So I just got back from a Baja trip and my brake system started giving me problems on the way home. So here is how it started. . .

I parked the truck with the E brake on for two days (never use the E brake because it sticks and takes a few miles of driving before it releases enough to stop annoying me) so when I drove off after day two the pedal was really hard and the tires would slide on the gravel every time I pushed hard enough to get the truck to stop. It has done this before (slide tires, not hard pedal) and it usually goes away after a few brake applications. So I thought nothing of it. Well, 1600 miles later it's still doing it when I got home (minus the sliding tires). I thought the hard pedal was just from the semi stuck E brake, so I took apart the drums and released the E brake (wasn't really that stuck but hanging up a little) and replaced the brake shoes. I thought that would cure the problem but it hasn't.

On a side note I noticed that on the way home my vent blower wouldn't blow anyway other than out the defrost vent. . . I thought this was just another unlucky break but in reading a past post this may have something to do with the vacuum pump?

After replacing the brake shoes I noticed that the pedal really isn't that hard at the start of braking but rather just stiff and then bleeds down and starts braking better as the pedal bleeds down a little bit (note: the pedal doesn't bleed to the floor, merely just an inch or so).

I also noticed that the vent will blow out the other vents now but only on occasion is this an indication of a failing vacuum pump?

Any thoughts would be greatly appreciated! I need the truck working by the weekend for a road trip, would hate to drive another 2000 miles with shotty braking, there's some steep hills to go through too, I'm a thrill seeker but not the, runaway truck on a 20 deg slope with hair pin turns, type thrill seeker.

Thanks, ken

Oh and on another side note, I don't know if it's relevant or not, but my truck has had a case of "the drip" when I was on the trip. It drips unknown fluid from a mythical place on the drivers side, just at the start of the bed (pretty much between the cab and bed). It dripped for about 4 days while in baja. I thought it was a leaky ice chest but once they were removed the truck continued to drip for a few days. It's not a ton of fluid but maybe a drip ever several minutes. I touched and smelled it to make sure that it wasn't fuel and it doesn't have an odor (does brake fluid?). Maybe a cracked brake line? The brake fluid reservior is still at max level and I would think that it would be bleeding down if it was brake fluid??? but I don't know.

 

I've replaced almost all of the brake components on my 85 f250, now I have great brakes! You need to start eliminating variables....

How about replacing the E-brake cables? Only about $15.00 each, well worth it if you avoid sticking cable wiping out drum and shoes? I avoided replacing mine for a while, but I'm glad I did it.

Check all of your brake lines visibly. If they have heavy corrosion, replace them... Don't wait for one to pop like I did... I bought the flange tool and bent my own lines, saved a lot of $$$.

I've read on the list that some vent issues are brought on by weak vacuum.. Again, eliminate the variables... Plug the vacuum line to the dash and see if your brakes are any better... Better yet, get a vacuum guage and start testing... Start at the pump and work your way out... Plug different components and test.

Drip could be brake fluid.. Put something clean and clear under the truck to catch it... Smell it, then pop your master cylinder and smell that, if they smell the same you've found your source.. Could be the master cylinder leaking...

Though, stiff pedal sounds like booster is not coming on, again, vacuum testing could find this...

 

Well with your vents not acting right and hard brake pedal, you either have a broken vaccum line or your vaccum pump has quit. It is either one of the two I 100% guarantee it.

 

So, I replaced the master cylinder and it turns out that's not the problem. Figured that I would start with the cheapest part first and it didn't help anything. On the bright side, I have a new part in my truck and one less possiblity.

Next looks like the power boost. I pulled the vacuum line off the vac pump and it's sucking like a hoover. Somehow my vents are working again but the brakes still aren't.

Thanks for the help guys, Ken

 

Pull the line out of the brake booster, see if blocking that line gets the vacuum up so the vents start working right.

What year is the truck?

What transmission does it have?

C 6 has vacuum controls and could be where the vacuum is going.

If you have cruise control, that is another place you could be losing vacuum.