PC-85-928S

are there any post describing how to use a mighty-vac to test vacuum lines?
I tried searching, but I think there are many spelling variations, so I am not finding anything.

I was thinking about buying this one:

http://www.harborfreight.com/mityvac...ump-39522.html

but I was wondering if this would work, and what the difference was.

http://www.harborfreight.com/fuel-pu...ter-93547.html

Why do you pump it?

Do you do it with or without the car running?

danglerb

Car not running, disconnect at the vacuum source, usually the throttle body, hook up sucker, suck, watch the gauge. If the vacuum never gets very high, its a bad leak. If the vacuum doesn't hold its a small leak. If the actuator the vacuum line is connected to doesn't do what its supposed to, its broken.

Plastic version melted first time I left it in the hatch area parked outside. Not melted to a puddle, but warped and no longer working, and not warrantied.

I bought the cheap metal HF, but haven't needed to use it again.

Leon Speed

Get the mity vac in the first pic, it is excellent to test vacuum lines, vacuum actuators, to bleed brakes, etc. The second one is just a gauge, you will need something else to create a vacuum.

Leon Speed

Edit: the mity vac looks like it's made of plastic. Better get the one made out of metal.

For testing the vac lines, look here under "HVAC": http://members.rennlist.com/pirtle/svc.html

danglerb

This is the one I bought, on sale for $20 and used a 20% off coupon.
http://www.harborfreight.com/brake-b...kit-92474.html

Eplebnista

If you feel the need to have metal, I beat the crap out of one of these for about ten years:

When it finally died, I got the plastic mityvac. I have no issues with the plastic, but have only had it for a year.

dcrasta

Metal with built in gauge. Can use for many things. Combined with the cup you can use as a power-bleed.

It's basically a vacuum source, strong than you can generate by sucking on a vacuum line.

17prospective buyer

You could test non-ported (idle) vacuum lines simply with a vacuum gauge. A normal reading at idle for a healthy stock engine would be between 20-25 in/Hg for a non-ported vacuum source, if it is lower you may have a vacuum leak, but remember that a simple vacuum gauge can tell you alot about an engine's condition as well (carbon build up, sticking lifter, poor sealing, plugged up catalytic converter causing excessive backpressure). In fact, assuming all vacuum lines/sources are sealed properly, you can use a vacuum gauge to pinpoint almost every engine maladie that is related to the mechanical parts of an engine.

PC-85-928S

so hypothetically if I wanted to test my auto transmission vacuum line on the center rear of the engine, I would unplug it from the 7 way splitter, plug the line going to the transmission into the mighty vac, pump it up, looking for the gauge to hold a certain amount of vacuum, w/o leaking?

Leon Speed

yup

PC-85-928S

Do you apply the vacuum or the suction from a certain end? For example pulling or sucking towards the throttle body?

dr bob

Yes. You are testing both the line and the vacuum modulator that way. If you find that you can't hold vacuum when testing from the engine end, go ahead and connect the Mity-Vc to the modulator and see if that's what's leaking. If not, then it's the line in between.

On the device selection-- I had a Genuine Plastic Mity-Vac for years, maybe 20, before it gave out. Body is PVC so there's NO TOLERANCE for anything aromatic. Like gasoline in a leaking fuel damper you might be testing. Replacement is a Sears Craftsman that is amazing identical to the metal Harbor Freight tool, including all the accessories. Of course, the H-F unit costs a lot less, but it doesn't ome with the impressive Craftsman decal on the side of the barrel either. Knowing that, I should have gone for the H-F tool.

martinss

You'll also want to cap off certain lines, e.g. if you are testing the solenoid console as shown by Dwayne. I found that #8 screw protectors from Home Depot work well.

BTW, I bought the Harbor Freight (Princess Auto in Canada) metal one. Works very well.

h011yw00d

You guys are awesome. I had to buy my MitiVac, have it sit on the shelf taunting my for a few months and then read the instructions to get it to work.

Once I did I fixed my always-hot air misrouted vacuum lines and cruise control issues in a week. Made me feel like an a-number-1 pu$$y.

Shoulda' asked you guys how to make the damn scary thing work

PC-85-928S

came to $19.99 with 20% off coupon and free screw driver kit-can't get hurt!