Good Sam Club Open Roads Forum: Tech Issues: Brake fluid change?
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 > Brake fluid change?

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opnspaces

San Diego Ca

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Posted: 10/27/19 10:08pm Link  |  Quote  |  Print  |  Notify Moderator

DFord wrote:

Doug, you mean to say you've never heard of someone riding their bakes a little too much going down a mountain and heated them up so much it cause the water in the brake fluid to boil which made the brakes useless?


I have definitely heard about riding the brakes really heavy doing down a grade can cause brake failure. But I have never heard that it was attributed to water turning to steam in the fluid.

Riding the brakes heavy and boiling the water in the fluid will put a gas in the fluid which will cause a spongy brake pedal. The brakes will still work, but you have to press harder or maybe pump the pedal a few times.

Kind of off topic but still relevant is that the real problem with riding the brakes too hard is brake fade. The action of braking converts momentum into heat which transfers into the rotor, caliper, bearings etc. When the brakes get too hot there is no heat transfer possible, also the pads will start to outgass between the pads and the rotors further reducing any friction. At this point you will still have a good pedal feel, but the vehicle just does not slow down. This is one of the reasons you see slotted or drilled brake rotors on race cars. The slots or holes give the gasses a way to escape from between the two surfaces. Of course like most things in life there's no such thing as a free lunch. Yes drilled and slotted rotors allow the brakes to get hotter in extreme circumstances and still work. The flip side to this is there is less surface contact with the pads so the brakes are not as strong. So on a race car they can engineer in larger brakes. On your production vehicle you're pretty much stuck with the size the manufacturer engineered.


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DFord

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Posted: 10/27/19 10:21pm Link  |  Quote  |  Print  |  Notify Moderator

Moisture from your brake fluid can cause failure


Don Ford
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opnspaces

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Posted: 10/28/19 04:11am Link  |  Quote  |  Print  |  Notify Moderator

I can find just as many articles to support my statement, but in the end all it's going to do is derail the topic. It's your wallet, spend your money as you see fit.

Heat causes brake fade moisture causes spongy pedal

otrfun

Desert SW

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Posted: 11/05/19 08:00am Link  |  Quote  |  Print  |  Notify Moderator

dougrainer wrote:

otrfun wrote:

We siphon (with a vacuum brake bleeder) all the brake fluid out of the reservoir every year or two on all our vehicles, then refill it with new synthetic brake fluid. Takes about 12-16 oz. to refill the cars and 32 oz. for our Ram 3500. Literally takes all of 2-3 minutes to do. Can't say there's some dramatic improvement in braking, but it's nice to see the fluid clear with so little effort and cost. Still do the occasional brake bleed. When we do, the brake fluid is significantly clearer vs. how it normally looks when we don't do the siphon and fill.
This does NOT make any sense. What about the fluid in your Lines and calipers that is OLD? If you do anything it would be to flush and bleed the complete system. Not the occasional bleed. Doug
You missed the point. What I'm doing is the very same thing as a drain and fill on most automatic transmissions. In a drain and fill you only remove, say, 50% of the tranny fluid. Removing 50% of the old fluid (or 50% of the old brake fluid) is still a significant improvement over doing absolutely nothing. Also, keep in mind this brake fluid siphon/drain and fill only takes 2-3 minutes. We typically do it once a year. It's above and beyond what the manufacturer requires, so it's a good thing and no harm done. Lastly, we still do a complete brake bleed. When we do the total brake bleed it's hard not to notice the fluid is much clearer than if we hadn't done the brake fluid drain/siphon and fill. Bottom line, we've found a brake fluid reservoir siphon/drain and fill well worth 2-3 minutes of our time. As always, YMMV.

T18skyguy

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Posted: 11/05/19 10:10am Link  |  Quote  |  Print  |  Notify Moderator

DFord wrote:

Doug, you mean to say you've never heard of someone riding their bakes a little too much going down a mountain and heated them up so much it cause the water in the brake fluid to boil which made the brakes useless? I've heard those stories for years. Around where I live with heavy dew the normal every morning thing, my brake fluid turns dark as it absorbs moisture pretty rapidly. I should change it yearly but I'm not that good at keeping up with it and I don't have any trips over the mountains planned - plus I come down mountains as slow as I go up them. Yes, brake fluid has an affinity for moisture and fluid reservoirs are not air tight so there's no way to prevent it from becoming contaminated unless you move to a very low humidity area in the dessert.

