The home made manometer is a loop of tubing if you put a valve at the bottom of the loop you can slowly open it if balance is off far enough to suck fluid into the engine you can close it before that happens to prevent it.They tell you to use other fluid but I use 2 cycle oil because if it does get sucked in it won't hurt anything.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!