Brake Fluid Replacement Interval

PiKe

PiKe

PiKe

Caporegime
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Had Ford ring up and arrange a service then ask if I wanted my brake fluid changing as it's recommended that it is every 2 years, reasons given were that the brake fluid helps cool the brakes, the callipers and discs but carrying heat away and over time it gets water in it which has a much lower boiling point.

While the explanation sounded good, I'm a bit sceptical, isn't the brake system non-circulative and therefore unable to transport heat? How is water going to get in if the reservoir is never opened?
 
Brake fluid has nothing to do with cooling the brakes, since the brakes arn't a sealed system air can get in, brake fluid is hygroscopic so will absorb water, if you overheat the fluid and get water into the lines then the brakes will go spongy.

However it is worth changing the fluid every few years.
 
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Depends on the car and fluid used really, should say on the service charts from ford, they should be on the internet.

I'd say every 3 years and 36k but i change mine every 2 and 24k.
 
PiKe said:
While the explanation sounded good, I'm a bit sceptical, isn't the brake system non-circulative and therefore unable to transport heat? How is water going to get in if the reservoir is never opened?
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It has to breathe otherwise you'd get some serious pad knock back when they started to wear and you needed to displace 3mm of piston with hydraulic fluid before your brakes started to work. This is how water gets in the system.
 
No-one has ever been able to tell me why one would ever bother replacing brake fluid as long as the brakes still "feel" ok?
 
The brakes can still feel ok but it can speed up the corrosion of the lines having old fluid in, or so i've heard, or the brakes can feel ok but the fluid will have more water content than it should, until you put real heat into the brakes you wouldn't know the difference.
 
Jez said:
No-one has ever been able to tell me why one would ever bother replacing brake fluid as long as the brakes still "feel" ok?
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Boiling point gets lower as it ages/gets wetter.

Cold brakes may well feel okay, however once they get to their limit and the boiling introduces air bubbles into the fluid your braking effort/travel will go up massively to apply the same clamping force at the caliper. Eventually that you would end up using the full range of the master cylinder stroke and still not brake aswell as you demand. The has a knock on effect of pushing a 'conditioned' master cylinder seal onto a 'virgin' part of the cylinder and can end up needing a cylinder rebuild aswell.
 
Ford offered me exactly the same when my car was in for a service last year. Bit wary as I thought they were just after a bit of extra business but I had it done anyway and was surpised how sharper the brakes were when I got it back. I think it was just under £40.
 
Jez said:
No-one has ever been able to tell me why one would ever bother replacing brake fluid as long as the brakes still "feel" ok?
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Its because of corrosion. Changing the fluid every two years means the fluid never has a chance of building up water. Ive had brake fluid in for years and years before and the brakes still felt fine but nearly every manufacturer recommends two yearly fluid changes.
 
Dandle said:
Its because of corrosion. Changing the fluid every two years means the fluid never has a chance of building up water. Ive had brake fluid in for years and years before and the brakes still felt fine but nearly every manufacturer recommends two yearly fluid changes.
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Unless you have silicone Dot 5.0 brake fluid, corrosion isnt really the issue.
 
Ford have a service schedule of every 2 years for their brake fluid, changed mine the other day, doesnt feel massively different but bit of peace of mind knowing that it is fresh in there.
 
Every two years and/or whenever I was doing the disc's when it was me doing it. Every two years when it's the dealer. It's not expensive (similar cost for a coolant change) but it's worth doing.
 
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