[JohnWR]

And here you go!
Amazon.com: Rigid Plastic Sight Closed Circuit Liquid Level Gauge, Mounting Centers (In.) 5 : Industrial & Scientific

Max operating temperature of 225F is a little worrying.

 

[JohnWR]

Agreed, I'm having a problem visualizing how this is mounted.


Rob, can you explain how this would be mounted? I'm having a problem visualizing how this is installed.

Those are typically mounted by drilling and tapping two holes in the vessel, one above the desired level, the other blow it, that match the size and spacing of the gauge. The bottom one lets the fluid in and the top one lets air out. On critical applications there will be petcocks built into the top and bottom fittings to isolate the gauge when readings are not needed, or to allow the system to function with a broken gauge tube.

 

[JohnWR]

How does one get to the nut on the inside to tighten it down. One assumes the aluminum is too thin to just thread a male sight hole in as in the DDM example.

I think that you would likely have to drill the holes then weld threaded bungs over them for the mounting, and, as @rob the elder said, that specific gauge may not be correct for the application.

For boilers we use a sight gauge with petcocks for the primary level monitoring, and have a series of petcocks aligned vertically parallel to that gauge that can be cracked open to test for the liquid level.

 

[JohnWR]

Is the colourization due to age? While I've seen some that turned orangy brown, mine's still fairly whitish. Funny thing is I stumbled upon a BNIB GM unit at a liquidation warehouse for $20.
Is surge tank leakage a real problem for our cars? Looks pretty sturdy.
Perhaps the PAW unit's comes with a floating gauge like some european cars.

I have not heard of tank failures, so I suspect it is not a major issue. I suspect this is a case of "different is better" or at least "different is different".

 

[JohnWR]

Realistically you can do reasonably well without being able to check the level from outside, it is just less convenient because you have to open the cap first.

 

[JohnWR]

That response is like not needing a gas gauge. The Kappas have a low fuel warning light. If you really want to know, you can put a dip stick down the filler neck.

Not exactly. I have gone for years without needing to add coolant, so unlike gasoline it is not quite a "consumable".

 

[JohnWR]

Why not ask Dave to make one side thicker? Then you can tap a hole wherever you decide you need it.