Put your gauge on the manifold, then pinch off one hose at a time until you get vacuum at the manifold. That will at least tell you which area to start looking at.

 

I pulled the hose off of the manifold that runs into the booster through the valve and tried it from there with no vacuum obtained at all and then I took the valve out and put it straight into the grommet on the booster and nothing but I don't feel like I got a good seal on it there. I'm going to have to find an adapter large enoughfor that hole.
I was able to get vacuum from the end of the hose that hooks up to the valve equal to what I got straight from the pump itself so that makes me think that it's good at least until that check valve. Could that be an incorrect assumption though?


I'm also wondering how to check the HVAC vac system? I've seen that it can be the source of a leak but I don't know where to start with it either.

 

Well I finally found the diagnostic directions for vacuum and HVAC vacuum in the shop manual. I'm not positive on where/what each thing they refer to is but it's at least more knowledge than I had before so we'll see how it goes.

 

You are welcome. Maybe this helps you a little more:

Pinpoint Tests

PINPOINT TEST N: EXCESSIVE PEDAL EFFORT, VACUUM BOOST SYSTEM

N1 VACUUM CHECK

l Disconnect vacuum booster hose from booster.

l Connect Rotunda Vacuum/Pressure Tester 164-R0253 or Rotunda Vacuum Tester 014-R1054 or equivalent to the vacuum hose with a T-fitting.

l Key on, engine running. Allow engine to reach normal operating temperature.

l Record the vacuum pressure.
l Is the vacuum reading 57-70 kPa (17-21 in-Hg)?
Yes
GO to «N2».
No
TUNE UP or REPAIR as required.

N2 SYSTEM INSPECTION

l Key off.

l Reconnect the vacuum line.

l Inspect power brake booster check valve, rubber grommet and all vacuum plumbing for cracks, holes, bad connections or missing clamps.

l Push down on brake pedal and hold.

l Key on, engine running.
l Does the brake pedal move downward when the engine is started?
Yes
Vacuum system is OK.
No
GO to «N3» for diesel engines. GO to «N4» for gas engines.

N3 VACUUM DROP CHECK, DIESEL ONLY

l Key off.

l Disconnect the vacuum line and connect a vacuum gauge with a T-fitting to the lower part of dash-mounted plastic check valve.

l Key on, engine running at idle until vacuum reaches 57-70 kPa (17-21 in-Hg).

l Key off.

l Observe vacuum gauge for 1 minute.
l Does vacuum pressure drop more than 1 in-Hg?
Yes
REPLACE power brake booster check valve.
No
GO to «N4».

N4 COMPONENT ISOLATION CHECK

l Key off.

l Reconnect the vacuum gauge to the same point as in Step N1, but leave the rest of the system connected.

l Key on, engine running at idle until vacuum reaches 57-70 kPa (17-21 in-Hg).

l Key off.

l Observe vacuum gauge for 1 minute.
l Does vacuum pressure drop more than 1 in-Hg?
Yes
DISCONNECT each component one at a time and REPEAT the test procedures in N4 until the leaking component is found. PLUG the disconnected vacuum line while performing the test procedures. REPAIR or REPLACE as required. On diesel engines with dash-mounted power brake booster, REPLACE power brake booster check valve also.
No
GO to «N5».

N5 BOOSTER LEAK CHECK

l Key on.

l Run engine until vacuum pressure reaches 57-70 kPa (17-21 in-Hg).

l Key off.

l Push down on the brake pedal and hold for a few seconds and release.
l Does the vacuum drop to 0 kPa (0 in-Hg)?
Yes
REPLACE power brake booster.
No
System checks OK. REMOVE vacuum gauge and RECONNECT all vacuum lines.

 

VACUUM PORT.

Front to rear on the vacuum port:
-the first goes to the pump,
-the second to the switch,
-the third small hose to the heater - air controls
-and the fourth to the brake booster.
I think the brake booster was changed in 97.

 

If you have left everything else but the booster hooked up (I assume this is what you mean by saying that you tested it at the line without the valve) and you're getting good vacuum, it sounds to me like you need a new booster. That or a hydroboost system.... 'jus sayin'....

 

Yessir. I think we're on the same page there. Would a bad booster also cause an HVAC issue or is that just potentially a separate issue altogether?

 

A bad booster could cause you to lose vacuum, which could cause the loss of the use of your HVAC controls. I believe the Hot/Cold control should still work since it is cable actuated, but the blend door is all vacuum controlled, IIRC. I would say they could definitely be related. FWIW, I have a couple of good brake boosters from my parts trucks. I would be happy to make you a deal on one if you don't want to spring for a new one. I know you're trying to sell the truck and all and I can imagine you don't want to sink a bunch more money into it just to turn around and sell it. PM me if you're interested.

 

Remove the line to the booster, either end, and PLUG it. Then start the truck and try working the HVAC controls. If they work, that confirms the booster is not only bad, but consuming enough vacuum to render the HVAC inop.

 

Thanks man. I just may take you up on that offer. It may be a little while though. As for selling the truck, I'm not really advertising it at all anymore. After having the cclb parts truck mama was wanting a crew cab(not to incenuate that I don't as well) and I had some money saved up. There were quite a handful of NICE OBS cclb's with 300k+ miles on them. Plan was to buy one and swap my stuff to it and sell the ext cab. Then mama decided she wanted a house sooner than we had originally talked about, which considering the current market, is probably the more responsible choice. Anyway, that's what the saved money is going to now. And I'm not exactly bummed because I love my truck. So to make a long story longer, I'm taking care of it just as I always have since there's no telling how much longer I'll have it.

That's a good thought. Soon as I find a good plugging device I'll give it a try. Thanks man.

 

Cool beans! I am glad to hear that you're planning to hold onto Redman. You're going to need a good truck if you're about to become a home owner!

Let me know if you end up needing a booster. I have two extras.

I would either plug the hose with a golf tee, cork, bolt, etc, etc, etc or just pinch it off with a c-clamp, vice grip, or something similar.

 

I got out there to look into it some more today. I removed the line from the check valve and occluded it. The HVAC operation didn't change just a whole lot at all. Still quite delayed when changing zones. So I got to looking around and found that the yellowish hose in the picture is all kinds of rotten and has a hole in it.

I don't know which vac hose that is, where it goes, or what that valve is it operates. I plugged one of the holes with my finger and the arm on the valve would draw in and release as soon as I released the hose. I'd like to fix that and then start the diagnosis process again to see if there's anything else.

On another note. I dropped a plug from my vac pump/gauge INTO the brake booster. I can see it down in the bottom but have NO idea how to get it out or if it will hurt anything to stay. Regardless, I kinda need it so I've got that to figure now.

Thoughts? Advice?

 

I don't suppose the plug would be magnetic would it?

 

Man I wish. Best idea so far is I think I'm going to sharpen a wire and try to impale a piece of it that won't be affected and pull it out.

 

Jacob look this link

https://www.ford-trucks.com/forums/8...-this-for.html