Where can I hook up water pressure gauge

[nimmor]

I have a 1959 35 H.P. Johnson and am trying to install a pressure gauge for the water. I drilled and tapped the top of the thermostat housing and put a fitting in. Then ran copper tubeing to the outside of the outboard then ran flexible tubeing to the gauge on my dash. I have a lot of water coming out of the thermostat hole with the housing removed but with it installed I was not getting any reading on the gauge. I disconnected the copper tubeing and stuck the garden hose to it and the gauge went up. Then I started the outboard but no water was coming out of the fitting. I guess this is not a good place for it. Does anybody have an ideal of a good place to install the fitting so I can get a water pressure reading? I have looked and do not see any exsisting holes to install a fitting to access water.

 

[CATransplant]

Re: Where can I hook up water pressure gauge

If you tapped into the thermostat housing, you'll get no flow until the thermostat opens. If you wait, you should get some reading. I don't have any idea what the water pressure is in the old Big Twin. It's not going to be really high, I'm sure.<br /><br />Are you doing this just to make sure the motor is pumping water? I have a 1959 Johnson 35hp, and I know it's pumping water because the water comes out the idle relief hole on the back of the midsection. I'm planning to put in a new impeller every other year. Beyond that, I'm not concerned. I check the idle relief every time I start the motor. If there's water there, no worries.

 

[CATransplant]

Re: Where can I hook up water pressure gauge

Belay that. My 35 is a 1958. Same motor, though.

 

[nimmor]

Re: Where can I hook up water pressure gauge

I am doing this because I don't get much more than a fine mist out of the relief port which I was told is normal on this old of a motor. But water is circulating because I can take the thermostat housing off and start it and water gushes out. As for the thermostat opening I gave it about two minutes and still had no indication on the gauge. I right away took the housing off, and yes it was hot, and the thermostat was opened. I even tried it without the thermostat in and still nothing. I am thinking maybe this was a bad place for the fiiting. I drilled into the little tiny hump on top of the housing and maybe not enough water pressure reaches there to go into the tiny hole of the fitting. Oh almost forgot, I did put a new impellor in last year, but it only has been run a few times and never out of water. When here at the house I have a garbage can I run it in. But even at the river I only get a fine mist.

 

[Paul Moir]

Re: Where can I hook up water pressure gauge

Speaking purely theoretically here since I've never tested it, I'm not sure what kind of pressure you should be expecting at idle. I mean, with the recirulating system I would be suprised by more than a PSI or two. It may be far less than that even.

 

[Chris1956]

Re: Where can I hook up water pressure gauge

RANimmo, You may be better off with a water temp gauge on that motor. There was a specification to check the operation of the thermostat by sticking a meat thermometer up the exhaust port on the mid section. Also, my 1961 35 HP Evinrude came with a OEM temp light.