brake fluid flush

texasfan88 · Nov 14, 2019

Hi,

A couple of weeks ago, I had my oil changed in my truck and they recommended a brake fluid flush. Being someone who has never had this service done before, I decided to get a few different opinions from different mechanics and one of them said not to change it until you reach about 100,000 miles or if you're getting new brakes. I've had my truck for 2 years now and it currently has 50,000 miles on it. Is it normal to change the fluid at this mileage interval or do you just go by the 2 year mark, regardless of the mileage? I purchased a brake fluid tester for less than $10 from Amazon and it registered between 3%-4% water content, which is not good. I'm curious to know just how accurate those meters are though. Should I change the fluid now and get it out of the way or wait like that one mechanic told me? The last thing I want to to do is wait too long and have brake failure but I also don't want to spend money, about $100 or so, on a service if I don't need it at this time. My brakes are showing absolutely no sign of decreased performance. I'm experiencing no changes in stopping distance, no vibration and no squeaking unless the brakes are just wet, which is completely normal. Anyway, any help would be appreciated.

chrisbh17 · Nov 14, 2019

Ive done it both ways on many of my vehicles. Some I waited and waited and waited. Some I did after 2 or 3 years.

I didnt feel unsafe in ANY of them, regardless how old the fluid was. BUT what I did notice was, after getting around to changing the fluid, you could FEEL a braking difference in the pedal. So, to me, the deterioration of the fluid quality was so gradual over time that you never really noticed it until you were on brand new fluid again.

Personally, I would go every 2 or 3 years. It could be slightly variable, based on driving conditions (lots of stop and go means lots of heat cycling brakes and fluid), weather conditions (hot to cold and vice versa will increase possiblity of condensation), etc. But Im not sure I would go 100K miles, no matter how fast I could put 100K miles on my vehicle.

I would also change the fluid out whenever changing the pads and/or calipers and Im not quite sure I could get 100K on ANYTHING without having to change the pads at least once.

If you are doing it yourself, look at a Motive Power Bleeder setup. Not overly expensive and makes the job a lot easier than the old pump pump pump, close bleeder, etc.

KeepRight · Nov 14, 2019

texasfan88 said:
Hi,

A couple of weeks ago, I had my oil changed in my truck and they recommended a brake fluid flush. Being someone who has never had this service done before, I decided to get a few different opinions from different mechanics and one of them said not to change it until you reach about 100,000 miles or if you're getting new brakes. I've had my truck for 2 years now and it currently has 50,000 miles on it. Is it normal to change the fluid at this mileage interval or do you just go by the 2 year mark, regardless of the mileage? I purchased a brake fluid tester for less than $10 from Amazon and it registered between 3%-4% water content, which is not good. I'm curious to know just how accurate those meters are though. Should I change the fluid now and get it out of the way or wait like that one mechanic told me? The last thing I want to to do is wait too long and have brake failure but I also don't want to spend money, about $100 or so, on a service if I don't need it at this time. My brakes are showing absolutely no sign of decreased performance. I'm experiencing no changes in stopping distance, no vibration and no squeaking unless the brakes are just wet, which is completely normal. Anyway, any help would be appreciated.

Listen to the others... Here's my opinion...

Will it hurt to flush the brake fluid - nope, well other than your money.

Does it need flushed, OK, 100k, sure. Unless really dirty,... Check owner manual.

The same applies to, power steering fluid, rear, front (4x4) diff lube. Unless you have VERY LOUD noises - wait until over 100k. Then it's just a matter of your money. Not changing those fluids, your truck won't fall apart.

Obviously, when you do change the fluids - use the best quality fluid / lube / filters that you can afford.

Honestly, you've got nothing to worry about.

I really hope this helps.

texasfan88 · Nov 14, 2019

Thanks. I might just suck it up and get it done now and get it out of the way. One very important thing I forgot to mention is that I have hosed down my engine bay a couple of times because there was mud all over the place and that is probably the reason for why the moisture level is so high at this point. I figured it's probably best to spend the $100 to get the service done and know that I'm maintaining the truck properly, than wait too long and have something major go wrong. However I will look into one of those power bleeders. Amazon is selling them for under $40 which is not bad at all.

texasfan88 · Nov 14, 2019

KeepRight said:
Listen to the others... Here's my opinion...

Will it hurt to flush the brake fluid - nope, well other than your money.

Does it need flushed, OK, 100k, sure. Unless really dirty,... Check owner manual.

The same applies to, power steering fluid, rear, front (4x4) diff lube. Unless you have VERY LOUD noises - wait until over 100k. Then it's just a matter of your money. Not changing those fluids, your truck won't fall apart.

