I won’t rig a skiff without a water pressure gauge - they’re that important… Every water pressure gauge I’ve ever had ( since 1974) is only powered by the water (fresh or salt…) that comes from that motor… Yes they’ll also have wiring - but that’s only to power the light needed to illuminate the gauge for night running.


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## sjrobin (Jul 13, 2015)

Water pressure gauges should be considered secondary, easily overlooked by the operator and easily plugged by debris/deposits. Most new outboards are equipped with audible alarms and power reduction to keep us from destroying the engine.


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## Flyer (Mar 27, 2019)

Yes, the gauge used to work. It read about 3 at idle and 8 or 9 while running. I first noticed that it didn't work when I slashed it after the installation of pump and thermostat. It could be a coincidence or could it be related?


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## topnative2 (Feb 22, 2009)

Check the prostated bypass valve for leakage.


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## Smackdaddy53 (Dec 31, 2012)

sjrobin said:


> Water pressure gauges should be considered secondary, easily overlooked by the operator and easily plugged by debris/deposits. Most new outboards are equipped with audible alarms and power reduction to keep us from destroying the engine.


Water pressure is primary, high temperature shut down is secondary. If you notice low water pressure and shut down and resolve the issue before it gets hot you are ahead of the game. Take it from a guy with a five gallon bucket of customer’s burned up water pump parts.


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## lemaymiami (Feb 9, 2007)

Forgot to mention that what Smack said about bleeding the water pressure line to get that gauge working properly again - is right on the money... What he said about it being your primary defense against over-heating damage is absolutely correct as well. When I run at night - that pressure gauge is the only thing I really pay attention to... If you wrap a plastic bag or weeds around your lower unit while running - your water pressure will go to zero - but it will still take a minute or two for your motor to begin overheating... Catch it when it happens, drop down to idle and clear anything obstructing your cooling water pickup and you'll never fry a motor. Waiting until your overheating alarm goes off (and your motor goes in to SLOW mode) just isn't good enough as far as I'm concerned... Of course I have to run day after day - and if you ever damage your motor by overheating it... No warranty that I know of will cover it...


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## Rayreds (Oct 24, 2016)

lemaymiami said:


> Forgot to mention that what Smack said about bleeding the water pressure line to get that gauge working properly again - is right on the money... What he said about it being your primary defense against over-heating damage is absolutely correct as well. When I run at night - that pressure gauge is the only thing I really pay attention to... If you wrap a plastic bag or weeds around your lower unit while running - your water pressure will go to zero - but it will still take a minute or two for your motor to begin overheating... Catch it when it happens, drop down to idle and clear anything obstructing your cooling water pickup and you'll never fry a motor. Waiting until your overheating alarm goes off (and your motor goes in to SLOW mode) just isn't good enough as far as I'm concerned... Of course I have to run day after day - and if you ever damage your motor by overheating it... No warranty that I know of will cover it...


Sorry no water in my gauges !!!! Yes the water pressure does compress the air in the line and causes the needle to move. Pull the hose off the motor and blow in it and you'll make the needle move. much like a tire gauge works. I have never bled and water pressure gauge line in my life. water in gauge no Bueno. I still say the block is stopped up.


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## Smackdaddy53 (Dec 31, 2012)

Rayreds said:


> I’m not saying your method does not work, I’m arguing efficiency. Sorry no water in my gauges either, I have had the same manual Yamaha water pressure gauge on my skiff since I installed it!!!! Yes the water pressure does compress the air in the line and causes the needle to move. Pull the hose off the motor and blow in it and you'll make the needle move. much like a tire gauge works. I have never bled and water pressure gauge line in my life. water in gauge no Bueno. I still say the block is stopped up.


No one said to let water inside the gauge but for the most accurate pressure reading you want as little air in that line as possible because the laws of of physics are never wrong. Do you know why a pressure sensor in the block is more accurate than a mechanical gauge? Because the pressure sensor is sensing pressure at the source, not with ten feet of air filled tubing between the source and the device reading the pressure. The water pressure in the cooling jacket has to compress the air in the line to the gauge before it reads it and your mechanical gauge will show a lower pressure the more air is in between it and the pressurized fluid. Do you know why one of these huge natural gas compressors I’m parked ten feet from right now can’t have fluid in the valves? Because fluid does not compress but gas (air) can. It will explode if there is fluid in it and kill me and anyone on location.
He probably does have a blockage at the powerhead fitting but I’m arguing the method to attain the most accurate pressure reading. 

I’m patenting a marine outboard product and system where water pressure is the biggest factor and have over a decade of experience in the field working on, building systems for and monitoring fluid and gas so I would hope I have some sort of real world understanding of what I’m trying to convey here.


