Braking power intermittent loss (1 Viewer)

[divemedic]

ive been experiencing intermittent power loss with braking. It feels like a loss of vacuum at the brake booster. I only experience it during light and long-duration brake application (slowing for an off ramp or red light) I always feel pressure build once a specific pedal travel is reached or I reapply the brakes. Toyota master tech couldn't find anything wrong and stated it was normal for the design of the calipers once the brakes pass a certain ware point. He stated I was at about 40% all around. Advice?

 

[Julian Stead]

Possibly the accumulator is losing efficiency or it is normal as if you lost braking assist you would be panicing more than you are now. I think you are feeling the pump rebuilding pressure.

 

[uHu]

Sounds like a master piston wear issue to me. Was the master ever serviced? Always used t0yota fluid? How many miles?

 

[divemedic]

I'll need to dig into mx records to check master cylinder hx. Truck has 319k miles currently. How often should the master cylinder be serviced?

Do you mean the accumulator in relation to the brake booster?

 

[divemedic]

It seems the cold weather effects this issue. We're having a warm spell today. It's mid 40's as opposed to the teens and single digits. Any input?

 

[Julian Stead]

When was the last time you had your brake fluid changed. The only thing I can think of is that you have some water build up in your system and you are experiencing some brake fade.

 

[Spike555]

Sounds like brake fade to me.
Your brakes are getting to hot and loosing stopping power. Let off, they cool, reapply and all is well until they get hot again.
Thinner brake pads will heat up faster, old brake fluid will boil faster. Both cause brake fade.
Flush brake fluid first. This should be done every 2yrs anyway.

 

[fooldall1]

Damn, a lot of brake issues lately with all this cold..

Is that the usual effect of cold weather?

 

[divemedic]

These trucks are now starting to hit toyota's intended shelf life of 20 years I think.

 

[Spike555]

Damn, a lot of brake issues lately with all this cold..

Is that the usual effect of cold weather?

The cold won't have any effect on the brakes. Maybe with the booster or master cylinder but not the calipers.

 

[fooldall1]

The cold won't have any effect on the brakes. Maybe with the booster or master cylinder but not the calipers.

Yeah, that I knew.. I was just wondering if the cold was affecting the Pump/MC/Accumulator in a bad way- or MAYBE the cold and recent posts about brake issues are just a coincidence.

 

[uHu]

I see that the booster works a bit harder when cold. I suppose the fluid might be slightly thicker, and there might be problems with moisture in the motor, making the dust from the brushes conduct better and "steal" some power.

 

[Spike555]

I see that the booster works a bit harder when cold. I suppose the fluid might be slightly thicker, and there might be problems with moisture in the motor, making the dust from the brushes conduct better and "steal" some power.

I had never thought of that. Definetly food for thought and another reason to flush your brake fluid every 2yrs.