Mityvac issue - PeachParts Mercedes-Benz Forum

cdplayer · #1 09-12-2008, 01:44 PM

I realize most of you DIY guys have this important tool in your arsenal.

So I got one too. I beleive it is the Silverline model. A new one. But it does not work. It's the metal type with the gauge on top and a rotating valve on the side just under the gauge to chose a pressure or vacuum function.
Comes with a plastic bottle for the brake bleeding function as well.

My problem is squeezing the handle to operate the pump gets me no results. I hear air pressure within the pump but do not feel vacuum at the attachment port or air pressure at the same port when I rotate the valve to "pressure". It's as if pressure is just passing back and forth within the chamber.

Am I doing something wrong? If this pump is faulty I just have to eat the loss.

Obviously the gauge registers zip with either function.
Attempting to operate right out of the box. Within the assessory bag, besides all the different port attachments, is the pressure port safety cap.
It is not attached to the pump at this time.

Stumped. Any help would be greatly appreciated.
Thanks in advance, Dan(cdplayer)

Brian Carlton · #2 09-12-2008, 01:48 PM

Connect a short piece of hose to the vacuum port. Place your thumb over the end of the hose to seal it.

Pump up the handle with your other hand and the gauge should respond.

You can't develop vacuum or pressure when you're open to the atmosphere.

cdplayer · #3 09-12-2008, 02:40 PM

Quote:

Originally Posted by Brian Carlton

Connect a short piece of hose to the vacuum port. Place your thumb over the end of the hose to seal it.

Pump up the handle with your other hand and the gauge should respond.

You can't develop vacuum or pressure when you're open to the atmosphere.

Thanks for the reply. I have made the connection as you described.
Should have been more clear in the description. Just frustrated.

With the hose attachment in place, there is no vacuum felt or registered on the gauge.
With the selection valve turned to "pressure", there is no pressure felt at the hose, and no pressure registering on the gauge.

I hear air passing back and forth it seems within the pump chamber. I have disassembled the pump to analyze. To no avail.
Leads me to think the pump is faulty.

Brian Carlton · #4 09-12-2008, 02:50 PM

Sounds like you have it covered. Pump must be faulty. Surprising........they are very reliable units.

Factory defect??

cdplayer · #5 09-12-2008, 03:15 PM

Possible factory defect. Hard to tell with everything looking new. I may attempt to accessing the valve inside the pump chamber. I think it operates as a check valve. This might be the cause. I have a bid on another cheaper version on Ebay now. Maybe between the two, I can get a good working one. Thanks for the help. Dan

Matt SD300 · #6 09-12-2008, 04:16 PM

Hey Dan,

Check out harborfrieght. There should be one close to you.......

http://www.harborfreight.com/cpi/ctaf/Category.taf?f=bylogo&logourl=mityvac%2Egif&brand=Mityvac

cdplayer · #7 09-12-2008, 05:24 PM

Thanks Matt. Long time no hear...

BoomInTheTrunk · #8 09-12-2008, 06:26 PM

mine does the same and i have taken it apart to see what might be wrong. Well I did not find out what was wrong with it. The diaphragm and everything seemed to be fine. I to am interested as to what might be wrong with it.

cdplayer · #9 09-12-2008, 10:44 PM

Quote:

Originally Posted by BoomInTheTrunk

mine does the same and i have taken it apart to see what might be wrong. Well I did not find out what was wrong with it. The diaphragm and everything seemed to be fine. I to am interested as to what might be wrong with it.

Well after totally dismantling the pump, I have come to the conclusion this device was not assembled properly. Almost all the parts are there. But two places where a "good" seal should be lacks any gasket.

The model is Silverline 4555.

I shaved off a tiny ring of rubber from a normal Mercedes vacuum hose. Then I fitted it to the elbow port that is secured by two screws on top of the pump. I reassembled thinking all is good. Wrong! I did get pressure. So I am 1/2 way there.

When I rotated the select knob to vacuum, same internal air sound. But no vac. Rotating select knob back to pressure. I have pressure.

Too much time wasted today. Boxed everything up. Will attemp further later.

OMEGAMAN · #10 09-13-2008, 12:13 PM

Squirt a small amount of oil in the vac port and try it again. Had to do that with mine and it works fine now.

cdplayer · #11 09-14-2008, 12:34 AM

Quote:

Originally Posted by OMEGAMAN

Squirt a small amount of oil in the vac port and try it again. Had to do that with mine and it works fine now.

Thanks for the tip. I thought of that too. But no help. The upper elbow chamber just doesn't seem to be making a good seal.

kmaysob · #12 09-14-2008, 01:46 AM

if you just bought it, why not take it back???

cdplayer · #13 09-14-2008, 06:54 PM

Quote:

Originally Posted by kmaysob

if you just bought it, why not take it back???

Got it at a liqidator. An as is purchase. I am wanting to know for myself WHY it does not work.

raslaje · #14 09-14-2008, 10:59 PM

Amazon has a maintenance kit for the Mityvac
http://www.amazon.com/Mityvac-4100-Silverline-Maintenance-Kit/dp/B000OQHRZ6

Dee8go · #15 09-15-2008, 09:32 AM

I have the eight liter (or maybe it's eight quart) model. I have not actually used it yet, but put the pieces together and it appears to create a vacuum as it is supposed to. Hopefully, this week I'll change the oil in Max with it.