Obviously, when you do change the fluids - use the best quality fluid / lube / filters that you can afford.

Honestly, you've got nothing to worry about.

I really hope this helps.

I don't think there is a maintenance interval for brake fluid in my owner's manual but I can check to be sure. I know there isn't one for transmission fluid but ZF says to change it every 50,000-75,000 miles, depending on how you use the vehicle.

Hemi395 · Nov 14, 2019

Brake fluid absorbs moisture and gets acidic after several years. I flush mine every 2-3 years depending on how dark it is. Brake fluid is cheap compared to abs modules, brake boosters, etc.

Get yourself one of these and flushing brake fluid will take you 25 mins by yourself:

Motive Products 0103 Power Bleeder Fits Late Model Chrysler Vehicles https://www.amazon.com/dp/B000TYJEXG/ref=cm_sw_r_cp_apap_VMVeWMhJwqLj5

Burla · Nov 14, 2019

Flushing is easy, you just need the finger wrench for the brake line, needle nose pliers as a second thing, and I have a brake bleeder, but I chose to use a bottle method. You need the 32 ounces size to do it right. There is a huge difference between expensive brake fluids and the cheap stuff you get at autozone. The cheap stuff is ok if used every 2 years and you don't get the brakes hot, but I posted a graph that shows wet boil temps. I brake fluid like redline boils at 400f where something you get off shelf boils 300f. And the main reason that is a benefit is when the fluid gets old and contaminants come on. You can go longer if you use that type pf fluid versus cheap stuff. It doesn't have to be redline, any of these with boil temps 400f are good quality base oils, redline mirrors motul. Dot 4.

Burla · Nov 14, 2019

The main thing you need to remember is everytime you press the brake pedal to flush 3 times, you have to refill the master cylinder. If you get air in the system, you have to start process over. I did this twice last couple months on friends car and wife's, easy as pie. Helps if you have a buddy holding bottle at the wheel as you pump brakes and add fluid to master cylinder. Pay attention to do the farthest line from master cylinder order and don't forget to tighten brake line when taking hose off. You don't even need to take tires off.

Elevated 2013 · Nov 14, 2019

So, I’m old school when it comes to brake fluid and it’s also how I was trained when I went to school. I never flush my brake fluid unless I’m replacing a part that requires me to open the lines like a caliper, master cylinder, brake hose, or brake line. The system is a sealed system and should never have any contaminants in it. The fluid does get old. That is a fact. But I’ve had cars with more than 100k miles and never had the fluid changed and stopped fine even after long periods of stop and go traffic. I’m not saying the others are wrong in any way. But that was how I was trained and that’s how I’ve always been since I started working on cars professionally.

If you decide to do it yourself, make sure to get a line wrench and not just an ordinary wrench to open and close the bleeders. You will be less likely to strips them when you first open them. They look almost like a normal wrench but the open end of the wrench actually closes more and is shaped almost in the shape of a nut or bolt head and they are 6 point.

Burla · Nov 14, 2019

Brake fluid is contaminated from piston usage, no way out of it. The piston is open, as in it gets dirt on it, over time it gets dirty and moisture attacks boiling point, so if you have a higher starting boiling point, it is effected less by moisture. My friends truck had no issues that we replaced except brake pads, his oil was black.

daveray9 · Nov 14, 2019

Hemi395 said:
Brake fluid absorbs moisture and gets acidic after several years. I flush mine every 2-3 years depending on how dark it is. Brake fluid is cheap compared to abs modules, brake boosters, etc.

Get yourself one of these and flushing brake fluid will take you 25 mins by yourself:

Motive Products 0103 Power Bleeder Fits Late Model Chrysler Vehicles https://www.amazon.com/dp/B000TYJEXG/ref=cm_sw_r_cp_apap_VMVeWMhJwqLj5

+1 on this. I used this per Hemi395's recommendation and it was a breeze. Makes a MityVac seem like a PITA.

RoadRamblerNJ · Nov 15, 2019

Burla said:
The main thing you need to remember is everytime you press the brake pedal to flush 3 times, you have to refill the master cylinder. If you get air in the system, you have to start process over. I did this twice last couple months on friends car and wife's, easy as pie. Helps if you have a buddy holding bottle at the wheel as you pump brakes and add fluid to master cylinder. Pay attention to do the farthest line from master cylinder order and don't forget to tighten brake line when taking hose off. You don't even need to take tires off.

Been doing it this way for 40 years without any problems. Just gotta get your wife out there. That sounds something like this...

