Newbie- basic Q's on me new motor!

[Zoot]

The brake fluid is dot4, do you know when the fluid was last changed?

Hi DanMcG,

looking at my thankfully FSHistory.. December 2021 ( "Platinum service inc brake fluid" in my maintenance program book.. with the brake fluid box ticked/ the most recently this box is ticked).

I see the brake reservoir, & dot4 on the cap. Although I can't discern at what level the fluid is.. these tank vessels are so hard to see.

Thanks Zoot

 

[Zoot]

When you get the "soft" pedal, have you tried pumping the pedal to see if the firmness comes back?

As above, I'd check brake fluid for moisture content and see when it was last changed.
Is your brake fluid level correct or dropped at all? A leak in the system can introduce air.

For me, I'd maybe change brake fluid and bleed the system. Check for any obvious leaks. See if that helps.

I doubt you are imagining it and it does need sorting.

Hi BillyC,

No I hadn't tried that, so infrequently it's done it I kinda missed the boat.

It seems 4-3/4 years ago the fluid was changed.

I can't really tell at what level it's at: is there a trick? The white placcy walls don't really let you distinguish the fluid level easily. Yup it seems to change it is sensible, esp as I have sone dot4.

Any idea how much fluid the system takes?? Ive searched YouTube for clips/ tips on how to do the job, but nothing much there to help tbh.

useful advice- many thanks, Zoot

 

[DanMCGARRETT]

Yeah that needs replacing, brake fluid should be changed every 2 years. It's not an expensive job and its best to replace the fluid, rather than just topping up as there may be air/water in the brake lines which need to be removed.

 

[Zoot]

As above, I would suspect your brake fluid.

Brake fluid is hygroscopic - meaning it absorbs water - and this water lowers it's boiling point, brake systems aren't sealed to the outside air - so over time they absorb water - which is one reason your brake fluid needs changing every couple years.

If your brake fluid boils, it is turning from a liquid to a gas - so you lose the hydraulic brake force and your pedal goes down without the brakes doing much slowing down. As the fluid cools down - its turns back into a liquid and you regain your brake pedal.

This normally would never happen on the road, only happen gradually after some spirited driving/racing/ huge hill descent - to get some serious heat into your brake system. An experienced driver might feel their brake pedal getting a bit 'long' and back off the brakes to let them cool

On these two occasions when this happened to you - would you say you had used the brake a lot/down a big hill?
You could also have some brake binding issue - which is constantly applying the brake - with similar outcome - fluid boiling - made worse by old fluid.
After a drive walk around your car a feel your wheels - do any feel warm/hot?

Hi there SuperV8,

interesting info there thanks indeed.

No I hadn't been using on especially big hill prior to the second occurrence, saying that it is fairly hilly around here tho. I have noticed one front driver side wheel feels hotter -maybe- than others. But could be imagining things/ can hardly give you a firm answer.

So it seems perhaps sensible to drain/ change the fluid. But alas I can't see any convenient YouTube clips as to how.

you know how much dot4 fluid the system contains? That's the 1st Q to ask.

Thanks, Zoot

 

[SRGTD]

Yeah that needs replacing, brake fluid should be changed every 2 years. It's not an expensive job and its best to replace the fluid, rather than just topping up as there may be air/water in the brake lines which need to be removed.

@Zoot - as above. I’d get it done sooner rather than later as you never know when you might need to rely on your brakes in an emergency situation. IMHO brakes and tyres are two of the most important components for keeping safe and staying in control of your car.

 

[nd-photo.nl]

Yes, it needs to be done every other year.

@Zoot you can use a small flashlight on the side of the brake fluid reservoir to check the level.

This is the sequence btw, so not the rear first (!)

Bleeding sequence:
1. Front left brake caliper
2. Front right brake caliper
3. Rear left brake caliper
4. Rear right hand side brake calliper

 

[Zoot]

@nd-photo.nl Grateful for those steps- hopefully I can gain the confidence to do this job.

Ok Ive established my fluid level is up towards max mark (removing the lid, the level is just over the mesh).

So it can't be a case of level not being high enough. So it seems draining & changing the fluid then I guess.

