Topping up brake fluid

Post by **pim123** » Fri Aug 18, 2006 7:42 pm

Hi,
I have got a remote brake fluid kit on my Minor.
The fluid level mark is at the top of the container.
The level of the brake fluid however is much lower now.
Should I fill it up an if so can I use any brake fluid ?

Post by **Kevin** » Fri Aug 18, 2006 8:08 pm

Dot 4 universal brake fluid should be fine as long as its hasn`t got silicon fluid in it but I think that it should have a sticker to say it has got silicon fluid.

Post by **pim123** » Fri Aug 18, 2006 8:15 pm

Thanks Kevin, so Dot 4 without any silicone in it ! (just out of interest..what would the silicone do ?)

Post by **Kevin** » Fri Aug 18, 2006 8:57 pm

Dot 4 brake fluid is completely different to silicon fluid and the 2 must not be mixed.
Silcon is far more expensive and also more difficult to bleed when its first used and cost 4 or 5 times as much however it is not hygroscopic (I hope thats how its spelt) so it does not absorb moisure so its life in the brake system is many times longer and it also removes the corrosion issues that can occur in the brake cylinders when the standard fluid is not changed often enough.
Hopefully Jonathan will see this and give a professional view on the pros and cons of the 2 types.

Post by **bmcecosse** » Fri Aug 18, 2006 10:31 pm

However - be warned - those who have changed to silicone fluid often find the old seals in the system start to leak soon after. So - if doing this - invest in new seals (and probably flexi pipes too) at the same time. Why would it be more difficult to bleed ??

Post by **pim123** » Fri Aug 18, 2006 10:43 pm

I don't know what kind of fluid is in it now, can I safely top it up with Dot4 non silicone fluid though ?

Post by **Kevin** » Sat Aug 19, 2006 12:44 am

if doing this - invest in new seals

But Pim isnt.

Yes Dot 4 brake fluid will be fine as you have no markings to say otherwise, here is an example
http://cgi.ebay.co.uk/UNIPART-BRAKE-CLU ... dZViewItem

Post by **57traveller** » Sat Aug 19, 2006 11:24 am

According to Automec who make DOT5 Silicone brake fluid it is quite safe to mix it with normal DOT4 fluid. However the advantages of a higher boiling point and moisture absorbancy resistance will be lost. The only fluid it can't be mixed with is the mineral based type used in some Citroen and Rolls Royce vehicles, as can't/shouldn't DOT3 and DOT4 "glycol" fluids.
I'd personally be more concerned as to why the reservoir level is "much lower now".

Post by **pim123** » Sat Aug 19, 2006 11:35 am

I didn't mean it's all of a sudden lower as normal, it's just that I have the car for two months now and only now saw that the level was lower than it is supposed to be.

Post by **jonathon** » Sat Aug 19, 2006 2:05 pm

The silicone fluid we have used is quite blue in colour, where as ordinary Dot 4 tends to have a yellow hue. This is our experience and may not apply to all silicone fluid. If in doubt remove a small amount of fluid from the header tank, and put it on some waste painted steel, if it bubbles up the paint then its not silicone, and you can proceed to top up with Dot 4.

Post by **Willie** » Sat Aug 19, 2006 4:31 pm

Pim123, re the lower fluid level. You may have the same problem as me in
that my(plastic) remote reservoir persists in leaking slightly if filled to the top,
I now fill mine to two thirds full and have no problems. I have obviously marked the new level so that I can tell instantly if the level has dropped.

Post by **pim123** » Sat Aug 19, 2006 5:15 pm

Ok , thank you all for your help !