I know a guy who lost all braking on a National Sea Breeze coming down Siskiyou pass. They would have been killed, but he was able to get into low gear and to use the emergency brake to get it stopped. After he let it cool for an hour it was totally back to normal. When the caliper's get over boiling point, the water in the brake fluid forms a steam bubble, which does not work in the caliper. The other issue with water in the lines is it corrodes the interior of the lines and calipers. These rust particles then cause the caliper piston to stick. I'm the first to admit I let mine go too long, but I recently got a pressure bleeder that makes it a lot easier.


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ppine

Northern Nevada

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Posted: 11/06/19 08:37am Link  |  Quote  |  Print  |  Notify Moderator

My mechanic always says it is not necessary.

mapguy

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Posted: 11/08/19 05:51pm Link  |  Quote  |  Print  |  Notify Moderator

Surprising the response here regarding the operational safety aspect in regards to brake system maintenance. When brake fluid fails -it gives no warning at all - one push on the brake pedal it works and the next push the pedal drops to the floor.

No matter what has been posted here -brake fluid does need to be changed on modern vehicles, too. Operating environment has a great impact on the life time of brake fluid. Brake fluid life is longer in areas of low humidity and or low moisture. Example the desert SW.

Tow vehicles subject the brake fluid to much higher heat and longer use cycles than a grocery getting vehicle.

ABS components fail from contaminated (dirt/moisture) fluid easily. Price out these components - it is much cheaper to flush the fluid periodically.

JimK-NY

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Posted: 11/09/19 07:44am Link  |  Quote  |  Print  |  Notify Moderator

Would you send an email along with documentation to the Dodge Ram technical people? They did not include that recommendation.

Gjac

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Posted: 11/09/19 02:00pm Link  |  Quote  |  Print  |  Notify Moderator

I don't know how many on here remember honing the wheel cylinders for drum brakes back in the 60's with a honing tool inserted into an electric drill. When you removed the rubber ends and run your fingernail inside the cylinder you could feel where the ID of the steel had been etched away from the moisture. The depth of etched valleys were deep enough to cause the rubber seal to leak brake fluid all over the brakes, which to me is serious for a 20-30k lb MH coming down a steep hill. I don't change mine every 2 years, I have a Chevy chassis but have changed it probably 3-4 times over the last 15 years. What I do is jack up the front end and gravity drain the fluid starting in the rear the working my way to the front. I suck out the old fluid from the MC first with a turkey baster and add new fluid so only the lines have old fluid. When the fluid comes out clean I close the bleeder and open the next one. I can do this job myself and it does not take as long as it sounds.

ktmrfs

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Posted: 11/09/19 09:51pm Link  |  Quote  |  Print  |  Notify Moderator

Gjac wrote:

I don't know how many on here remember honing the wheel cylinders for drum brakes back in the 60's with a honing tool inserted into an electric drill. When you removed the rubber ends and run your fingernail inside the cylinder you could feel where the ID of the steel had been etched away from the moisture. The depth of etched valleys were deep enough to cause the rubber seal to leak brake fluid all over the brakes, which to me is serious for a 20-30k lb MH coming down a steep hill. I don't change mine every 2 years, I have a Chevy chassis but have changed it probably 3-4 times over the last 15 years. What I do is jack up the front end and gravity drain the fluid starting in the rear the working my way to the front. I suck out the old fluid from the MC first with a turkey baster and add new fluid so only the lines have old fluid. When the fluid comes out clean I close the bleeder and open the next one. I can do this job myself and it does not take as long as it sounds.


never honed a brake cylinder on drum brakes but did need to replace a few even though I flushed the brakes every year or so.

Today, gone are drum brakes, gone are the days when car brakes could do ONE panic stop from about 60mph before fade set in. So... now brakes have more reserve, doesn't mean moisture doesn't affect them, just means it doesn't show up as quick but the failure is the same when it happens from water in the fluid.

Water molecules are very small, you can make things "air tight" so that Nitrogen or Oxygen molecules won't go through but that doesn't mean they are "water tight" H2O molecules are much smaller. Water vapor can migrate through many plastics and rubber hoses and contaminate the brake fluid.


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