Me: Pump it up
Her: OK
Me: Hold it down
Her: OK
Me: Pump it up
Her: Again?
Me: Yes, again. Until I don't say it any more.
Her: OK
Me: Pump it up
Her: I am
Me: pump it 3 or 4 times, I'll stop you.
Her: Should I hold it down now?
Me: Didn't you just pump it up?
Her: Yeah
Me: Then Hold it the **** down!
Her: Now?
Me: JESUS H. CHRIST WOMAN!!
Her: Why do you have to curse?

Take it to a shop dude. It ain't worth it.

RoadRamblerNJ · Nov 15, 2019

Burla said:
Brake fluid is contaminated from piston usage, no way out of it. The piston is open, as in it gets dirt on it, over time it gets dirty and moisture attacks boiling point, so if you have a higher starting boiling point, it is effected less by moisture. My friends truck had no issues that we replaced except brake pads, his oil was black.

My rig calls for DOT-3 but you can also safely fill the drained and flushed system with DOT-4. DOT-4 has a higher boiling point which could be helpful if you do some spirited driving or towing up & down hills.
I know it's not "necessary" but, I completely drain and flush all my lines when I do the pads & rotors. Haven't had to do my '17 2500 (27k mi.) yet but I drove the wheels off my 1500. A set of pads & rotors lasted about 30k miles (roughly once a year). Brake fluid is cheap enough. I did the labor so, materials cost was low.
I slept better knowing it was done.
Also....Do NOT use DOT-5! That is silicon based and you will be screwed if you mix that into any system that calls for DOT-3 or DOT-4.

RoadRamblerNJ · Nov 15, 2019

And yes, buy a line wrench. You WILL round over a bleeder without one. No fun there.

texasfan88 · Nov 15, 2019

Thanks for all the responses, guys. Going to try to get it done this weekend.

Wild one · Nov 15, 2019

RoadRamblerNJ said:
And yes, buy a line wrench. You WILL round over a bleeder without one. No fun there.

I've never used a line wrench on a bleeder screw ,the "box" end of an open and boxed wrench fits pretty well every bleeder screw I've ever ran into,and grabs all sides of the hex on the bleeder screw.Why spend money on a line wrench that isn't as good as the box end of a standard wrench. Line wrenches are meant to be used where you have a line in the way of the nut,have yet to run into a bleeder screw that has a line in the way,lol.If anything you'll round the bleeder screw off if using a line wrench

DodgeDude99 · Nov 15, 2019

Though the difference between a box wrench & a line wrench, a box wrench tends to be 12 point, where a line wrench is 6 point.

You’ll round something out with a 12 point.

Wild one · Nov 15, 2019

DodgeDude99 said:
Though the difference between a box wrench & a line wrench, a box wrench tends to be 12 point, where a line wrench is 6 point.

You’ll round something out with a 12 point.

Never had that happen yet,and i'm 59 years old,a line wrench will expand and slip more often then not on something that has rusted in place,like a bleeder screw will do.If you're rounding them off with a 12 point box end,use a 6 point socket to break the bleeder screw loose first.Line wrenches aren't meant for bleeder screws,sure they can be used,but they're not the ideal wrench to use on a rusty bleeder screw that's frozen in place.

chrisbh17 · Nov 15, 2019

If its rusted, I will hit the bleeder screw with a small detailing size brush, either brass or steel depending on how bad.

Then use a 6 point box wrench to start it (without a hose connected to it to catch fluid), then once its started Ill put the hose on and continue loosening.

Line wrenches are probably more helpful on the connections where the lines go from metal to rubber. If any part of the connection has rust on it, it will tend to twist the metal line which will collapse it ("best" case) or snap it ("worst" case). You almost need 2 line wrenches, 1 for each side of that connection.

68PowerWagon · Nov 15, 2019

RoadRamblerNJ said:
Been doing it this way for 40 years without any problems. Just gotta get your wife out there. That sounds something like this...

Me: Pump it up
Her: OK
Me: Hold it down
Her: OK
Me: Pump it up
Her: Again?
Me: Yes, again. Until I don't say it any more.
Her: OK
Me: Pump it up
Her: I am
Me: pump it 3 or 4 times, I'll stop you.
Her: Should I hold it down now?
Me: Didn't you just pump it up?
Her: Yeah
Me: Then Hold it the **** down!
Her: Now?
Me: JESUS H. CHRIST WOMAN!!
Her: Why do you have to curse?

Take it to a shop dude. It ain't worth it.

OMG!!! I am having flash backs!

brake fluid flush

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