HELP! Vacuum pump/booster issue!

[smooth]

Okay, I replaced my vacuum pump since my pedal had been getting hard and it had been making noise. There's a long story here about me ending up having one of the wierd Jan-March 1992 pumps, but I digress.
I put on a remand Cardon pump, second trip out lost power brakes. Took it off today and the internals had failed. Got a new Dorman pump, put it on, and replaced all of the vacuum lines and now I'm losing vacuum at the booster. I can have it all hooked up, all the lines in place and only get 6 lbs of vacuum. I take off the line to the booster and plug it with my thumb and vacuum jumps up to 21 lbs. I replaced the grommet and check valve, same problem.
Is it possible the failure of one caused the other to fail, or is this just some twisted joke to fate that they both failed at the same time (or both the booster and the old vacuum pump were failing together)?
Anyone have any thoughts on this? the leak is definitely at the booster. I plan on taking it off tomorrow, is there a way to check it by hand beyond what I am doing?

Please help!!!

MoMo

 

[MR.T]

Did you happen to test if the old vac pump had good vacuum (by itself)? I can't make a good argument for a booster leak killing the vac pump or vice-versa. Sometimes unrelated coincidences happen, like winning a multiple brake problem lottery (and reman parts increase your chances). In any case, the old vac pump was noisy, so it probably was going to fail in the near future if it hadn't already -- no money wasted.

 

[smooth]

It was pulling 19-20 lbs at idle, I had heard 21 was bare minimum. Plus, my cruise would work, but couldn't hold the speed under load (i.e. going up even a slight incline, the speed would slowly drop off and eventually drop out of cruise) so I figured the vacuum pump was going. Once the pedal started getting harder, I figured it was time to replace it. But now, the brakes are rock hard. I guess the booster could have been on the way out as well.

MoMo

 

[gatorman21218]

Did you happen to test if the old vac pump had good vacuum (by itself)? I can't make a good argument for a booster leak killing the vac pump or vice-versa. Sometimes unrelated coincidences happen, like winning a multiple brake problem lottery (and reman parts increase your chances). In any case, the old vac pump was noisy, so it probably was going to fail in the near future if it hadn't already -- no money wasted.

I won the dagone brake powerball not too long ago. Anyway could a leaking booster cause the pump to work harder thus wear out faster?

 

[MR.T]

I won the dagone brake powerball not too long ago. Anyway could a leaking booster cause the pump to work harder thus wear out faster?

I believe it's a diaphragm pump with check valves, just can't think of how a leak would wear anything out faster. EDIT: The check valves would have more action with an air leak, so maybe that's a possible link with a long term air leak.

I won a brake lotto too, long time ago with a '69 Charger -- Brake fluid leaking from a wheel cylinder and a rear axle seal leaking too. Bought it from a guy that just screwed that car up. Took me a couple years to get it all fixed, and then the gas crisis hit, had to sell it because the fuel cost (and insurance) was killing me. Wish I still had it...

 

[BigRigTech]

Stupid question, I only ask because I'm guilty of this myself but by chance is your brake booster pushrod upside down under the dash where it snaps onto the brake pedal? I replaced a VP for no reason on my 91, during my 5spd swap I managed to rotate the pushrod 180* and it caused a vacuum leak at the firewall where the pushrod goes into the booster as it was pushing at an angle and not straight into the booster.

 

[typ4]

Stupid question, I only ask because I'm guilty of this myself but by chance is your brake booster pushrod upside down under the dash where it snaps onto the brake pedal? I replaced a VP for no reason on my 91, during my 5spd swap I managed to rotate the pushrod 180* and it caused a vacuum leak at the firewall where the pushrod goes into the booster as it was pushing at an angle and not straight into the booster.

Ya beat me to that one

And vacuum is measured in inches not lbs.

 

[BigRigTech]

Been there, done that and got the "I'm with stupid" t-shirt.

 

[smooth]

Stupid question, I only ask because I'm guilty of this myself but by chance is your brake booster pushrod upside down under the dash where it snaps onto the brake pedal?

Ya beat me to that one

And vacuum is measured in inches not lbs.

I'll check the pushrod today as I'm removing the booster, but I never removed it as long as I've owned the truck, so if it is, the PO may have done it.

As for the lbs. v. inches, sorry, I couldn't remember which it is.

So, once the booster is out, is there anyway to determine it is bad?

MoMo

 

[94f450sd]

before pulling the booster start the truk.get your head down under the dash and lightly push on the brake pedal and listen for a hissing noise.

 

[smooth]

before pulling the booster start the truk.get your head down under the dash and lightly push on the brake pedal and listen for a hissing noise.

Sorry, I replaced it already. The good news is, I had the truck running while I was under the dash unbolting it, and I could hear the air leak.

So, definitely was the problem, just really weird that that remaned vacuum pump went and then the booster went (probably already had a slow leak, but now I couldn't hold 6 in/lbs.

Oh well, it's working good now. Thanks for everyone's help!

MoMo