Differential Diagnosis for Vacuum Leaks

I just posted it in another thread, but thought is should have its own thread, because its a common problem.
Pump Seal Problems

First just use the pump all by itself, no tubing. Just place your finger over the nozzle and create a vacuum. If the pump is fine, it should go up instantly, and stay at that level with no leakage. With your finger in place, and the vacuum rock solid, use the air release valve a few times and see if vacuum drops when you press it and holds when you release it.

If this is good, put your pump aside, it is good and release valve is working.

If it doesn’t hold the vacuum, there is a problem with your pump. I had some vacuum leakage when I got water in my pump, so I took it apart and added some Vaseline to the lubricated areas, and it sealed it. I think white lithium grease would be better, but Vaseline will do it.

If you pump is good, then lets move on to your hose. Take the hose off of the cylinder and attach the proper end to the pump and leave the other end off the cylinder. Again, place your finger over the open end and pull a vacuum. If it is leaking, it is in the hose or fitting. Its really doubtful the hose is leaking, but you can be sure by removing the fitting and retest. If it tests good, its the fitting. If it leaks without the male fitting, its the hose (doubtful)

If its a male fitting, I really doubt it will leak, so it you have a leak in this combination of male fitting and hose, just pull it out of the hose add a dab of Vaseline, refit it and that should cure it.

If there is no leak in this hose and male fitting, then it is in the cylinder and female fitting section OR it is in the male to female coupling.

If the pump and male fitting hose combination are good, I suggest the following.

Go to the cylinder and gently unscrew the female coupling from it. Take a dab of Vaseline and lube the threads of the female coupling and re-install it. I recommend tightening by hand, if you use a pair of pliers…be very, very careful not to over-tighten and strip the threads. It only needs to be snug, so if you have strong hands, just use your fingers to tighten it. By the way, most have a rubber O ring between it and the cylinder to help seal it, check to make sure you have one.

Now test it by hooking it up to hose and pump. IF it STILL is leaking there is only one possible place it could be leaking…that’s at the male-female connection.

Make sure the male fitting has its black rubber O-ring on it, and put a dab of Vaseline on it and re-try it in the female connection and pull a vacuum.

When you test the cylinder for vacuum, place it on a clean flat surface of your body that you know for sure you can seal it, like your palm or thigh or any surface of your body that is relatively flat and minimal hair.

If its still leaking after that, and there is no obvious crack in the cylinder…then I throw up my hands and abandon you to your fate.

Thanks, I had read your advice before and tried it but I was afraid to put too much Vaseline in the pump. I opened it back up and coated it pretty good. It works now.

I second the lube up the threads fix. Worked great for me. Thanks sparky.

Yes sir go crazy with the lube and you will be able to maintain an exact pressure for longer no question. Also make sure your pubic hair is not getting in the way of the seal, shave as much of your hair off as you can. Skin to tube is way better than hair to tube. Last make sure you have the right size tube, this is very important.

Has any one tried soap water around the connections to see bubbles? I know it works for gas connections.

Soap water around the connections works with gas connections because that would detect positive pressure. The gas movement is toward the outside.

With pumping, we are creating a relative vacuum, so any liquid or soap bubbles would be drawn in, not out. So, I’m not sure the same detection method would work here.

Shave if you want, but close trimming in the immediate vicinity of where the cylinder meets the skin generally works, also.

Would ordering a sleeve fix this problem?I was going to order one if so. Vets please respond. Thanks in advance!

“This problem”? Which one? There are a variety of problems with a variety of causes, and a variety of solutions. Which one are you having that you hope to solve by ordering a sleeve? And have you worked through the differential diagnosis in post #1 in this thread?

Yes, soapy water does work. Bubbles form at vacuum leaks similar to pressure leaks.

Sleeves are not needed for professional type cylinders. By professional I mean any by the major distributors like lapdist, boston pump, vacutech, etc.

I guess I wasn’t doubting that so much as whether you would be able to see them, depending on where the leak was.

It wouldn’t hurt anything.

I trim my pubes really neat anyway, but I still need a really thick coating of Vaseline on the base of the tube and over my pubes or I get leaks, I don’t know how guys who don’t trim can keep a vacuum even with Vaseline!

So I just bought this harbor freight pump and it cant hold a vacuum. I was going to return it since it didn’t work from the get go, but if it is just a simple fix I would be willing to do it. Anyways, how the hell do you get this thing apart to lube it up!??!

Also how would lube be the thing that’s causing the leakage?

Edit: Nvm, I see the thread you posted.. ill read that now :)

Great thread. Very useful, I thought I had a leak.

Thanks for making this thread. I’ve been pumping for two weeks with no issues then suddenly, the pump/cylinder couldn’t hold a vacuum. All I needed was some vaseline on the female connector and everything works again.