Water pressure

[Karl]

I am having trouble with water pressure reading on my 94 Johnson 120hp. It use to ready 25# at wot now it pegs the needle 30+. this started after runing it & getting stuck in low water. Some people say I have a restricktion in thw motor but I don't understand how this could be because of how thw gauge is hooked up. It is t'ed in linw with the pee line. It seemes to me that if i had a restricktion in the motor then I would have low water pressure as not as much water flowing out of the block. I know that if I retrick the hose after the T the pressure rises.Sorry for the long post but AI need an answer.<br />Thanks

 

[Dhadley]

Re: Water pressure

I water still coming out the overboard indicator? The water cavity in the block is very large and not likely plugged. You may have some blockage in the thermostat area. Just pop the thermostat cap off each head and blow everything out. Just how low was the water and how bad were you stuck anyway?? Been there -- done that!

 

[Karl]

Re: Water pressure

Thanks for the reply Dhadley<br />I have already done that I also replaced both thermostats. I just don't understand how the water pressure could be reading hi when the gage is after the block, now if it was between the water pump & the block & I had a restiction in the block then I can understand it being high but wijth it being after then it should be reading lower pressure. I am no mechanic but???? <br />Thanks again Karl

 

[JB]

Re: Water pressure

Howdy Karl. You've got a really knowledgable wrench helping you out there. You may have overlooked one possibility. Suppose, when you got in the gunk and probably pumped some of it through the block and out the pee-hole, some got into the pressure guage and blew it's accuracy? It's a long shot, but it looks like you've covered all the normal suspects.<br /><br />Hope that's it.<br /><br />Happy boating.

<br />JB

 

[Dhadley]

Re: Water pressure

It does read between the pump and block if it's hooked up correctly. It's not like a crossflow that reads after the block. You may have to pull the heads if you are sure about the before and after readings. Is water still coming out of the indicator?

 

[Karl]

Re: Water pressure

Thank's to J.B. & Dhadley<br />Today I looked again & saw that the output tube for the gauge & pee hole is connected to the main block & not the head as I had assumed Ha I told you I was not a mechnic. Anyway this make more sense & you are right the something is pluged between the block & heads. Today I also removed the thermost covers & back flushed both heads,hope this works, if not then I will have to pay someone to remove both heads & clean water passages. <br />Oh by the way the water was about 6 inches & the rest was mud & goo. When I saw that is was getting to shallow I backed it down so I could turn around, BIG mistake. IT also was about 1 hr before dark & I could see myself spending the night out in the swamps Ha. I finally mamage to turn around & get out but then the motor alarm went off & I had to shut it down. I'm luckey someone came by just at dark time. Thanks again for the help.<br />Karl

 

[Dhadley]

Re: Water pressure

If the hot horn went off -- change the head gaskets! And use good ones like OE or Aqua Power. Glad you didn't have to spend the night in the swamp. Good luck!