Vacuum issues - help me gents
 

I've got a vacuum issue that really sucks (sorry i had to open with that line)

My rig is making a loud hissing noise that is only there when i don't step on the brakes. As soon as i brake even a little bit, it goes away. I popped the hood and its pretty loud but i cant seem to find it. Does this sound like maybe i broke a diaphram in my booster? It's driving me nuts.

Re: Vacuum issues - help me gents
 

Could be?
What I would do is get a can of carb cleaner, fire up your rig and now spray the fluid around your booster, being careful and watch were you spray, when you hear your rpm go up you have found the vacume leak..depending on were it is will steer you to the fix :metal:

Good Luck
Burt

Re: Vacuum issues - help me gents
 

Yep, you need a new booster! You can also pinch the vac. hose to the booster with pliers while the engine is running to verify it, but I'm sure that's what it is.

Re: Vacuum issues - help me gents
 

I would isolate the problem by disconnecting the vacuum line to the booster and see if it goes away. Also a cheap vacuum gauge is very helpful.

Good luck

Re: Vacuum issues - help me gents
 

Replaced all my vacuum lines and Booster, truck would not idle. Quit counting the turns of the idle screws at 6. Takes about 12 foot to replace all your under dash ones.

Re: Vacuum issues - help me gents
 

funny thing is i have a vacuum gage. Put it in couple weeks ago in the blank spot next to the oil pressure gage. It really doesn't show that im low on vacuum, although my brakes have never work very well. I wrote a thread a while back about switching to a hydraboost. I bought one but never installed it. Maybe I've have a bad booster since i bought the rig.


Beside...... brakes are overatted, all they do is slow you down.

Re: Vacuum issues - help me gents
 

Sounds like now is a great time to swap to the hydro set-up..

Re: Vacuum issues - help me gents
 

What I did is upgrade my booster to 1ton.
1/2ton truck have a single diaphram booster were 1ton uses a double.
WOW! I can actualyl lock up my 35" swampers now. HUGE improvement.
Simply when to Autozone (they carry AC Delco) and ordered a Master/Booster set for a 1972 K30 1ton 4x4 p/u.
My brake are better than ever!
Burt

Re: Vacuum issues - help me gents
 

damn...i got to this post after i bought a replacement booster. That was the problem. The brakes work a little better, but the biggest thing is the vacuum leak is gone. Now i kinda wish i would have bought a 1 ton booster. I cannot nor have i ever been able to lock my brakes up.

Re: Vacuum issues - help me gents
 

I put in a 1 ton too. Got it a while back in the yard. Works good. I've considered hydro-boost, but abandoned the idea. Just more hoses to leak and when your power steering pump takes a dump you loose your brakes. Another way to decrease brake effort is to get a master cylinder with a smaller bore. That's right a smaller bore increases brake pressure and reduces effort.
Well at least you fixed your vacuum leak. Another good way to check for vacuum leaks is by squirting water. Works like a can of carb cleaner, but makes a nice slurping sound when you find the leak and it makes the engine rpm drop when sucked in.
"If at first you don't succeed, keep on sucking 'till you do succeed" - Curly Howard