Bad Brake Booster?

[rhariz21]

Hey guys need some help here. I recently picked up a 1974 2002 that was sitting for a year. replacing a fuel line got it up and driving...barely.

By barely i mean the damn thing takes all the force in the world to stop! 

Smile on my face quickly turned to worry. Thought that i was going to smack this thing into another car.

 

The brake pedal is very firm. From my experience, that should mean there isn't air in the system right? Usually air in the system equates to spongy pedal. I have to push down super hard and the car comes to a slow stop.

 

What I've done so far (not much):

- with engine off, pumped the brakes a bunch of times...didn't seem to get any firmer.. kept it depressed and started the car. the pedal did not sink down.

- Quickly Inspected vacuum line, seems to be oily 

 - sprayed carb cleaner around the vacuum hose ...no increase in idle

 

I think there is brake fluid around the booster. does that mean i have a leaky MC which lead to fluid in the booster thus killing that as well??

 

Any suggestions would help. i didn't want to start changing a bunch of parts for no reason. 

 

UPDATE BELOW

Edited December 2, 2016 by rhariz21

[Brianmc02]

How is your idle? I had the booster diaphragm rupture on my '74, and the braking effort went up exponentially, but the idle also went to hell due to the massive vacuum leak.

Maybe time to look at the calipers. Frozen calipers will give you a very firm pedal, but not much braking!


Brian


Brian McCarthy

[rhariz21]

idle seems okay. maybe a tad low ..

hmm thats a theory too

[Fatherof3]

On 12/1/2016 at 1:56 PM, rhariz21 said:

depressed and started the car. the pedal did not sink down.

 

My experience has been you will feel the brake pedal move when you start the car.

On such a light car I would think in panic mode you would still stop pretty quickly with a failed booster.

 

You may have stuck calipers and or wheel cylinders from sitting. 

Did it pull to one side or the other?

 

The wealth of knowledge here on the Faq should kick in any minute

Edited December 3, 2016 by Fatherof3

[rhariz21]

6 minutes ago, Fatherof3 said:

 

Did it pull to one side or the other?

I didnt notice any pulling. 

 

6 minutes ago, Fatherof3 said:

The wealth of knowledge here on the Faq should kick any minute

Im sure it will!!

[xr4tic]

I had the same issue on my 76.  I had to practically stand on the brake pedal to get it to stop.  It idled fine, but if I stepped on the brakes, the idle would raise.

 

Adjusting the rear drums and flushing/bleeding the whole system helped a tiny bit, but replacing the booster with a good-used one fixed it.

 

Sometimes it's as simple as making sure the hose to the booster isn't leaking and that the check valve is good and facing the right direction.  If it's installed backwards, it will stop vacuum going to the booster.

[zinz]

Sure doesn't sound like you booster is working correctly.  

 

+1 on check the fittings and line to the booster.  The line should be of the reinforced variety, meaning, it shouldn't collapse under the vacuum of the running engine.  

 

Check for fluid in the booster by removing the 90 degree, vacuum hose fitting and peering inside with a bright flashlight.  Any fluid in the bottom is a likely indicator of your problem.  

 

Don't drive it until you sort it out...

 

Centric sells a remanufactured unit, but my experience has been that if you can find a good, used OEM unit, you'll be better off... it's difficult to know if a used one is any good if it's off the car, though...  There are several threads about replacing a booster.. it can be a bit of a PITA due to tight quarters and getting wrenches on particular nuts and such, but it is doable with patience.

 

Ed

 

 

[rhariz21]

Thanks Ed. I will check the Vacuum hose, fitting, and if there is fluid inside. 

 

Any easy way of telling if its a reinforced hose?

 

i wont be driving it yet thats for sure.

 

Also, if i do indeed find fluid inside and replace the booster, does that mean the MC is bad and needs replacing or just some o-rings?

[Solarphil]

I was having similar trouble with my brakes and an old school mechanic friend told me to take the hose off the booster and plug the hose temporarily with a bolt or similar large plug, then drive down the block and apply brakes. If the pressure required is the same as before, your booster is shot. I did, mine was, and when I got a replacement it was night and day. 

 

Your hose is reinforced if when you squeeze it it doesn't collapse. It should also retain the same shape when your engine is running. 

[rhariz21]

UPDATE:

 

5 hours ago, xr4tic said:

I had the same issue on my 76.  I had to practically stand on the brake pedal to get it to stop.  It idled fine, but if I stepped on the brakes, the idle would raise.

 

Adjusting the rear drums and flushing/bleeding the whole system helped a tiny bit, but replacing the booster with a good-used one fixed it.

 

Sometimes it's as simple as making sure the hose to the booster isn't leaking and that the check valve is good and facing the right direction.  If it's installed backwards, it will stop vacuum going to the booster.

 

Had a little time after work today. Turns out xr4tic was right! The check valve was installed backwards. Flipped it around and the pedal loosened up substantially. I didn't have a chance to take it around the block but i did notice the idle would change when i pumped the brakes... Bad booster right? still need to take the plug off and look for fluid inside.

[ray_]

Cool.

 

Booster may well be ok. Pumping the brakes will disturb engine vacuum enough to make the idle jump a bit. If that's all you're getting, you may have lucked out.

 

Anyway, Zinz can help if you need to swap boosters. He can do that in his sleep now.

 

 

Cheers,

Edited December 2, 2016 by ray_

[zinz]

Good grief... that's not even a joke.  Let's see... original on the '71 failed, bought a used one and installed it.  That one failed about 6 months later.  I bought a rebuilt Centric...it last about a year and catastrophically failed while on a 2002 drive in northern Texas.  I went to the good guys at Terry Sayther's shop and they found a good used one in their stash and I've been running that one about a year.

 

The project '75 got a Centric replacement...I suppose it's still functioning for the new owner. 

 

I must have done 6 or 7 at this point on mine and friend's cars...good times.

 

Ed

[rhariz21]

wow! sounds like fun haha

Whats the secret??

[ray_]

32 minutes ago, rhariz21 said:

wow! sounds like fun haha

Whats the secret??

 

If you have a Z in your board name, you're jinxed!

 

[zinz]

HA !!!!!!  I'm double-jinxed !