I am trying to get the brakes to work (hard pedal) and have been told to check the vacuum on the booster, have done that and broke the connector, but was able to plug the hole to check vacuum, the tester read between 15 and 20 at idle is this right? And what does this test indicate?
When engine is revved the vacuum goes higher, is this right?
How do I correct it if it is wrong?
Also read somewhere that to check to see if the booster is working, to pump the brakes when the engine is off hold down brakes and start engine, if the booster is working properly the brake pedal should move slightly, mine did not.... any help????
The connectors are very brittle and the vacuum line from the booster is almost impossible to remove any suggestions? Is this heat fitted?

Well I think I have figured that the piece I was referring to the vacuum line to the booster will need to be replaced now, since the connector broke, ssshhheeesh everything I touch breaks!

That test lets you know if the vacuum pump is doing it's job, closer to 20 is good. I think the higher the revs, the higher the vacuum.
You may be able to rig up the mity-vac to the booster itself via the main line, take it off and hook up there, pump away, see if the booster holds vacuum.
Your car is 25 years old, some items will be brittle.

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83 SD

84 CD

Replaced the booster hose, did not break anything!!! Booster side reads 17-18. Vacuum pump side reads 17-18.

How are you telling the difference? 17-18 still indicates either a weak vacuum pump or a vacuum leak that still needs attention.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

well I tested and retested everything and finally my dad looked at it and figured it out in 5 minutes... the booster is not holding vacuum and the vacuum pump is reading in the 20's (yea!) So looks like I will be replacing the booster...wish me luck!! Parts will be here tuesday 4/6 looks easy...looks and the real thing are alway 2 different things...will post results and picts if I can get any

Even for a novice like me this was not a real hard job...the only real difficulty was trying to get to the bolts inside under the dash off, you will need an extension for your ratchet otherwise you will have to take it somewhere like I did and have someone remove the bolts you cant see...there are 4 that hold the booster in place, disconnect the brake pedal and the booster should come loose....I disconnected the master cylinder and one hard brake line to move the master cylinder out of the way...and gently persuaded and wiggled the booster out, replaced the oring or seal or whatever you call it....on the master cylinder, came w/ booster....bolted it all back together, took it back to the mechanic and had them tighten up the hard to get at bolts....bled the line I took off and it works great now!!! Yippee brakes again! The yuck that came out of the line was disgusting will need to bleed the rest of the lines too...but at least they work much better now!!!
Now to fix the bowden cable I just broke But the car does not shift thru all gears before 30mph now! yea, it moves now!!! I get up to 3500-4000 rpm now before shifts....hard....I thought something really bad was wrong.......it was the bowden cable yea cheap part

you need to get your brake fluid flushed out real soon. that yuck is a mixture of brake fluid, water, rust and dirt. brake fluid attracts moisture, and that will rust out your brake lines and damage the calipers and master cylinder. this is very important. good job on replacing the booster. shows you can do it if your patient and careful.

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1984 300TD "MAX" 303K+ still going...
fast '70 Chevelle 200k+
home built Shovelhead chopper

Glad to hear you've solved one issue, a hard shift may be adjusted out via the vacuum modulator on the transmission.

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83 SD

84 CD

I had to remove the Brake Booster when I changed the Front Sway Bar Rubber Bushings.
What I found is that on US models on the upper left there is a Bracket with a hole in it that your Extension and Socket can go through. See pic.

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84 300D, 82 Volvo 244Gl Diesel

Thanks all for the words of encouragment, I am learning slowly how this thing works and a real novice at mechanics...but it is great to be able to fix something yourself

Diesel 911: I think my booster is different than yours, mine had 4 bolts on the firewall inside above the brake pedal, the top left one you cant even see, the others were not real hard to get to..just a muscle cramping position, to get to them

Well I was messing around today and broke the bowden cable, so I rigged up a piece of vac tubing split down the middle and attached to the bowden cable, to try to correct the shifts, drove, shortened, drove, shortened the tubing.......now the dag gone brakes are going to the floor more forum reading...looks like I need a brake master now???
I can keep up with the gassers, now it hauls butt!! Before messing w/ the bowden cable it was a slug, shifted thru all gears before 30mph...
I think it would be a good idea to be able to get it to stop too....thought I had that fixed....
How can I tell if my turbo is working?? I have cleaned out the banjo bolt and it was completly plugged 100%, did not seem to make much of a difference...some people say they can hear it kick in at about 2200rpm...I dont hear anything other than the motor>>????

Are you losing brake fluid? I imagine, you need to find the leak. If there is nothing obvious, it may be leaking into the booster, if so, you'll need a new M/C.
You'll need to clean out all the associated lines to the banjo bolts concerning the ALDA. Your switchover valve, located near the brake booster may be giving you problems, you can bypass that to see if the turbo will engage.
You should be able to faintly hear the turbo spooling up. These engines can be loud, you can remove the large "U" tube between the air cleaner housing and the turbo, and check to see if the turbo will spin. With the engine off, just try to spin the turbo blades.

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83 SD

84 CD

I tried to take off that "U" thing when I was "trying" to put in new mounts for the air cleaner and had a heck of a time so I just left it alone....will have to study it some more.....you know that old saying 10% rule
You only have to be 10% smarter than the thing you are working on
so I guess I am not going to let an old piece of plastic beat me
Right now the number one thing is to figure out why the brakes are not working right.
I have not gotten under the car yet...I hate those ramp things. Checked the wheels they are dry.
does not look like I am losing fluid in the m/c so its coming from somewhere.....will have to wait till tomorrow....
When I installed the booster there was an "O" ring I put it on the MC did I do it right? I am wondering if that was installed wrong
Oh well will have to wait for more daylight.

The red arrows point to a couple of clamps you need to loosen and work off.
When you remove the cover and filter, you'll see three 10mm nuts, they are connected to the item I circled, take 'em all off then you can remove the air cleaner housing and "U" tube as one piece.
If you didn't get the "o" ring on right, you wouldn't be able to hold vacuum, giving you a very hard pedal. The problem you describe points to a fluid loss, remove the M/C from the booster and look inside.
Your pedal goes very far down without doing much stopping, that tells me the fluid is being pumped somewhere.

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83 SD

84 CD

So I go to work this morning and the brakes are working fine???? What the heck??? Maybe air in the line??