brake fluid leak somewhere...

[brentleedragon]

Last night I was driving home and i was going down a hill and went to press on my brakes and the pedal went down pretty far. It took a lot of my foot being in that peddle to get it down. The brakes did work so to speak but my foot had to be all the way in it. I got it home and checked the master cylinder and the smaller reservoir was not empty but damn close. This morning I checked the drums(exterior), I checked the front brakes and can not find a leak anywhere, traced the hoses...everything can not find it. The master cylinder is less than a year old I am wondering can it be leaking into the power booster? or i mean the seal at least? Or where would be a good place to check, I am thinking im probably going to have to take the drums apart or what not to find an internal leak...

suggestions pleaseeeee!


ps it's a 79 f150 with read drum, front disc and power brakes with auto trans

 

[brownfoot]

it is going into the booster, M/C, especially rebuilt, die rather quickly
replace with a new M/C
you may want to remove the booster and drain as much as you can from it, won't be long until you will see weeping at the bottom seam of the booster, then a little while longer and the booster will die
brake fluid is hydroscopic, picks-up water vapor and then rust starts which compromises the crimp of the booster holding the diaphram

 

[LEB Ben]

Got any witness marks on the inside of any of your tires? If so, you more than likely have a leaking wheel cylinder. I've also done brake jobs with my dad where the leak wouldn't show up until the car was on and then brake lines would leak like a sieve. So you may wanna try having someone you trust turn the truck on, put it in gear while remaining on the brakes and you duck under and see if you see anything.

 

[73F100Shortbed]

If only the small cylinder is emptying out check rear wheel cylinders. Just because the tires aren't wet does not mean they aren't leaking. Also the M/C could be leaking but I would check the backs first.

 

[brentleedragon]

Yeah i'll check, I'll have to pull the tire off to be sure because it's pretty dry all around there. I'll check what you said too Ben.

 

[chuck101st]

Ditto Ben and Sean's remarks...I have a wheel cylinder that is leaking and have to add fluid about once every 2 weeks..Doesn't show outside though.

 

[Fellro]

How often do you check your brake fluid levels? It may be a leak over time. I have had small losses over time with leaking rear wheel cylinders that don't show any loss, but the fluid keeps going down to have to be topped off every other month or so.