Losing brake fluid very slowly. Where from?

Sporin

Sporin

New member
About a month ago I had the ((BRAKE)) warning light come on under acceleration. I deduced it was a slightly low level in the reservoir, added some more, and the light went away.

I just saw the light again today and, presumably, need to do the same thing.

Obviously something is wrong.

So... Where do I look first? It's cold, wet and snowy all the time here now so crawling under the truck will be tough. If anyone has a suggestions as to where to start my search I'd appreciate it. Thanks.
 
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Sporin said:
About a month ago I had the ((BRAKE)) warning light come on under acceleration. I deduced it was a slightly low level in the reservoir, added some more, and the light went away.

I just saw the light again today and, presumably, need to do the same thing.

Obviously something is wrong.

So... Where do I look first? It's cold, wet and snowy all the time here now so crawling under the truck will be tough. If anyone has a suggestions as to where to start my search I'd appreciate it. Thanks.
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Well, typically, it's probably going to be your master cylinder OR a leaky caliper. Clearly, a leaky caliper is a cheaper fix. The master cylinder is insanely expensive as there is no "rebuild" kit for it. I would start by pulling off the front wheels and CLOSELY inspecting your calipers; followed by the rear wheels; followed by a close inspection of your master cylinder. I hope it's a caliper. GOOD LUCK!
 
Put pieces of cardboard under each wheel next time you park. Just tuck them in under tires after you park. Pump the brake pedal too to create a little extra pressure in the system and wait overnight. This should reveal if there are any caliper leaks. Plastic bags under the cardboard if the ground is wet.
 
Thank you. Yes, I'm worried about that pricey master cylinder is well, but this started happening (along with some funky brake feel) right after I got my new tires. So I'm wondering/hoping that it is something at the caliper (way cheaper)
 
Leaving it with my mechanic on Tuesday, it's totally got me paranoid about the $$MC$$. :puke:

Fingers crossed that it's a caliper or a line or something.
 
Sporin said:
Leaving it with my mechanic on Tuesday, it's totally got me paranoid about the $$MC$$. :puke:

Fingers crossed that it's a caliper or a line or something.
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If you don't see fluid leaking from any of the lines going into/out of the master cylinder and there's no fluid on the fender area under the master cylinder in the engine bay. I'd say the leak is down lower.
 
Sporin said:
About a month ago I had the ((BRAKE)) warning light come on under acceleration. I deduced it was a slightly low level in the reservoir, added some more, and the light went away.

I just saw the light again today and, presumably, need to do the same thing.

Obviously something is wrong.

So... Where do I look first? It's cold, wet and snowy all the time here now so crawling under the truck will be tough. If anyone has a suggestions as to where to start my search I'd appreciate it. Thanks.
Click to expand...

The first mistake you made is assuming anything…first i would sit in the truck engine off and pump the pedal and see if it gets hard, or to see if it fades…you should be able to stand on it without it dropping. Since Brake fluid is basically hydraulic fluid, a low reservoir to indicates that the brake pads are almost worn down and if the light is actually coming on you likely need pads on all 4 corners….IF!!!! there is no obvious leak….good luck!
 
LobstaMobsta said:
The first mistake you made is assuming anything…first i would sit in the truck engine off and pump the pedal and see if it gets hard, or to see if it fades…you should be able to stand on it without it dropping. Since Brake fluid is basically hydraulic fluid, a low reservoir to indicates that the brake pads are almost worn down and if the light is actually coming on you likely need pads on all 4 corners….IF!!!! there is no obvious leak….good luck!
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lol... You know sometimes I am so used to what seems "common sense" to me that such simple things tend not to occur to me. :spit:

I'm usually very aware of roughly how much brake pad material I have left in the 4Runner, but I could see someone not as anal retentive as me going long stretches without looking at them.

Yeah, if the reservoir was just a bit lower than usual; you're brakes are probably just getting towards the end of their life. See if you can shine a flash light through the spokes and see how low they are.
 
