You're getting bleed -by somewhere. My guess is around the bleeder. Sometimes it can be hard to tell.

 

I believe the reservoir cap hoses can be reversed and will cause a lack of suction. I did this with mine and could not get any vacuum. Make sure you lubricate the reservoir seal with vaseline as per the instructions.

 

Put your finger over the end of the hose.
Try to pump up a vacuum, it you can't it would be a defective unit.

Larry

 

The MityVac tube connections are fine. You are pulling in air from outside the system through the bleeder screw threads. That is why you are losing vacuum. Just continually pump the MityVac and air bubbles and the old fluid will go throught the MityVac tube into the pump container. You are not letting air into your brake system this way so don't worry. Here is an excerpt from Bare's brake bleeding procedure. Constantly pumping the MityVac to bleed the brake line is still much faster than without it. If you wnat to bleed it super fast, remove the bleeder screw, wrap Teflon around the bleeder screw threads and re install. Beware though, this will empty your reserve very fast and if someone isn't pouring in new brake fluid into the reservoir as this is going on, your reservoir will empty quickly and suck air into your system and you will have to start over and use more fluid.

Vacuum bleeding
Keep in mind that with a vacuum bleeder sometimes it pulls so much vacuum that you get a little bit of air leakage around the threads of the bleeder screw. This leakage results in tiny air bubbles in the fluid during the bleeding process (they resemble foam). This is normal when using a vacuum bleeder and should not be taken as a sign of trapped air in the system. If you are concerned about this inhibiting your progress then you can remove the bleeder screw and wrap it with teflon tape (like you use on plumbing fittings). The teflon tape helps seal the threads and prevents these tiny bubbles from showing up during bleeding, you should note though that this is not mandatory to ensure a good bleed.

Finally, to read the entire write up for bleeding the brakes, click on this link and under maintenace, click on Bleeding the Brakes. http://www.bareasschoppers.com/

 

Hardway - Thanks. I connected everything up and left the bleeder valve closed. Pumped the Mity...and nothing. No vacuum was created and the gauge just bounces and returns to zero. Isn't the Mity designed to be able to build up a vacuum, then open the bleeded valve to get the fluid moving? The manual says to connect it, pump the handle and then open the bleed valve after a vacuum is created.

If not, what's the point of having a gauge? To check for leaks I pulled the hose off the Mity and sucked on it. I was able to create a very good vacuum and the hose almost sucked a piece of my lip off until I pulled it free. I reconnected the Mity, pumped the handle...and nothing...with or without the bleeder valve open.

There's got to be a better product out there. Appreciate your help.

 

Ok, you have an air leak somewhere. MityVacs are good products and work great. Remove the hose from the plastic stub directly opposite of the plunger and place your finger on the opening. Now pump the vac, this should give you a vacuum and the needle on the gauge will raise and stay when the pumping stops. The needle will drop when you remove your finger. If this doesn't happen, you have a leak somewhere in the pump itself. Take it back to the store and get another one. If you get vaccuum with your finger over the hole and the needle rises and stays, you have a leak in the hose or container cap that the hoses attach.

 

I thought about it. The MityVac is tested before packaging. I think I know the problem. You have to connect the smaller tube to the larger tube. The larger tube will not be tight enough around the bleeder head to create a vacuum. Connect the smaller tube to the larger tube and force the smaller tube on the bleeder head. Pump it up with the bleeder closed, vacuum will register on the gauge. Open the bleeder screw and pump. See the pic below for the connector that came with you MityVac (the red pen cap is pointing to it. This connects the smaller tube to the larger tube. Make sure your fluid container is affixed tightly to the container cap.

 

Did you check the relief valve on top of the mity vac. I was accidentally depressing it and it wouldn't form a vac. Not saying that you're doing it, but it may be stuck open.

 

Better yet, throw your mighty vac in the trash and buy speed bleeders instead. The only thing I use my mighty vac for now is to drain the reservoir before bleeding so I get clean fluid faster.

I hated the fact that it always pulled air past the threads and I could never tell if there really was air left or not. I'm never a fan of wrapping teflon tape on the threads, since it can tear and leave bits of teflon floating in your brake system. It's not a huge deal, everyone does it, but I just prefer not to. The speed bleeders work awesome, I'll never use a vacuum to bleed again. I bleed my clutch and brakes once a year minimum and it's a snap.

I agree your problem sounds much worse than threads though. Either it's not tight on the bleeder, as suggested, or you have a cracked hose or something.

 

I was at Sears the other day and there were 3 MityVacs there and all had been opened and put back on the shelf. Sort of scary that they might not be working as advertised even though this thread and others have glowing reviews of the item.

Wtih that thought in mind where would I find a "speed bleeder"? Sounds like it may be cheaper and possibly easier to use.

There is also a all metal unit at Sears, about $60, but it may be better.

Thoughts?

 

The MityVac I purchased is being returned for a refund. As far as I'm concerned, it's junk. I use a 12V electric pump oil extractor (Jabsco brand) to suck oil out of my inboard boat engines, and I'm going to try that next. I also ordered the speedbleeders for both the brakes and clutch. The hose from the oil extractor is a perfect internal fit for the flexible rubber hose I got from speedbleeders so I'll get a tight fit on the hoses and on the bleed valve. The oil extractor will suck about a quart a minute of hot 20W50 oil so I have to assume that it'll suck thin brake fluid very quickly and I'll probably have to crimp off the hose a bit to control the flow, or have someone controlling the pump on/off while I pour fresh fluid in the reservoirs.

Might just be easier to install the speedbleeders and just pump the levers until the fluid runs clean. I'm going to try both methods and I'll report back.

 

You might need the vacuum if you're starting with an empty system, but if all you're doing is bleeding, it'll be much easier to just pump the levers. You're making it harder than it needs to be by adding the vacuum pump and you'll likely draw air around the bleeder threads making it difficult to determine if you're completely bled.

If you're drawing fluid into an empty system, just add the hose to the bleeder screw, turn it on, and crack the bleeder slowly. You can use the bleeder screw to regulate the amount of vacuum. Once you get a decent stream, stop, go to the next bleeder screw, do the same until you've done them all. Then, bleed using the levers only in the proper sequence.