Want to test the brake booster check valve/vacuum leaks on my 1986 v6 SE.
What is a typical vacuum reading if I disconnect the hose that is attached to it?
Also suspect trhe brake booster as it is original. I am interested in doing the booster upgrade.

Replace thew check valve on booster if in doubt. Only a few bucks. For further testing... go here....


Replace thew https://m.roadkillcustoms.c...power-brake-booster/

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

If you disconnect the booster tube at the upper manifold and cover the hole, the idle speed should be the same as when connected. If it does go down, you have a leak in the booster assembly or the tube.

Thanks guys, will do.

See my Cave, Vac Leaks

booster and line sees Manifold vac at idle.
Booster CV "closes" to keep Vac in the booster when you mash to gas or engine is off.

Start car for 1-2 minute.
Shut off and wait a 3-5 minutes minimum. Go for coffee etc.
Then Push brake pedal. should have enough vac reserve to run brakes normally 2 or 3 times becoming harder and harder to push each time. To the point pushed w/ both feet barely moves.

If that works then CV and booster itself isn't your problem. Hoses and hard line to them maybe.

Most vac leaks are somewhere in the engine bay.
Many booster problems are same plus 84-86 w/ booster filters that plugs up there.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Used Rodney's brake rod kit and installed the Summit brake booster.
What a difference! Much better boosted feel and braking.
Only hard part was getting off and on the 4 nuts that hold brake booster bracket on with my fat hands and short fingers.
Pounding the clearance was fun, holy crap they made these cars out of some strong steel. I am used to working on MG's.
Now my parking brake doesn't seem to adjust rear brakes much, always something, they are not low, just wanted to see if I could get them to come up a little.