In my quest to reinvent the wheel and after reading so many negative comments on a variety of fluid extraction units, I designed my own.
Using PVC pipe, caps and some brass fittings this is what I came up with...
I used and inexpensive 2.5 CFM vacuum pump from Harbor Freight which you can find for around $85.00. I already had the pump which I use for other things but it was this that started the gears turning.
I used 1/4" tubing and 1/4" barbed MIP (All 1/4 NPT threads) for the vacuum and extraction lines. I drilled and tapped with a 7/16" drill bit and a 1/4 NPT tap.
I added a 1/4" FIP barbed fitting to connect to the factory drain hose on my Malibu as seen below...
On the top I have a 3/4" ball valve for draining the tank with a brass hose cap for cleanliness more that anything. This sits on a 2" to 3/4" threaded PVC reducer and is connected to a 4" to 2" adapter.
The pipe is 4" PVC with a flat bottom cap.
The results were outstanding! I drained the engine in about 12 minutes with no mess and not a drop of oil anywhere...even when I drained the tank. Keep in mind the engine was cold and I was pulling though a 1/4" hose, up about 4 feet of elevation. I know the unit can move much more volume because I can shut off the vacuum pump and the residual vacuum in the tank will keep pulling oil for an extended period of time. This still far outperforms most store bought systems in the current configuration. Next I will be changing to a 3/8" i.d. barbed fitting, on the fluid side only, to match the factory hose and I will be adding a hydraulic quick connect so I can switch back to the 1/4" tube for the lawnmower, trimmer etc.
I suspect that if I had the hose running through the bottom of the hull with a 3/8" hose l, I could drain it in half the time or better. For comparison I also drained the transmission in about 60-90 seconds.
The best part is this unit is serviceable with parts available at any hardware store! No special fittings or connections and it can be adapted for many other engine or machinery as long as what you are extracting is compatible with the tank and hoses.