BlackWorksInc said:
lol... You know sometimes I am so used to what seems "common sense" to me that such simple things tend not to occur to me. :spit:

I'm usually very aware of roughly how much brake pad material I have left in the 4Runner, but I could see someone not as anal retentive as me going long stretches without looking at them.

Yeah, if the reservoir was just a bit lower than usual; you're brakes are probably just getting towards the end of their life. See if you can shine a flash light through the spokes and see how low they are.
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This is what my mechanic said over the phone, that the amount I've added is actually very small and it could need just pads.

Pads up front were reflectively new (as were the calipers) when I bought it from the dealer but I've never looked at the rears. I don't see any fluid around the MC under the hood so I'm hopeful this isn't too bad.

Braking is always very, very good. Strong, firm pedal, never any issues before I started feeling the feedback or since.
 
Sporin said:
Braking is always very, very good. Strong, firm pedal, never any issues before I started feeling the feedback or since.
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If this is the case, I doubt you are losing fluid. The pedal would be soft, because if fluid can get out, air can get in. Probably just worn pads as others have said
 
This was my issue last summer! Took me the longest time to figure it out mostly because of where the fluid was dripping down was NOT helpful to what part actually was failing. Simply what was bad was the hose from the reservoir where we pour in the brake fluid and it goes down to where it spreads to other lines. That hose has two clamps on either ends of it that keeps it snug to the little inlets that go inside it. I think I spent less than $10 for the length of replacement hose and 2 new clips. I can go out and take photos if you'd like.
 
Troymclure said:
If this is the case, I doubt you are losing fluid. The pedal would be soft, because if fluid can get out, air can get in. Probably just worn pads as others have said
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Now that this is what I'm thinking, that's what it totally feels like.

This is actually a good example of how paranoid a forum like this can make me... naturally, when I feel something off, I assume it's the wor$st po$$ible issue because I've been reading a few horror stories about the pricey master cylinder.

Hopefully it's just simple brake stuff. I'll know for sure on Tuesday. :cheers:
 
Sporin said:
Now that this is what I'm thinking, that's what it totally feels like.

This is actually a good example of how paranoid a forum like this can make me... naturally, when I feel something off, I assume it's the wor$st po$$ible issue because I've been reading a few horror stories about the pricey master cylinder.

Hopefully it's just simple brake stuff. I'll know for sure on Tuesday. :cheers:
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Why would this forum make you "paranoid"? Problems come up. Some of them are cheap fixes and some are expensive. We members try to help other members by speculating on an issue where all that we have to go on, is what you tell us. We try to help you narrow down the possibilities so that you save money and time. Me personally, if I genuinely thought that I had a hydraulic brake leak, somewhere in my system, yes, I would be worried about the potential cost of repair to said leak, upon proper diagnosis. But I certainly would not be "paranoid" from the information given here on T4R.org by members who have more experience than myself on a given issue. I guess what I am saying is don't panic till you know for sure. Take the info you get here and follow up with it as best you can. You can always commit Seppaku (google it) later.
 
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You are reading a negativity into my post that I neither meant or intended.

I love this forum, it's hugely helpful, and I appreciate all the great info given and received.

I was just pointing out that for ME, I occasionally go to the worst possible answer in my mind because of some of the things I read here. That's all.
 
Garage just called and said one of the front calipers is leaking. No other details but I'll take that over the MC any day! :)

I'll find out more when they call back, no idea how it happened.
 
Sporin said:
Garage just called and said one of the front calipers is leaking. No other details but I'll take that over the MC any day! :)

I'll find out more when they call back, no idea how it happened.
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I'm very happy for you. Over time, the seals in the calipers become worn, hard and brittle, and thus, they leak. 15 years ago, you would simply install a "rebuild kit". Nowadays, calipers on the whole are cheap to buy. BTW, I wasn't trying to offend you with my earlier post. I was simply trying to convey the message, do not worry too much about a potential problem until you know for sure as it will usually pan out to be the less expensive issue.... unless, you're like me..... and your evaporator decides to give up the ghost.
 
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Did you notice any increase in the buzzing of your MC pump?....with the leak, i suspect the pump will try to over compensate
 
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