When you make your U-Tube for balancing the carburetors you will find that even a slight difference in pressure can cause the fluid to be sucked out, hence the reason for using catch bottles. These are not necessary if the U-Tube has some sort of dampening to remove pressure fluctuations so you get a smooth fluid movement and a nice steady reading. I took a couple of 6mm plastic BBs from a toy gun and drilled a 1mm hole through them. Threaded onto a fine screwdriver.......
Wet the BBs with a little WD40 and shoved it up the plastic........
repeat for both sides of the gauge and hey presto..........
success!
The screwdriver keeps the hole in the correct orientation and the gauge works perfectly with a very stable fluid level reading. You can use any thing with a fine hole in it, not just plastic BBs, but the downside is the dampener makes it difficult to drain the fluid from the U-Tube for storage. Why drain it? Some fluids will make the PVC plastic go white with time and then you lose visibility of the fluid level e.g. Dot 4 brake fluid. A light oil should work well. I plan to use methylated spirits next time because it will be easy to drain out.
I am sure someone will be able to comment if auto transmission fluid affects the PVC clarity.
With dampening the movement of the fluid is slowed dramatically so there is no pressure on you to act quickly to prevent the liquid being sucked into the catch bottles or engine. The fine hole in the dampener also dramatically slows the passage of any fluid. Below is my quick build with a homemade U-bend (If you have a U-bend it makes life so much easier):
There are loads of comments about U-Tubes on this Forum - Have fun!
