Castrol Response Super DOT 4 brake fluid
#61
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A few pages back the question was raised as to how moisture gets into a sealed brake system. Well it turns out that brake systems are sealed against brake fluid leakage ---- not moisture absorption.
I know this because I have a brake fluid removal and replacement device that pressurizes the brake system to 4 to 10 psi at the fluid reservoir cap. Exceed that pressure and you will hear air escaping around the seams of the reservoir.
It therefore follows that air that can get out can also get in, given the propensity of brake fluid to absorb moisture in the reservoir and also around the seals in the brake pistons.
Ergo, modern brake fluids don't absorb moisture as much as the older formulations.
I know this because I have a brake fluid removal and replacement device that pressurizes the brake system to 4 to 10 psi at the fluid reservoir cap. Exceed that pressure and you will hear air escaping around the seams of the reservoir.
It therefore follows that air that can get out can also get in, given the propensity of brake fluid to absorb moisture in the reservoir and also around the seals in the brake pistons.
Ergo, modern brake fluids don't absorb moisture as much as the older formulations.
#62
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#63
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So your point is that the brake system is sealed air tight? Pray tell where the water/moisture comes from and why all this palaver about water getting in the brake fluid?
The fact is, that at any pressure, air molecules are smaller than whatever molecules make up the brake fluid and they find their way into the system past seals on the pistons and master reservoir that are not air tight.
Just trying to shed some light on the subject, your cute rejoinder re air pressure not withstanding.
The fact is, that at any pressure, air molecules are smaller than whatever molecules make up the brake fluid and they find their way into the system past seals on the pistons and master reservoir that are not air tight.
Just trying to shed some light on the subject, your cute rejoinder re air pressure not withstanding.
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Last edited by user 2029223; 12-19-2011 at 01:28 PM.
#64
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#65
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Forgive me for playing word police but it is hygroscopic.
Also: The size of air molecules matters not. It is the size of water molecules which are much smaller than air and are carried between the air molecules. The main source of moisture is from taking the cap off. Any other source is negligible. That's why most systems have a sight glass. Don't take off the cap unless you are going to top off.
Don't buy a large bottle to top off. As soon as you break the seal it will become contaminated. I keep a very small bottle and discard the remainder as soon as I use it.
One other trick is to use nitrogen to displace the air in the bottle if you have it available. Or the Gas in your TIG welder.
Eddie 04 VDP
Also: The size of air molecules matters not. It is the size of water molecules which are much smaller than air and are carried between the air molecules. The main source of moisture is from taking the cap off. Any other source is negligible. That's why most systems have a sight glass. Don't take off the cap unless you are going to top off.
Don't buy a large bottle to top off. As soon as you break the seal it will become contaminated. I keep a very small bottle and discard the remainder as soon as I use it.
One other trick is to use nitrogen to displace the air in the bottle if you have it available. Or the Gas in your TIG welder.
Eddie 04 VDP
Last edited by MK 82; 12-19-2011 at 07:35 PM.
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#66
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Spoke with an ASE tech today who told me the fluid Jaguar uses is of a synthetic formulation that is not as hygroscopic as regular fluid and therefore has a longer lifespan. He also confirmed the systems are not as "sealed" as one might think and moisture can get in through the filler cap.
#68
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Examples of neglect I have found:
No lining on brake pads
No brake fluid in the reservoir
No engine oil on dipstick
Squirrel or rat's nest in the engine bay
Rats nest in the air cleaner.
Dead cat in the engine bay.
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#69
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Spoke with an ASE tech today who told me the fluid Jaguar uses is of a synthetic formulation that is not as hygroscopic as regular fluid and therefore has a longer lifespan. He also confirmed the systems are not as "sealed" as one might think and moisture can get in through the filler cap.
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#70
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Spoke with an ASE tech today who told me the fluid Jaguar uses is of a synthetic formulation that is not as hygroscopic as regular fluid and therefore has a longer lifespan. He also confirmed the systems are not as "sealed" as one might think and moisture can get in through the filler cap.
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