92 Ford F350, 7.3 IDI, with Banks turbo; BRAKE issues.

[ridgerunner]

I need to get some helpful advice from the seasoned Ford diesel owners. I've got a 92 F350, just completed a engine swap, truck had sat for @ 4 years. No brakes, hard pedal. So, I replaced front brake calipers, flex line, master cylinder, brake booster, rear wheel cylinders, shoes, got a good bleed, drove truck for a month, lost brakes going to work, extremely hard pedal; had to use e brake to avoid accident. Found the vacuum pump was bad. Changed vacuum pump, with a known good one, drove another 2 weeks, and hard pedal again; with only 1 good brake application, then no brakes. Took the vacuum manifold out of the picture, ran vacuum hose straight from the pump to the brake booster; no difference.

So, I put a vacuum guage in line. At idle, 22" of vacuum. Apply the brakes, 1 slow application, vacuum drops to zero until brakes released. Vacuum builds back to 22".

I've read where where someone said there should be 25" all the time at idle.

So, I bought a new vacuum pump, with same results as before, 22" at idle, 1 application of brakes, vacuum goes to 0 until brake pedal released.

Now; I'm almost sure it has to be a bad booster, but I'm getting burned out with these brake issues.

Need some suggestions.

Thx in advance.

 

[icanfixall]

Welcome to the forum. From all the information you have listed. This vacuum issue has to be a bad brake booster. I do not feel you have another bad vacuum pump but funnier things have happened. On the bright side of things you now have good new brakes because of all the replaced parks.
Now normally if the brake peddle is hard that means you lost vacuum. The loss of vacuum can be a bad pump. A bad hose or a bad booster.

 

[sassyrel]

how goods your hearing??? with truck running, it may be impossible,,to hear a vacuum leak..but, changing the engine,,you may have cracked a vacuum line somewhere. large or small...or cracked the vac manifold on the firewall.......

 

[ridgerunner]

Thanks for the replies. The vacuum hoses are good. I've done all this work after engine swap. The month I was driving it, it had good reliable brakes. I hadn't done the rears then. But now, its new all the way around. Like I said, I had the vacuum guage tee'd in, when applying the brakes and vacuum went to zero, hard pedal, no stopping power.
It's not even safe to drive this way.

 

[riotwarrior]

My guess is booster too....

Now if yer in for a penny....look for a complete Hydroboost and install that instead.

JM2CW

 

[cpdenton]

It sounds like a bad booster to me. Time for another one.

It may be time to swap in a hydroboost brake system from an f-superduty. There are many threads on here. If you are tired of an crappy pedal feel, the hydroboost will forever fix that.

To me, it is the best mod I have done to my truck behind the turbo addition.

 

[ridgerunner]

Yeah, I'm down to changing out the booster. Just can't wrap my mind around the fact its failed already.

The hydroboost system; will a new unit from a newer model bolt in or what mods have to be done?

Thx.

 

[ridgerunner]

Ok, thx for the info. I'll look around on here at the threads on the hydroboost system.

 

[BrandonBerkosky]

Just order a new hboost unit on rock auto.
I used to search the yards. But after a few leakers it's not worth it sometimes. A new one is like $136
Then u just order the lines for an hboosted ford and plumb a return in somewhere.
If anyone gives you trouble about not putting the superduty pedals in. Don't worry about it.
Personally I've never had an issue. Swapped over at least 10 fords. Not to mention ih scouts, pickups and some cars.
You won't regret it.

 

[BR3]

You said you took the manifold out of the picture right? Well darn, I was going to say check the pressure equalizer down on the wheel liner, could be dumping your vacuum......

Sent from my XT1254 using Tapatalk

 

[ridgerunner]

Ok, thx for the input. I guess I can get my money back for the hbooster I installed because it's only a couple months old.
My biggest ? is, the hboost unit will bolt on exactly where my booster mounts?
Also, the plumbing, return line shouldn't be an issue, but what about the pressure line?
Thx for all the info.

 

[BR3]

Yea it does. And you'll hafta enlarge your factory master cylinder bolt holes if you don't go super duty 1 5/16.pressure line naturally falls exactly where it should. You'll actually need two lines, one from pump to unit then uint to steering gearbox

Sent from my XT1254 using Tapatalk

 

[ridgerunner]

Ok, I'm having a little trouble picturing it. Is the steering box going to have an unused port to connect to?
The line from pump, is it the return?
So, if I just get a hbooster and mc for a pre 97 f450, I'll have what I need minuse the lines?

 

[OLDBULL8]

This may help diagnose your vacuum problem. Diagram is out of a 89 shop manual, but the 92 shouldn't be any difference. The vacuum reserve can on the drivers side is for cruise control, but also for one application of the brakes if you loose the vac pump.

 

[BrandonBerkosky]

IMO. I usually move the master out of the way install the h-boost an put the master back on. In my experience I've Never had to run the sd master.

Unless you add a barb to the reservoir or get one with 2 returns you will need to T into the return line.
Some ppl say they don't like to do that because there can be a return restriction.
To plumb the pressure side u need stock pressure line from the pump to the h-boost, pressure line from h-boost to steering box.
Then T in your return from the h-boost to the return from the box. Or add a barb to the reservior. Or get a res with the additional return.
If your lucky and you find an idi ambulance or van they use a gm style Saginaw pump and brackets that fit tighter to the engine. Then you can go get the stock pump from a gm 1 ton and it will have 2 returns on the reservoir.
Then it's all clean and factory looking without that noisy ford pump