1986 XJ-SC brake flush

After 4 year hiatus from weekend driving, I am back! The first thing that I noticed - brakes are spongy and barely stop the car. Looks like complete brake bleeding/flush needed. Does anyone have good pictures of the location of bleeding valves for front and rear? the gasket around brake fluid reservoir are shot - is there any way to replace it or I need to find a gasket that would fit there?
Any particular sequence (eg start from the furthest valve to the closest)? How much fluid does the whole system hold (in case of flush)? What do you do with used/old brake fluid? There will be more to come!

I just did mine a couple months ago on 88 XJS, car had been sitting for 7 years. I used three bottles (32 oz each) of Prestone Dot4 synthetic to give it a really good flush. Overkill, but i wanted ALL fluid out of there. Only $9 a bottle, so nothing crazy.

I like using the Motive power flush on all my cars. I had to buy a generic adapter for the XJS brake fluid reservoir, and my own clamps to hold it tight.

All cars, you always start with the caliper farthest away from the reservoir. For U.S. LHD, that’s RightRear, then LeftRear, then RightFront then LeftFront.

The rear inboard brakes are a pain, but it’s doable. Stubby open end wrenches made it easy. Can’t remember the size.

Front brakes are piece of cake. Different size from rear. If the rubber caps on the bleeding valves look shot, may as well replace them, cheap and easy to find.

I’ve never really understood that. The fronts and the rears are only connected at the master cylinder. I don’t see how it makes a whit of difference which one you start with or what order you do them in.

Yep. If the rears are inboard, they are SAE, while the fronts are metric.

Is there enough space for deep socket and a wrench? Is metric 11mm? What is the SAE?

IIRC, the SAE fittings at the rear are tiny. Easy to round off! Always best to break them loose with a deep 6-pint socket.

So 11mm front and back is what size?

top of my head, I think the rears were 7/16"??? I was unable to get a socket in there, if I remember they sit just under the underbody. I ended up using a combination wrench with 12 points, no stripping. I did give them a good brake cleaner spray first, and then some PB blaster just in case.

I will look for that 12 point 7/16 before starting the job.
aside from the brake job (well the most important really, for obvious reasons) - I have multiple smaller questions - just for the clarity of the forum, should I make one bigger thread and post questions there, or rather go one-by-one ?
Thanks guys!

how much brake fluid I should buy and which dot spec would You recommend?
What do You guys do with old brake fluid?

You should create separate threads with specific topics in the subject line and model year and engine if applicable in the text. If you combine too many things into one post it will be confusing for everyone involved and it will discourage replies from those who can help with one thing but not the others. If you don’t include your model year and engine ( if applicable to the subject) no one will have a clue what car you have and either not reply or possibly reply with info that doesn’t pertain to your car. This happens regularly unfortunately.


It might be cheaper to use Methylated spirits (denatured alcohol) to do the flush, this will remove any water from the system as it is missable with water. I’m surprised you can still but DoT 3 I use DoT 5.1 in my cars.

Dot 5.1 is better, but Dot 4 synthetic is not that far behind. It’s miles better than the original Dot ? non-synthetic used on these cards. If I raced my XJS, then I’d probably upgrade to 5.1

Also, it’s more trouble to upgrade, as the two can’t be mixed.

Greg that’s where the flush with Meths comes in.

yeah, that makes sense.

Too much work for me to provide a bit of a higher boiling point that I’ll never reach. :wink:

Also, memory fail, I used Dot 4 synthetic, not Dot 3. I’ve corrected my above posts.

Just to close the topic - do I need more than 32oz of brake fluid just replace current one, without some extra diligent flush ?

Can’t help there, I deal in litres :slight_smile:

Depends how you flush. I always use about 1 1/2 bottles when using my pressure bleeder. You don’t want to run out in the container.

Doing a crazy flush on my XJS, I ended up using 2 1/2 bottles.

Is a brake flush going to eject all the fluid and crap from the caliper pistons?

Fluid, yes, crap? Not necessarily, the bleed nipple is only a small orifice. Having said that there shouldn’t really be any rubbish in there unless the system has been very badly maintained.