Vacuum oil change

Several months ago, I saw a thread where someone asked for ideas of what to do with their vacuum pump.

greasyfingers01 was thinking of hooking it up to a propane tank, and using it as a vacuum oil extractor to do top-side oil changes. Well, that lit up a light bulb over my head, and I remembered that I have a junk forklift propane tank that has a liquid level gauge (so I'll know when to empty it), and I started screwing things together.

Right now, it's hanging under a corner of my garage door that's pretty unusable space otherwise:



The most expensive parts for me were the three ball valves. Most everything else I already had as spare parts.

I removed the safety valve from the top and the vapor fitting, and found them to conveniently be 3/4 NPT. Into the top hole I teed in the vacuum/pressure gauge I conveniently happened to have.

To the the left, is a pressure regulator (mainly to keep me from destroying the gauge), set to allow me to hook up an air hose and pressurize the tank to 20PSI (so i can drain it using the liquid valve, opposite the vapor fitting, that came with the tank).

To the right, is a venturi vacuum pump (the guts of one of the $12 ones from HF designed to be used for car AC evacuation). It pulled the tank down to 29" within about 2 minutes. It was still past 28" a few hours later, so I think I'm more than well enough sealed up.



The door clears it with a couple of inches to spare (action photo of it while being vacuumed down the first time in position).

I've got 25' of 3/8" polyethylene tubing stuck into the "vapor" connection (enough to reach a car in front of either garage door, or even up into the loft to change the oil in my compressor), and on the end of that, a plastic shark-bite adapter and 4' of 1/4" ice-maker tubing (I'd never use it for that purpose, but it has its uses) that fits perfectly into my dip-stick hole. I think I may add another valve near that end of the 3/8 tubing.

The o-ring in the liquid out valve seems to seal well around a piece of 5/8" clear vinyl hose, so I can use that to neatly empty this thing back into quart bottles if I chose. I cut it so the hoses can be bent around and be left facing up, so there's no drips when done.

I just did my first oil change with it yesterday, and awesome doesn't even begin to describe it! I've already got a long list of things that this will really help with (like @$%^&@$% Honda motors that otherwise need to be tipped over to get the oil out).

The only catch I found, is that the dip-stick enters my Outback's pan at an angle, and it is easy to shove in too much tubing so that it curls up in the pan and isn't on the very bottom. It sucked oil well for a few minutes, then sucked air. I had to play around with it a few times to find the sweet spot.

Maybe next oil change, I'll mark the tubing for where the sweet spot is on each vehicle (color coded perhaps?).

Thank you greasyfingers01 for the inspiration!

You could get one of those sweat in adapters with that acme thread that will hook up the Auto AC vacuums pump yellow lines. I got a pack of 5 or 4 for like $10 at local HVAC place for the same project, just never find the "tank" for it.

something like this but I have to look into the pile of never completed project parts to be sure.

https://www.grainger.com/product/JB-INDUSTRIES-Access-Valve-20W298?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/3X728_AS01?$smthumb$

That would work for this purpose. The HF venturi block had 1/8 NPT holes, so it was easy enough to plumb in. And should there be any flammable vapors involved, the risk when using a venturi vacuum pump is much lower than with using a conventional vacuum pump (plus I wouldn't want to use my good vacuum pump for this work). Anyway, I already happen to have a compressor that's more than up to the task.

edit: come to think of it, I pulled that acme threaded adapter off the vacuum pump to begin with, so now I've got one of those with a 1/8" NPT adapter.

Nice job on the build.

Now, I have to ask. Why a vacuum top side oil change? Part of an oil change is to inspect the vehicle. While it's in the air / your under it. Take time and look around.

Now if you would have said a vacuum brake bleeder. I would be, All In!

Capt. Chrysler

Multiple reasons.

1) The ancient concrete in my driveway is so pebbly that it's tough on the knees. Yeah, I've got pads to make it more comfortable, but if I can avoid one time crawling under the vehicle (to replace the drain plug), I'll look around just as much, but be happier at the end.

