Brake fluid change?

[Steve61]

I’ve owned my Z3 for 6 months now, and I’m enjoying some great motoring now that the summer is here. The car is in great nick with very little to be done, but I’m starting to think about routine servicing stuff.

Looking through the paperwork I have, I reckon the brake fluid was last changed in Sept 2017, and the car has only done about 1,200 miles since then (it was SORN for the two years before I bought it). I was expecting to see a brake fluid clock illuminate on the dash, but I see from searching this forum that the clock stops when the battery is flat, I had to get a new battery when I bought the car.

Question is, do I need to change the brake fluid in view of the low mileage, the fluid level is on max and the brakes seem sharp to me, the car has always been garaged? I was thinking of leaving it until November when the MOT is due and then getting a full service done then.

Although I haven’t picked up a spanner for over 30 years (always had company cars), I’m a competent DIYer and willing to learn and give anything a go. However, it seems to me that once I’ve bought the bits I need (brake bleeding kit etc, and that’s a whole different question), I may as well get a garage to do it?

To change the brake fluid, I’ve been quoted £155 by BMW dealership (includes £30 “source” charge, aka ripoff charge), or £49.50 by local independent BMW specialist (includes labour, parts and VAT).

Seems like a no brainier to me, but would appreciate your thoughts.

 

[mrscalex]

Brake fluid is hygroscopic (absorbs moisture) so that's why it's a time based thing not mileage related. In short if you can't be 100% certain when it was last changed it's best to change it. Same with any service item like coolant, oil, filters and I would also say thermostat & water pump.

I use a pressure bleeder that cost me around £50 from Machine Mart. If you're a competent DIY'er you'll breeze through it. Get a jar, pour in a measured 250ml of water, make a mark on the jar, chuck the water and then draw through on each corner to that mark. In other words you are pushing 1 litre total through the system. Though I tend to keep 2 litres in my pressure bleeder so it doesn't run out. You will end up with too much fluid in the reservoir so get some cheap syringes off ebay to draw a little back off. As well as some clear tubing to go over the bleed nipples. Ring spanner over bleed nipple, tube over bleed nipple, open up 1/4 to 1/2 turn and watch it come through. Tighten up back to the point the spanner started - pointing straight up is only sensible option really

So it's a non brainer to me to DIY. Brake bleeding as well as discs & pads is a very high margin garage line of business for little in the way of effort. The bleeder pays for itself first time out. @t-tony will say to gravity bleed without the expense of the bleeder but I don't have the patience to wait while it does that!

Your only potential challenge really is if the bleed valves are stuck - they sometimes are, particularly on the rear. They can sometimes be seized enough the only fix is a replacement caliper. But this only really tends to be on cars that haven't had the fluid changed for years. I doubt that will be the case if yours was done in 2017.

 

[t-tony]

I have a pressure bleeder, but for those who don’t, gravity will do the job for you.

Tony.

 

[DomiMik]

That's a very detailed description, everything one needs to know @mrscalex
Steve, for the quoted 155£ you can buy a quality brake bleeder and plenty of brake fluid for the next decade, definitely would recommend DIY. BMW says a change is necessary every two years, if you're unsure you can as well buy a brake fluid tester for little money:

Universal Brake Fluid Tester, Portable Precision Brake Oil Quality Control Digital Test Pen, Auto Vehicle Automotive Diagnostic Test Tool : Amazon.co.uk: Automotive

Buy Universal Brake Fluid Tester, Portable Precision Brake Oil Quality Control Digital Test Pen, Auto Vehicle Automotive Diagnostic Test Tool at Amazon UK. Free delivery on eligible orders.

www.amazon.co.uk

Tony, I didn't know it's possible to gravity bleed the brake system, I'll have to look into that.

Regards
Dominik

 

[colb]

Be aware should you let the level in the reservoir drop too low and air is allowed to enter the system, if this happens you will need Inpa software to cycle the abs pump to ensure any air is expelled in the lines by bleeding each calliper. Start at rear near side followed by offside rear then front near side then front offside. Cycling the abs with Inpa as you bleed each calliper will ensure no air is left in the lines.

 

[mrscalex]

Be aware should you let the level in the reservoir drop too low and air is allowed to enter the system, if this happens you will need Inpa software to cycle the abs pump to ensure any air is expelled in the lines by bleeding each calliper. Start at rear near side followed by offside rear then front near side then front offside. Cycling the abs with Inpa as you bleed each calliper will ensure no air is left in the lines.

That's why I keep 2 litres in the pressure bleeder and make sure I draw off exactly 250ml. Never needed to use INPA yet.

 

[Steve61]

Thanks for the very informative replies, I will def give it a go. Think I will get one of those brake fluid testers, I can see that being useful.

 

[mrscalex]

Thanks for the very informative replies, I will def give it a go. Think I will get one of those brake fluid testers, I can see that being useful.

I have one but I’m a little anti. They are cheap and not sure how reliable. But main thing is if it’s due it’s due. If you’re not sure on history it’s also due

 

[Steve61]

I have one but I’m a little anti. They are cheap and not sure how reliable. But main thing is if it’s due it’s due. If you’re not sure on history it’s also due

Fair enough, good point made.

 

[motco]

I have avoided replacing a calliper a few times by bleeding from the hose union. It's messy and must be done with a pressure bleeder or you risk getting air drawn in. Pressurise the system and then crack the hose union until fluid comes out. When the fluid is clear rather than obviously old tighten the union again and try the pedal. If you're lucky it will be firm and you've succeeded. The worst that can happen is you get a little air in and you'll know from the feel. Admittedly I have not done this on a car with ABS and/or DSC - it was on my Westfield - but unless you get a load of air in it shouldn't be a problem.

 

[IainP]

You can also use a vacuum bleeder, £15-20 quid.

2 things to note.
Remove the little green damper pot and top right to the brim with fluid. Do this before bleeding each corner.

You will draw air through the threads of the bleed nipple. To prevent that, smear some SILICONE grease round the top of the nipple. Do not use any other type of grease.

When finished do remember to put the damper pot back in and top the level off.

 

[Andyboy]

I use a Gunsons easibleed, £20 from Halfords. It runs off spare tyre pressure.

Bleed screws can be a sod to undo and what you may find is that the screw thread is a bit loose (particularly on recon calipers) and air can be drawn back in - so with the pressure bleeder in action, close the screws. A bit of grease around the threads helps.

It's also worth bleeding the clutch. The old fluid will be disgusting.