I've seen the basics of how: but was hoping it was similar to oil, ie undo a sump plug thing, drain / refill.. but more complicated involving a pressure tank.

Is this tank just used to force it through to substitute old for new, rather than to set the renewed fluid to some sort of optimal pressure once it's in?

Has anyone done this job themselves?

Thanks, Zoot

 

[SRGTD]

I would say that if you’re not sure how to do a brake fluid change then it’s best left to someone with the knowledge and skills of how to do it.

As @DanMCGARRETT has said, it’s not an expensive job but it’s something that definitely needs to be done correctly.

 

[nd-photo.nl]

I would say that if you’re not sure how to do a brake fluid change then it’s best left to someone with the knowledge and skills of how to do it.

As @DanMCGARRETT has said, it’s not an expensive job but it’s something that definitely needs to be done correctly.

100% this. Don't mess around with brakes if you are unsure, they literally save your life.

I have done the brake fluid on my MK3 for the first time not too long ago, but I bought a pressure bleeder and I have built up quite some experience over the years. Without the pressure bleeder, I would not have done it. For me this is the correct way of doing brake fluid changes

 

[DanMCGARRETT]

Like everyone says brakes are very important plus last thing you want is to get halfway through the job with the car in bits and find a bolt/nut is seized and you cant get it off . I would say a garage would probably want around £50-£60

 

[serdar_18fr]

I have done the brake fluid on my MK3 for the first time not too long ago, but I bought a pressure bleeder and I have built up quite some experience over the years. Without the pressure bleeder, I would not have done it. For me this is the correct way of doing brake fluid changes

A couple of months ago I got calipers of my Cupra Ateca painted. The paint shop guys used the services of a brake shop next to them, to drain the hydraulic fluid and remove the calipers, and then to reinstall, add fluid and bleed the air. They tried to bleed it by the most basic foot pumping technique, four or five times maybe, but couldn't manage to bleed the air completely. At the end, thinking they are incompetent, I had to intervene and get my car back with an abnormally soft brake pedal and drive back home like that. Next day I took it to my Cupra dealer and explained the situation. They have done it correctly using a bleeder machine without a drop of sweat. My takeaway from this is that one should drop the old habits and start using the technology where it's available.

 

[RUM4MO]

If, and only if you do attempt to replace the fluid, you DO NOT drain the system and refill it, what you do is to remove enough fluid at each of the wheel areas, one at a time - and while doing this, checking/maintaining the fluid level in the reservoir.

I find that 1000ml is enough if this job is done every 2 years - if your unsure, always err on the safe side and remove more than less, and so buy more than just 1000ml of DOT4 ESP brake fluid, note "DOT4" as a brake fluid description is not enough, it needs to be "DOT4 Plus" or "DOT4 ESP" or similar names so that you end up with the fluid version that fits the VW Group spec. Note - the fluid versions that I've referred to will cost more than the "old school" basic DOT4.

 

[serdar_18fr]

DO NOT drain the system and refill it, what you do is to remove enough fluid at each of the wheel areas, one at a time

My dealer had a question exactly about that, they asked "why did they (the brake shop in my story above) drain the system? They shouldn't have done that"
Then they explained to me why that is important but I don't remember the details right now.

 

[nd-photo.nl]

If the system is drained completely, additional pre-bleeding is necessary

 

[RUM4MO]

Audi official workshop manual states:- front remove 0.20ltr from each wheel, rear remove 0.30ltr from each wheel, clutch sec cyln remove 0.15ltr.

I like/chose to refine this and remove from the rear wheels first, removing more than the 0.30 to make sure that I've renewed the reservoir fluid AND the connecting long pipework, from the first rear wheel calliper. Doing it this way means completing the task at the front and so nearer the reservoir that needs to end up with either just the correct level of fluid in it - or slightly lower and then getting topped up after the fluid has been replaced.

Always include removing as much fluid from the reservoir as possible prior to starting this task. Also, I believe that one way to dispose of the old fluid is to absorb it completely in sawdust, then double bag it and place it in the "land fill" waste bin.

 

[nd-photo.nl]

Whut? In the Netherlands, we have specialised chemical waste collection points where you can drop off used oil, brake fluid, paint, canisters, etc etc for free