bbrideau

So start with the good. Im safe, trucks safe.
The bad.
Was driving down the highway at 115 kmh which i think is about 65 mph.
noticed my truck starting to slow down then my brakes locked up front. i managed to pull off to the side of the road. could not move my truck unless i pretty much redlined and popped the clutch. brake pedal is super stiff and both side on the front could fry an egg in seconds. About a week ago it did this to me leaving work but it cleared up before i could even get out and look. Then afterwards the odd time my brake pedal would be really sloppy then returned to normal. Now the SOB's wont budge. I left the truck to sit for hald an hour and they started to free up again, now the truck is sitting on a side road off the highway til tomorrow afternoon. I got new calipers pads and rotors because they are probably warped/glazed and look to be original to the truck. I know the chances of both calipers siezing at the same time are slim to none but it is still possible. But my guess is probably master cylinder? Any suggestions?


PS i tried removing the vaccuum line from the booster to relieve any vaccum pressure and it didnt help at all. All my lines are good fluid is good and hard lines have no pinches in them or cracks.

thanks for the help YT!

EDIT it is a 88 T4R 22re

justin_4runner

replace the master its building up pressure and not releasing, i heard of another buddy of mine doing this and it was the master that was causing the issue.

gennro

Sounds like time for a brake system repair/cleaning. I am surprised how many people run around with 10+ year old brake fluid. I suggest at least rebuilding the front calipers while you are at it or replacing them. Rockauto.com carries most of our brake system parts for a decent price.

James Woods

iTrader: (1)

A master cylinder wont apply pressure itself, it is a mechanical component that has to be pushed to push fluid into the lines and the shaft inside cannot move itself. What your buddy probably had was some old brake fluid that had absorbed water because most brake fluid is hydroscopic. When enough water is absorbed into your brake fluid, the boiling point is lowered and when you apply the brakes on the freeway and the calipers at the wheels get hot, the heat transfers to the brake fluid inside and makes the fluid boil in the lines and the master cylinder which raises the pressure in the lines and locks up the brakes. I am sure that at least one of the calipers was sticking a bit generating constant heat which helped create the problem.

I agree with gennro, replace the calipers or rebuild them and make sure to give your brake system a good flushing but make sure to put your cap back on after topping off the reservoir while bleeding them so your fluid doesn't absorb moisture again.