Brake fluid before and after.

stratos

Sorry about the poor photo's.

These are pictures of brand new brake fluid and fluid drained from a 7 year old car. I had noticed on the service interval, brake fluid should be replaced every 2 years. I had never seen any evidence of this being done, despite the car being serviced by a main dealer for the first 4 years.

I had a look at the fluid in the resevoir it looked okay a bit dark maybe. I decided to flush it out anyway. The initial fluid drained out at the calipers was very discoloured with obvious sooty particles in it. the colour change as new fluid reached each caliper was obvious.

The photograph doesn't do justice to how bad the stuff that came out was, even though it looked okay in the resevoir.

I can't say there seemed anything wrong with the brakes and under normal braking they would probably have been fine. Under heavy braking coming down a hill the moisture in the fluid would probably have boiled. The contaminates probably could have caused the abs valves some damage, and corroded various internal parts.

Anyway I hope the photos load okay and aren't too big.

245

Definitely something that gets overlooked. I change the brake fluid in my classics every two years - I've rebuilt one too many calipers and master cylinders to leave things too long and I've seen how brake fluid deteriorates. As far as I know, the 'sooty particles' are little bits of rubber from the seals as they deteriorate over time. I plan to hold onto my daily driver for a while and a brake fluid change will definitely be done when required (when the fluid gets darker).

When I was in my teens, and before I realised that things were open to interpretation, I tried to persuade a service manager to replace the brake fluid in my mother's Austin Metro on schedule and got laughed out of place for my troubles. (The same service manager was subsequently fired along with the sales manager for things that they shouldn't have done, but that's got nothing to do the the topic). Point is that Irish dealers don't always seem to follow the gearbox oil/diff oil/hydraulic fluid changes that are scheduled. I've read elsewhere that UK dealers do scheduled items that Irish ones don't bother with (valve clearance adjustment on the Toyota D4D for example). Much as I hate to undermine troubled Irish dealers, maybe another incentive for travelling up North?

shane55

I'd say there are cars on the road for 15yrs or more with the same brake fluid in them. I asked a mechanic to change mine once and he said it was a bad idea as the procedure could damage a brake cylinder, complete rubbish of course.I changed my own about 2 yrs ago when my megane was 7 yrs old. tbh the old fluid didnt look bad at all but they say that you cant tell by appearance if the fluid is good or bad. the fluid absorbs moisture over time. If the brakes get hot the moisture in the fluid can boil causing brake failure.

tommmy1979

shane55 wrote: »

I'd say there are cars on the road for 15yrs or more with the same brake fluid in them. I asked a mechanic to change mine once and he said it was a bad idea as the procedure could damage a brake cylinder, complete rubbish of course.I changed my own about 2 yrs ago when my megane was 7 yrs old. tbh the old fluid didnt look bad at all but they say that you cant tell by appearance if the fluid is good or bad. the fluid absorbs moisture over time. If the brakes get hot the moisture in the fluid can boil causing brake failure.

It's not complete rubbish actually... it's very easy to damage a shaft seal on the master cylinder while bleeding the brakes on a car that hasn't had it done for many years, should be ok so long as you don't use all the pedal travel when pumping through the new fluid.

T

BrianD3

Thanks for posting the pics but I don't see anything wrong with the old brake fluid, it is normal for brake fluid to go that colour. The colour of the fluid has little or nothing to do with the moisture content. And the moisture content of brake fluid stabilises (at a low level) after a few months in the system. The capacity of brake fluid for absorbing water is greatly exaggerated.

There is no evidence here to suggest that the old brake fluid would would have caused brake failure or that it would have damaged the ABS valves etc. As already stated the "sooty" partices in the fluid are probably bits of rubber from the hoses, you'll find these particles in six month old fluid too. I'm not sure what effect if any these particles have on the brake system or brake performance. But the more often you change your brake fluid the more likely you are to introduce hard particles of grit etc. into the system which I'd imagine are more likely than the rubber particles to damage seals.

Voodoomelon

Two year old brake fluid from a 740i BMW.

stratos

Just to add to my original post. I hadn't driven the car with the new fluid, I have since. I obviously didn't notice the slow degredation of the brake performance. I didn't realise how sloppy the brakes had got.

The brakes now feel much more responsive braking action begins with the first touch of the pedal. The braking now feels much more progressive and with less effort. Definitly worth doing.

Voodoomelon

Absolutely and you don't need two people to do it either, you can do it yourself in about 60-90mins tops, and most of that is getting the wheels off. I use this kit, cheap and very effective: http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_204645_langId_-1_categoryId_165469

My front calipers actually have 2 seperate resevoirs, so there's actually 6 to bleed in total which adds to the time, but as you say, well worth doing.

stratos

I actually have used that gunsun kit, Voodoo I find it very good, though the thoughts of over pressurising the system and blowing a resevoir of brake fluid off the cylinder all over the car always worries me . There was 114,000 miles on mine, what was on the 740 when you changed the fluid. I have driven the car some more since and the brakes are transformed

I have replaced the shocks and steering damper, this along with the fluid change and the old girl is starting to feel like new again.

Voodoomelon

I didn't actually do that change on the 740, one of the lads on the 7 series forum posted it up last week, you can be sure the mileage on it was over 100k.

When I changed mine last year, there was a very noticable difference in the colour of the stuff coming out and the dot4 going in. I must look in the service history to see when it was last done, I seem to recall it was around 45k miles and my change was only at 74k.

Halfrauds

stratos wrote: »

Sorry about the poor photo's.

These are pictures of brand new brake fluid and fluid drained from a 7 year old car. I had noticed on the service interval, brake fluid should be replaced every 2 years. I had never seen any evidence of this being done, despite the car being serviced by a main dealer for the first 4 years.

I had a look at the fluid in the resevoir it looked okay a bit dark maybe. I decided to flush it out anyway. The initial fluid drained out at the calipers was very discoloured with obvious sooty particles in it. the colour change as new fluid reached each caliper was obvious.

The photograph doesn't do justice to how bad the stuff that came out was, even though it looked okay in the resevoir.

I can't say there seemed anything wrong with the brakes and under normal braking they would probably have been fine. Under heavy braking coming down a hill the moisture in the fluid would probably have boiled. The contaminates probably could have caused the abs valves some damage, and corroded various internal parts.

Anyway I hope the photos load okay and aren't too big.

i think your fluid is towards the better end of the scale:), mine was black.:D

stratos

yes i actually took black brake fluid out of a 25 year old car I bought, I reckon it was in there since the car was new. The strange thing is the brakes worked fine. It was like oily guinness.