I have a story related to the puzzler where the vacuum cleaner draws suction on the crankcase through the oil fill opening so that the drain plug can be removed without the oil coming out.
I did this a few years ago after the threads on my car’s oil drain pan got damaged from over tightening the drain plug.
I wanted to try various things like a new drain plug with various washers to try to stop the leak.
The vacuum leaner idea worked very well, and after the plug was removed, no oil came out. I tried it many times to try various plug/washer combinations. (Eventually I had the pan replaced rather than try an oversized plug, since it never completely stopped leaking.)
There was uncertainty about whether the partial vacuum completely holds in the oil once the plug is removed. My experience confirms that it can keep it in well.
I’ll have you know I’ve made this exact mistake. I quickly pulled the plug, and stick my finger on the hole. While holding one finger on the hole, I put the gasket on the plug. Then I quickly put it back in the hole and retightened. It took less than a pint to top it back off, and I didn’t risk blowing up the neighborhood
I recall they mentioned that possibility. The suction hose doesn’t really have to have a tight seal on the oil fill opening. That dilutes any combustible hydrocarbons a lot. Also, most engines don’t suffer much blow-by at all, especially mine.
I’ve done the same thing @SpecialEd, somewhat messy, true, but didn’t lose much oil to speak of with the finger in the hole “quick-change” technique you describe.
When I heard the puzzler, that wasn’t what I was thinking the guy was doing. I thought he had dropped some small but critical part into the recesses of the engine, couldn’t find it, and was using the vacuum to try to retrieve it.
I’ve used a shop vac for this purpose, not just for cars but for finding any small part you’ve dropped and can’t find – and it really works well. Just put a nylon sock over the end of the vacuum hose, hold it on w/a rubber band. Then turn the vacuum on, and vacuum up everywhere you think the small part might have bounced to. It won’t go into the vacuum, everything will stick on the nylon sock surface, held there by the force of the shop-vac vacuum. Then you can simply sort through everything stuck there on the sock to find the part you are looking for.
This really came in handy one time when I was repairing my mechanical cuckoo clock. You know, the kind where you have to pull up the weights every day to make it go. The mechanism’s clutch (the part that allows you to change the time manually by just turning the minute hand) is held on with a tiny pin-like thing, like what you’d have if you cut the very tip 1/4 inch from one of those pins that come-with when you buy a dress shirt. To meet it’s purpose, it’s made of stainless steel and of a very stiff, springy type of steel. I dropped that thing, and I could hear it bounce around, seemingly all around the room after it dropped. But I couldn’t find that tiny thing no matter how hard I looked, even after 30 or 40 minutes of looking. So I got the shop vac out, with the afore-mentioned nylon sock, vacuumed here and there, and had found that tiny steel pin within 5 minutes.
I have done the same thing to a 150 gallon hydraulic unit reservoir.
It was shipped with a drain plug, but no ball valve to shut off the flow if you were just taking an oil sample or draining water from the tank.
Shoving a shop vac hose into the oil filler and turning it on will give you about 3, vital, no mess seconds after fully unscrewing the plug to yank it out of the way and put a valve with a pipe nipple back in its place.
If people don’t believe it, you can win money doing this.