2) I don't have a lift. Getting a vehicle "in the air" isn't always so easy (and rolling around my jack on that concrete at the hours of the night that I have available to do those oil changes makes a noise I'm not thrilled with)

3) The oil filter on the 2013 Outback is mounted standing up, in a cup. It'll spill a few spoonfuls of oil into the cup when I unscrew it. Using the vacuum, I put the tube in a dimple at the low point of the cup, and all the oil gets sucked right up. I can then stick the suction tube into both holes under the filter and remove even more oil that would never be removed during a drain change. It's like it was engineered specifically for a top-side oil change.

4) A more complete oil change. Because a drain plug is never in the lowest point in the pan (or else it would stick out in a way that leaves it vulnerable to damage), you can actually remove more old oil from above than from below (noting the warning I mentioned about being sure you got the tip at the right spot).

5) Not every engine I change the oil in has a drain plug, or a reason to look under it. My Honda EU1000 generator for example needs to be tipped on its side, which is messy enough, but my Honda HRX mower is no fun at all to hold sideways over a drain pan. My Miller welder/generator has a drain plug, but with a 600+lb machine sitting a level lower than the height of my normal drain pan, I've got to hunt around for a shallow pan, and empty it several times with each oil change. And there isn't anything to see under that machine anyway.

6) It doesn't have to be used just for motor oil. The rear differential in my Wrangler TJ has a rubber fill plug, but no drain plug. The usual procedure is to remove the cover, clean it until immaculate, make a new gasket using RTV and bolt the cover back on. With this, I can get to the bottom, **** the gear oil out, and use a piston baster to shoot new oil back in, with no worries about a leaking seal.

As for vacuum brake bleeding, yeah I could use it for that too. I already have a MityVac that I use for this. I use that with a cup that holds a little brake fluid (so you don't shoot fluid through the pump). Since waste brake fluid gets mixed with waste oil for recycling anyway, I see no reason I couldn't put a vacuum fitting adapter directly on the hose and use this for brake flushes too. I still use the pedal (I'd love a Motive pressure bleeder though) for the final bleed, but to get fresh fluid into the lines, the vacuum bleed is a great time saver. And even if I do a 2-man bleed with the pedal, I could have the hose on the bleeder, so there's no dripping.

I'd just have to keep a closer eye on making sure I don't **** the master reservoir dry (the collection cup holds less fluid than the master, so with the MityVac each time I empty the cup, I refill the master).

Rlitman: Very clever! It's a great idea; particularly for modern differentials that don't seem to be outfitted with drain plugs.

RM209

Thanks for sharing your build,
I experimented years ago with a Vacuum pump that was not up to par for its intended purpose, trying a 5 gallon plastic bucket it worked great till it was about 1/4 full then crushed it in a blink of the eye.
Bought a Harbor freight unit for a crazy large fleet, used it a lot, wish I had one for the wife's lawn mower, was a shock not finding a drain plug! actually read the manual after that one.

I'm building one but using an old air operated hand vacuum and pvc for the tank. Changing the oil in the mercedes can be a chore since I gotta remove the bottom belly pan. Plus that's how my dealer did it. The filter is on top as well. The dealer used a vacuum pump similar to a bike pump only larger.

Sent from my SM-N910V using Tapatalk

man I need to build me one of those. not for cars, but like you said, mowers and differentials, trannys, that kind of thing. also would work well for my boat. sick of draining the oil into the bilge and letting it drain out the back...super super messy and not so good for the lake...(got the Volvo penta car motor in a bayliner I/O)

Followup:

Man, a forklift tank holds a lot of waste oil. Three vehicles on the road, plus several brake flushes, and I only now FINALLY had to empty this beast for the first time.

I didn't trust the o-ring on the liquid out hose to keep the hose from blowing out, so I unscrewed that acme adapter from the valve and found a 1/2 MPT underneath. Yay! That let me stick a hose barb on the valve. I also put a 12" stick of schedule 80 PVC onto the far end of the drain hose (with another barb), so the hose stays put in my disposal containers, and it makes it easier to hang the hose without dripping (plus it accepts a PVC cap to keep dirt out).

Originally, I had a plastic sharkbite type valve at the far end of the 3/8 PE extraction tubing, so I could shut the vacuum off remotely, but that valve failed on me. It seems that something in the plastic valves couldn't stand up to the oil (even though that 1/4 to 3/8 adapter has held up fine). I've replaced it with a 3/8" brass PEX valve that I clamped in place. The remote valve really helps with brake bleeding, where I can hook it up under the rear axle and turn it on from there when I need it.