Heres the deal. It seems it got colder, my truck decided to start with the problems. This one is a more main one, and I need an inspection at the end of the month.

When I go to stop, if I press the pedal slowish it goes all the way to the floor before the breaks come on. If I press the pedal quick its rock hard and it seems everything is normal. Its worse when the truck it first started. Not RPM related.

Having limited access to a shop and the temps being in the single digits, the only thing I have done so far is visualy checked for vacuum leaks and bled the breaks at all 4 wheels till fresh fluid came out. Couldant see any leaks and my fluid remains full.

This weekend when I can being the truck inside, well go at the system with a vacuum tester which should give us a better idea whats going on.

Any imput or places to check would be great. I have another master cylinder off a 95 4runner that we were planning on swapping out, but I dont have the booster. I should have grabbed it, it went to the scrap yard with the rest of the truck. So if I have to get one of those I will, they are just a little pricey to be changing on a whim.

Thanks in advance.

 

i had a problem similar to this and the cause was a brake line had a small hole. maybe check your break lines?

 

When you hold your foot on the pedal, does it slowly sink? Most likely a bad master brake cylinder. $50 at Autozone.

 

could be the master cylinder or the booster or booster vacuum lines. try bleeding the master cylinder. also, check the booster and the vacuum.

 

Had the same problem on mine and it was the vacuum/brake check valve, it was sticking because of moisture in it. Only when cold obviously, (gets frozen) and once it warms up it goes away.

 

*Brake.

 

x2 on the Brake Check Valve.

 

mb4- Is that the valve between the booster and the engine? I was thinking about replacing that.

Auto parts store (bond) wants 170ish for the booster, nix99 quoted me 60 shipped.

I have a master cylinder off a 95 4runner v6 that I might try.

Thanks for the responses!

 

Yup exactly, strangely enough, I found a temporary way around it before I fixed it. Whenever my pedal got rock hard, I would put my foot beneath the brake pedal and push upwards. (Opposite of pressing the brakes down) For some reason that freed it up.

 

Went to 2 parts stores on the way home. Neither had it or knew where to get it. Ill swap it out with the one on my parts rig this weekend. See it it helps.

Both guys at the parts store old me they thought it was the o ring on the back of the master cylinder. Im going to try the V6 one this weekend. Will it just bolt up to my stock booster?

 

Pressure tested everything, it all checked out good. Pulled the master and it was leaking out the back. From my internet searching I think that they V6 master I have would not work with my 4cly booster. Napa had the stock one in stock. Installed it and I have breaks again!

Also changed the starter and put on the tale pipe. Should be all ready for inspection now. Did it all in the brisk 25 degree day!