Problem with front disk brakes on 1991 Toyota 2wd truck (1 Viewer)

[Vortec_Cruiser]

A couple months ago I suddenly began having this roblem with my truck. While driving around town, the brake pedal began getting firmer and firmer (less pedal travel), until the front brakes began dragging. It progressed to the point where the front brakes were fully locked, and the truck would not move. I opened each of the front bleeders for a few seconds to relieve the pressure in the lines. This temporarly cured the problem.

I have since replaced the master cylinder twice, with no appreciable change in the problem. The brakes have been bled numerous times since the problem began, but to no avail. When the truck sits overnight, the pedal is low the next morning, but will pump up within a few miles of mild braking. The rear drums have been working without any problems. At this point in time, I'm at a loss as to what the problem is.

 

[Cube Dweller]

Wow, good one. Does the truck have ABS?

 

[Vortec_Cruiser]

Wow, good one. Does the truck have ABS?

No, it does not.

 

[2ndGenToyotaFan]

Maybe a PO installed a line lock on the front brakes???? Somewhere between the MC and the front brakes .... wait it's both front brakes? If so then it's got to be something that effects both the front brakes.

 

[Bear80]

You should look into getting a "new" LSPV. By new I mean one out of a junk yard, a brand new one will set you back some. Hopefuly that is the problem and then you could go to 'yota for a new one.

The only other thing is that something is blocking the line. Which if it is then it is near the mc since both front brakes are affected. The front line splits right under the mc, that would be my next item to change along with the t-joint.

 

[WristPin]

if you cracked the bleeder, and fluid shot out, then the brake hoses are internally collaped.
replace hoses.
first time i have ever know of this happening to a toyota.
usally happens on pos american trucks.

 

[Jukelemon]

I agree on the proportioning valve.

It is not working properly and allowing for a build up of pressure but not a maintenance of a consistent pressure. You are probably bleeding back into the MC overnight and that is what is causing the symptom in the morning.

 

[Vortec_Cruiser]

No proportioning valve...

 

[Bear80]

your proportioning valve is located under the bed of your truck, on the passengers side frame.

 

[Vortec_Cruiser]

I forgot that this is different from my Land Cruiser. However, I really don't see how the proportioning valve could cause the problems I've experienced. All it's going to do is create more/less braking force in the rear brakes. It would not have any effect on the functioning of the front braking, and it certainly wouldn't cause a pressure buildup in the front lines.

 

[Bear80]

I really don't see how the proportioning valve could cause the problems I've experienced. All it's going to do is create more/less braking force in the rear brakes. It would not have any effect on the functioning of the front braking, and it certainly wouldn't cause a pressure buildup in the front lines.

Well I can tell you for a fact that the proportioning valve affects the front. I was having a problem with my truck where I could not get the front brakes full pressure and it was due to issues with a replacement proportioning valve I had installed.

 

[Bob_Garrett]

Is the master cylinder from Toyota or aftermarket?