My 2013 XJ is due for a brake fluid flush and I thought I can do this and save a couple of $. I have a manual-pump fluid extractor which I use for oil changes and it comes with a tube sized for brake bleeder valves. Are there any gotcha's doing this I should be aware of? The Youtube videos look pretty simple. Your advice would be appreciated.
Tom

 

kernt,

You are correct, there is nothing difficult with this job. When I did mine, I used a power bleeder and my code reader. The reader (iCarsoft) opens the valves (in turn) in the ABS unit so you are not forcing and crud past the valve. I know of folks that have done the job without using a reader, but it does make the job easier and faster.

wombat

 

kernt, keep fluid in the reservior and you are good. You lose level, life becomes much more difficult getting all the air out of the system..

 

Thermo,

So true! Been there, done that...not on this car thank Lady Godiva. One advantage, other than just opening the ABS valves, of using the scan-tool is that it runs the ABS pump for (4? secs) each time you select that particular wheel. This means that you don't need help from somebody pumping the brakes. The pressure/power bleed means it's a 45 min job at most....Most of that is jacking and getting the wheels off.

P.S. Because I'm paranoid of getting brake fluid on my paint, I used 10+ sets of gloves.

wombat

 

Thanks for your help guys.

 

Hey Kernt!

I'm looking at the service guide by Jaguar and it's not a regular maintenance item. Did someone tell you that you needed to do this? I'm only curious because I hate with a passion when I have customers tell me they were told they need Coolant flushes, transmission fluid flushes, brake fluid flushes etc "because the guys at Jiffy Lube recommended it". I always tell my customers to check the owners manual for recommended services and if it's not there its because the engineers who built the car do not recommend servicing it.

 

Sabrinaservicewriter, FYI, My "Passport to Service" service guide and maintenance schedule that came with my 2014 XJ 3.0L SC clearly says replace brake fluid every 3 years regardless of mileage.... And I'm overdue.
Check Publication Part No. JJM 18 11 99 142

 

It's good for most cars. Coolant, eh...power steering...eh...Brake fluid is hydroscopic so it should be replaced semi-regularly.

 

The JLR service schedules have included three yearly brake fluid changes for some time. Here is an example from the US Passport to Service for the 2013 X351 but I could have used any recent model. My X150 and F-Pace include the same change interval recommendation:





Graham

 

Change the brake fluid after 3 years!! The fluid work propably Ok in normal traffic even after that time, but on that one time when you are cruising in highway speeds and you need to make an emergency stop, you might have pedal to the metal experience. The brake fluid are hydrostatic, in other word it suck moisture from air. The water in brake systems start to boil in high temp and as we all know you can sqeese gas. In case of water boiling in brakecaliber when you want to brake, you sqeese gas instead of operating brakes. -> Pedal will hit the floor.
(the racing brake fluid are even more hydrostatic what i have learned thru my wallet. These tirewalls around racetracks are very good idea, beed tested them several times...)

 

Sabrinaservicewriter,
My mechanic, a factory-trained Jaguar technician, advised that the brake fluid be replaced at the next scheduled maintenance. As the fluid absorbs water I believe it darkens in color indicating braking efficiency is reduced as the water content increases. Also, the flush is a scheduled maintenance item every 3 years. Thanks for looking out for my wallet though.

~ Thomas

 

Just out of curiosity, how does air and humidity i.e. water find it's way into the brake system. Isn't the master cylinder sealed like it was in by gone days when we never had to change the brake fluid? What is open to the air? Was the old brake fluid non hydroscopic? Got my old guy curiosity peaked.

 

Freddy,
Google "how does air and water get into the brake system" and you'll get lots of articles that answer your question.
Regards,
Tom

 

Remember that the brake hydraulic system can't be sealed. It has to vent and equalize pressure to the air because as the brakes wear the caliper pistons move and the system will need more fluid as this happens. Plus temperature changes will cause the brake fluid to expand and contract somewhat too. If it's not vented then it would build a vacuum in the hydraulics as the pistons move out with wear.

Most people don't see this because;
1. They don't look for it.
2. It's pretty small
3. You wear out the brake pads and replace them with new thicker ones.

That's why you need to retract the caliper pistons when doing a brake job. This forces brake fluid back up into the MC. Most will remove the MC cap when doing this but even if you don't the MC is vented to the atmosphere. So this is one way the brake fluid picks up moisture.
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Clubairth1, Thank you for the reply. I haven't had the need to pull the cap off the master cylinder so I'm speaking out of ignorance on my own car. However, are you telling me that the MC reservoir is actually vented to the open air and that there is not a cap seal with what looks like a small bellows that expands and contracts with pressure changes in the reservoir? That rubber bellows seal isolates the fluid from the air that does come through the vent hole. Maybe I'm too old, but that's how I remember master cylinders and a vented cap with a rubber seal under it. I wont argue against the knowledge that all rubber seals become microscopically porous over time and will allow air to creep through.

 

All brake systems have to be vented. This means contact with the atmosphere and moisture. This is easy to check with a brake fluid moisture checker if you don't believe it?
Here is a list of about 50+ brake fluid moisture checkers. Do you think there would be this many devices for sale if brake fluid was sealed from the atmosphere?
They are pretty cheap to so you can prove it for yourself without taking anybody's word for it.


Only about $15 too. I just assume the fluid is contaminated and I flush it.
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Freddy,

You can check if you want, in "modern years" brakes have never and will never change short of electric motor braking. This statement will probably be proven to be wrong now that I've said it.

I designed brake fill systems for one of the big 3 for the best selling vehicle platform in America - brake fluid chemical properties suck water until the next Tony Stark creates a stable fluid with the same compressible properties. The venting/implementation methods vary slightly, brake systems are not sealed to be intrinsically safe, but they are sealed to the best of our abilities until it becomes cost prohibitive. They are also servicable which gets in plenty of air moisture. In the factory, you even have a few moments where it can pick up some moisture before going to the customer (miniscule), but the older your vehicle is the more times this can happen.

Everyone and their mother should be checking and changing their brake fluid regardless of make/model every 3-5 years or whatever the manufacturer recommends. You might not need to do it when the Midas quick change recommends you do it, but it needs to be done to adhere to the "highest standard of safety".

Will you live if you skip it? Probably? But it costs me <$200 to have a shop do it, or a few hours if I do it myself.

 

You are correct. Yes, there are mastercylinders with such soft rubber sealing that follows the surface of the fluid. These are still used in motorcycles, ATV:s etc where the fluid resevour are in open air for the elements. However, nowdays when every penny are calculated by vehicle manufacturer, they are left out from most of the vehicles, since the cost of changing the fluid will set for the owner, not for the manufacturer. However: I would not like to test if the sealant have been working or not in a real life traffic.
Pushing flat out in a main straigh, leaving the brake point in last moment and when brake pedal went straight to the floor there was an skid marks, but not where they should not be. Lesson learned. (actually, needed 2 times )

 

Thanks, guys, I am now re-educated on the importance of getting my brake system flushed. I always knew about the significance of getting air/moisture into the system, but I did not realize how prevalent the problem is.
I come from old school habits and I thought the master cylinder and brake system was a practically closed system but I see that may not be the case. So, thanks. I'm overdue and will be changing that fluid ASAP.

 

That is good to know! It's strange that our repair system labor and price look up doesn't show brake fluid change for your car but I will definitely keep it in mind for our customers cars! Thanks for sharing!!