Hissing from brake booster

[AirSpeed]

I just noticed a hissing noise coming from my beak booster. I can hear the sound change if I hold my finger at the bottom of the master cylinder where it meets the booster can. Do I need a new booster?

[hamjet]

I mentioned in your other post it might be a vacuum leak. This may be it. disconnect and plug where it goes to the manifold and see if that solves the rough running problem. did you get it running long enough to get the cam broken in yet?

[Andy4639]

You need to take the master a part and see if the seal is in it are has blown out. If it is leaking then as stated it could be a bad one and could be giving u a fit on idling also.

[AirSpeed]

Originally Posted by hamjet

I mentioned in your other post it might be a vacuum leak. This may be it. disconnect and plug where it goes to the manifold and see if that solves the rough running problem. did you get it running long enough to get the cam broken in yet?

I had the vac line to the booster plugged, hadn't hooked it to the booster till later. I did get the cam broken in, in the paperwork it recommended running it at 2000 rpm for 30 minutes. All went great, oil pressure great and ran nice and cool. Once the cam was broken in it ran way better, don't know why but it's pretty smooth. Didn't see any smoke out the exhaust, it runs nice now.
I took it for a drive and tried to stop, no power brakes and one of the return springs on the carb fell off the same time, it was terrifying! I couldn't stop so I shut it off and used the park brake just in time not to run into the napa store! I haven't got on it yet but I can already feel a lot more power than my old engine, it sounds nice too, just a little cam action, not to much. Can't wait to get the engine totally broke in so I can floor it!

[davepl]

Originally Posted by AirSpeed

I just noticed a hissing noise coming from my beak booster.

Maybe one of your nostrils is clogged?

I'm really only posting to say do not try to take the booster apart. It can be done with a press and fixture and knowledge, but the first time I tried it one half took off across the garage and smashed a dent into my '69 Camaro two stalls away. Which was way better than hitting me, so I wasn't too mad.

In other words, they're unless a massive amount of counterspring pressure inside.

[AirSpeed]

Originally Posted by davepl

Maybe one of your nostrils is clogged?

I'm really only posting to say do not try to take the booster apart. It can be done with a press and fixture and knowledge, but the first time I tried it one half took off across the garage and smashed a dent into my '69 Camaro two stalls away. Which was way better than hitting me, so I wasn't too mad.

In other words, they're unless a massive amount of counterspring pressure inside.

Thanks for the warning! I wouldn't try to fix something like that, I'm just going to get a new one, only $71 at NAPA.

[Andy4639]

Take the master loose from the booster is nothing to worry about. It's where the rod comes through to push the master cylinder rod so the fluid can flow. Check it and see if the seal is bad. With vehicle off and bleed the booster down by unplugging the vacuum source to it. Then take the nuts loose and pull it a part and see if the seal is in deed come a part. A new seal is maybe 2 are 3 dollars!

[AirSpeed]

Originally Posted by Andy4639

Take the master loose from the booster is nothing to worry about. It's where the rod comes through to push the master cylinder rod so the fluid can flow. Check it and see if the seal is bad. With vehicle off and bleed the booster down by unplugging the vacuum source to it. Then take the nuts loose and pull it a part and see if the seal is in deed come a part. A new seal is maybe 2 are 3 dollars!

Thanks! I'll check it out tomorrow. Wouldn't mind saving a few bucks! Been an expensive month! New tires, new engine, I could use a brake! (Get it, brake! I know, I'm hilarious!)

[AirSpeed]

I've decided to just replace my brake booster, don't want to mess around. Went to my local NAPA store and they show two boosters for my truck, neither is in stock so I don't want to have them order the wrong one. My truck is a 72 gmc k1500, do any of you know the part number? Thanks!

[AirSpeed]

My new vac booster will be here in the am, I'm wondering if I can switch boosters without messing with the brake lines, it looks like a simple job but I've never pulled a booster before. Are there any special steps required or is it a simple switch?

[leddzepp]

Pretty simple. Just need to bend the lines a bit and pop it off.

[AirSpeed]

Well I installed my new brake booster a while back but it didn't help much, ended up adding a vacuum canister and it made a big difference, almost acceptable but I still think I'm going to get a vacuum pump. Looked at some on Summit and Jegs but they want $250! I'm sure I need a high volume pump but $250 seems crazy. I already have the vacuum tank so I just need a vacuum pump. Any of you found a sub $100 vacuum pump that will work?

[engineer_gregh]

What cam are you running?