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## Rayreds (Oct 24, 2016)

Smackdaddy53 said:


> No one said to let water inside the gauge but for the most accurate pressure reading you want as little air in that line as possible because the laws of of physics are never wrong. Do you know why a pressure sensor in the block is more accurate than a mechanical gauge? Because the pressure sensor is sensing pressure at the source, not with ten feet of air filled tubing between the source and the device reading the pressure. The water pressure in the cooling jacket has to compress the air in the line to the gauge before it reads it and your mechanical gauge will show a lower pressure the more air is in between it and the pressurized fluid. Do you know why one of these huge natural gas compressors I’m parked ten feet from right now can’t have fluid in the valves? Because fluid does not compress but gas (air) can. It will explode if there is fluid in it and kill me and anyone on location.
> He probably does have a blockage at the powerhead fitting but I’m arguing the method to attain the most accurate pressure reading.
> 
> I’m patenting a marine outboard product and system where water pressure is the biggest factor and have over a decade of experience in the field working on, building systems for and monitoring fluid and gas so I would hope I have some sort of real world understanding of what I’m trying to convey here.


Do as you wish but I'm Not bleeding mine. Water pressure gauges on boat are not calibrated and should be used as a indicator only. Any change plus or minus should be investigated as to the cause. I'm sure that in the oil and gas field pressures are critical. Not so much on a outboard motor. Just my 2C worth. Bleeding the line is not going to make the needle move if there is no liquid in line ....Just trying to help.


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## finbully (Jan 26, 2013)

Rayreds said:


> Do as you wish but I'm Not bleeding mine. Water pressure gauges on boat are not calibrated and should be used as a indicator only. Any change plus or minus should be investigated as to the cause. I'm sure that in the oil and gas field pressures are critical. Not so much on a outboard motor. Just my 2C worth. Bleeding the line is not going to make the needle move if there is no liquid in line ....Just trying to help.


Carry on as you see fit. Pretty sure the responders have said basically the root cause of the gauge issue should be figured out and recommended how to do that.


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## lemaymiami (Feb 9, 2007)

That’s okay… my kids and grandkids don’t listen to me either.


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## Smackdaddy53 (Dec 31, 2012)

Rayreds said:


> Do as you wish but I'm Not bleeding mine. Water pressure gauges on boat are not calibrated and should be used as a indicator only. Any change plus or minus should be investigated as to the cause. I'm sure that in the oil and gas field pressures are critical. Not so much on a outboard motor. Just my 2C worth. Bleeding the line is not going to make the needle move if there is no liquid in line ....Just trying to help.


Bleeding the line will be mandatory soon. All jokes aside, no one told you you had to bleed it and if you read my posts I also believe he may have a restriction in the water jacket fitting.


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## Flyer (Mar 27, 2019)

*Update on the water pressure problem......*I took off the "tee" and the hose from the block and the hose to fuel vapor. Put muffs on the motor and cranked it up. NO WATER came out from the port on the block but the fuel vapor line blew a little air. Why no water came out of the port at the block is beyond my pay grade for sure. Any more ideas????


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## Rayreds (Oct 24, 2016)

Flyer said:


> *Update on the water pressure problem......*I took off the "tee" and the hose from the block and the hose to fuel vapor. Put muffs on the motor and cranked it up. NO WATER came out from the port on the block but the fuel vapor line blew a little air. Why no water came out of the port at the block is beyond my pay grade for sure. Any more ideas????


Pull the fitting out of the block and see it you can blow through it. If clear, the stoppage is in the block. A small drill bit turned by hand will help clear the blockage. Maybe a piece of leader wire to start. Followed by compressed air. if you don't have a compressor, you can buy a can of compressed air at a computer supply store. Or run water with the muffs. I like to get the trash out instead of forcing it back in.


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## MudSkipper (Jan 11, 2021)

Just find a real Texan to blow into the system. That will clear it out. Real Texans, with all their hot air, can blow into a bulls ass and crack his horns.


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## Flyer (Mar 27, 2019)

The Case of No Water Pressure has been solved.....My neighbor and I tried reaming the port to the block with weedwacker line again, then used compressed air, and then some light wire leader all to no avail. Then we sprayed CRC 6-56 Zero Voc and reamed it out with thicker wire - more like a coat hanger - and within minutes the corrosion broke free. Put the muffs on and ran it for awhile and it had water pouring out. Reassembled all the tubes from the "tee" and voila....my water pressure gauge is working again. Thanks to everyone for their advice and suggestions. The case is closed ...for now.


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## Smackdaddy53 (Dec 31, 2012)

Flyer said:


> The Case of No Water Pressure has been solved.....My neighbor and I tried reaming the port to the block with weedwacker line again, then used compressed air, and then some light wire leader all to no avail. Then we sprayed CRC 6-56 Zero Voc and reamed it out with thicker wire - more like a coat hanger - and within minutes the corrosion broke free. Put the muffs on and ran it for awhile and it had water pouring out. Reassembled all the tubes from the "tee" and voila....my water pressure gauge is working again. Thanks to everyone for their advice and suggestions. The case is closed ...for now.


Good deal! I recommend flushing after every trip with Salt Terminator or SaltAway to dissolve the remaining crusties in the system and keep it clean. Cheap insurance...I got my guide buddies using it years ago and their outboards are super clean inside when they sell them.


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## Flyer (Mar 27, 2019)

Will do.......Thanks,Smack,for all your help and tips


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## Smackdaddy53 (Dec 31, 2012)

Flyer said:


> Will do.......Thanks,Smack,for all your help and tips


Any time, save my contact.


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