My truck, this issue has been an odd one, think its the brake booster but till I can get paid at work, I can't afford to replace everything and hope it fixes it.

Basically, I have manuel brakes as I call it, I use a bit of muscle on the brake pedal to stop the truck and every now and then, I get power assist. I can feel the ABS working (side note) but just have to do all the braking work myself.

Right now I just do basic trips to and from work, random trip here and there but I have family that wants me to visit and I don't want to go till the brakes are back to normal.

The can (bake booster) under the hood with master cylinder looks good (for its age) no damage and whatnot.

I'm wondering if the brake booster can be rebuilt if its the problem. I dont want to take it apart if its something that cant be put back together and leaves me without a vehicle to even get to work.r

Any help?

 

A lot of the boosters the parts stores sale are re-manufactures, but I've never seen a kit for a do it your selfer. Boosters tend to be inexpensive though and not too difficult to change.

Keep in mind though that the IDI uses a vacuum pump that provides the vacuum to the booster and the HVAC controls, (and the modulator on a C6). These do wear out. There are quite a few threads in this forum on testing them, I'd check it out before trowing parts at it.

 

vacuum pumps on the earlier model's were a common problem, just take the belt off of the pump, under the alternator and spin it by hand you should feel the pump sucking air with the resistance on every turn.

 

I'll take a look at the vac pump and rotate it by hand, I know its the pump from the 6.9 engine when I swapped for the 7.3 as it felt stronger.

Should I feel resistance when turning by hand or should it turn fairly easily.

I'll have to check around and see if I still have the vac pump from the 7.3

 

Just a random thought but, would it be possible to convert to a electric vacuum pump.

Only reason it popped into my head is I have a nice little vacuum pump off a decommissioned ambulance...

What is the vacuum pressure the truck generates for normal operation?

 

The truck (any diesel engine) doesn't generate vacuum; thus the pump. The pump should produce at least 20 inHg at idle. I don't think any electric pump could produce enough vacuum to operate the brake booster. For that, it's not just the vacuum level, but the volume of vacuum it can produce (in effect, the volume of air it can pull).

Vacuum pump won't turn freely, you'll feel the resistance of the diaphragm. But it shouldn't be rough or scratchy/grind-y (which would indicate bad bearings). You'll feel the resistance go up and down as the diapragm "cycles". It typically makes a sound like you might expect from a cheap sound effect of a duck quacking.

 

There are many guys that replace the mechanical vacuum pump with electric one on these trucks

https://www.ford-trucks.com/forums/1...mp-delete.html

 

FIRST LINE of the FIRST POST of that thread is:
Have any of those "many guys" done this and retained the vacuum brake boost? I have yet to see one.

 

If you've got a large electric pump(not, like, the tiny ones they put in the later model Ford Powerstrokes), you can probably do it; You'll know right quick if it's going to work or not.
Even if it doesn't have enough volume to handle it, it may still work, what with the large vacuum reservoir -- a mostly-shot mechanical pump doesn't have enough to do it either(like on my newest truck), but I still get brakes... for about two pumps in a given minute. Then I lose assist until the engine catches up.

I will point out, however, that I opted for Hydroboost in my main rig. I hacked every bit of it, using a totally wrong(but cheap!) unit from an 03. It works *so much* better than any vacuum booster I've seen that I fully intend to do the same to my other rigs as soon as I can find donor parts.

 

Been a bit, finally got around to checking up on things, especially since I ended up with no power brakes lol...

Got the Vac pump off, no vacuum at all it seemed. Got a new pump, big difference, lots of vacuum on first rotation.

A power steering pump pulley ground down worked to pull the pulley and a long bolt, washer, and nut to install the pulley (not going to pay almost $30 for a tool to install the pulley).

Quick test drive, Power Brakes... So happy, one more thing fixed, vac pump has a lifetime warranty so that's all good for ever replacing it again.

Now to other issues...

Thanks for setting me on route to the vac pump rather than the brake booster.