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The Tire Guy
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Discussion Starter · #1 ·
I have noticed lately that my brake fluid gets low rather quick. At first it was just every few months when I would check it I would have to top it off, but never thought anything of it. My pedal has been soft as long as I can remember so I always thought it was the nature of the truck. Yesterday my brake light (e brake) came on so I checked my fluid, LOW,LOW,LOW. So I filled it back up and about 6 miles later it was almost empty. This morning me and my mechanic looked at it and came up with the master cylinder gone and was leaking into the brake booster. There was no visible fluid on the truck or ground anywhere, that's where we came up with the leak into the booster. Any thoughts or ideas??
 

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I have noticed lately that my brake fluid gets low rather quick. At first it was just every few months when I would check it I would have to top it off, but never thought anything of it. My pedal has been soft as long as I can remember so I always thought it was the nature of the truck. Yesterday my brake light (e brake) came on so I checked my fluid, LOW,LOW,LOW. So I filled it back up and about 6 miles later it was almost empty. This morning me and my mechanic looked at it and came up with the master cylinder gone and was leaking into the brake booster. There was no visible fluid on the truck or ground anywhere, that's where we came up with the leak into the booster. Any thoughts or ideas??
Had to Google this one

Brake Booster

Master Cylinder

Does this mean that ultimately you are sucking brake fluid out of the master cylinder and into your intake? Pretty scary thought there Rew . .. Wow - maybe time to do an oil analysis and find out definitively if there is brake fluid in your engine oil.

Keep us posted buddy.
 

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2015 Toyota Tundra DC SR5 5.7L
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Does this mean that ultimately you are sucking brake fluid out of the master cylinder and into your intake? Pretty scary thought there Rew . .. Wow - maybe time to do an oil analysis and find out definitively if there is brake fluid in your engine oil.
I didn't know that was even possible...
 

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Yhea its possible. I have replaced a couple of boosters in the past that lost the ability to hold vacuum and operate the master correctly they did have some fluid in them. Usually a master will seep down the front of the booster though when they go bad and start leaking. Did you check your rear wheel cylinders as well?

Easiest and cheapest way to see is to pull the master off and see if the inside of the booster is full of fluid.
 

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Does this mean that ultimately you are sucking brake fluid out of the master cylinder and into your intake? Pretty scary thought there Rew . .. Wow - maybe time to do an oil analysis and find out definitively if there is brake fluid in your engine oil.

Keep us posted buddy.
correct me if i am wrong but i thought there was a check valve?
 

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The Tire Guy
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261 Posts
Discussion Starter · #7 ·
So IF, the fluid isn't in the booster then it would have gone into the intake?? That's fun to think about! There is the yearly car show in town, maybe I should start looking? I haven't pulled it yet but as soon as the parts show up I'll take a look at what is going on, snap some pics as well.

Highway, could this be the mysterious mpg problem?:clumsy:
 
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