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TOPIC: 73 Johnson 115 V4 Water Press Gauge Hook-Up ?

73 Johnson 115 V4 Water Press Gauge Hook-Up ? 13 years 11 months ago #4224

  • MarkS
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Need some help here, y'all. I'm trying to hook up a water pressure gauge on my Johnny V4, got the gauge installed in the dash and the line run back to the motor. Thought I had the answer to where to tap into the cooling system to get a good reading, now I'm not so sure.
The V4's have a water passage cover between the V on top, looks like a "cast in" place to install the fitting. Problem is the fitting will be too close to the flywheel! (We don't want a broken water line, now do we. :S ) I thought about going just forward of that and drilling and tapping a hole there, but don't think it will be thick enough to hold threads securely.
Now I'm leaning more toward drilling and tapping down around the cylinder head or head cover area to get away from the whirling destruction of the flywheel, but unsure about where to tap in. I was told the OMC gauge instructions (for later models) suggest cutting the cyl head drain hose and inserting a fitting (which would have to be fabricated) there, I just don't think there would be much pressure that far down the line.
Surely somebody has done this before, just gotta find 'em.

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Mark

Re: 73 Johnson 115 V4 Water Press Gauge Hook-Up ? 13 years 11 months ago #4227

Why would you think that there is not enuff pressure when splicing into that hose?
Time to look at a later schematic to see where to put this.
The location near the flywheel was never meant to be for a pressure tap.----There are numerous places on the water cover and cylinder heads where you can " tap into " the water jacket.

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Re:73 Johnson 115 V4 Water Press Gauge Hook-Up ? 13 years 11 months ago #4230

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I figured (quite possibly wrong again!) that the water coming down those hoses would be just draining into the exhaust, not under pressure. Those hoses look to be OE, so I'm going to order some new ones as preventative maintenance, could fab up a fitting on the new ones.

I wouldn't mind drilling and tapping a hole in the head or cover, just a little leary about getting it in the right spot. With my luck, I'll get the wrong spot and get into the combustion chamber! Maybe the hose WOULD be the way to go............ :unsure:

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Mark

Re:73 Johnson 115 V4 Water Press Gauge Hook-Up ? 13 years 11 months ago #4231

Those instructions have been printed for some 30 years and the saying is
" if all else fails read the insstructions "
enuff said.

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Re:73 Johnson 115 V4 Water Press Gauge Hook-Up ? 13 years 11 months ago #4602

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Well, I ordered two new hoses, and just thought better about cutting them up and having to fabricate some kind of adapter fitting to go into one of them. Also, the way they are curved, (which is why I didn't just use bulk hose), it would be tough to do. Soo, I drilled and tapped the housing (thermostat) where they meet and guess what. Getting no reading on the gauge. Now what?
Guess I'll take it to the lake and check it out right!!!
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Mark

Re:73 Johnson 115 V4 Water Press Gauge Hook-Up ? 13 years 11 months ago #4620

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Lake test on gauge = GOOD! Must have taken a few more minutes to get the pressure up the line to the gauge.

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Mark
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