How to cap brake lines
 

I am thinking about removing my calipers to send them off for powder coating - just wondering if anyone has a good hack for capping the brake lines.

I realize that having the brake pedal depressed will stop fluid from leaking out, but being as how they might be out of the car for a few weeks, I figured it would be best to cap the lines.

We use some rubber/plastic caps we got from a parts store, but as we only use them for perhaps an hour or two, I don't know how well they will hold up for weeks. They do work well for our purposes, however.

Penny wise pound foolish....
Once you reinstall the calipers your going to have to bleed the entire system.
By the time you do that all the fluid you tried to save will most likely be purged from the system.
You should be able to fill and bleed a completely dry system with 1-1.5 bottles of fluid.

> You should be able to fill and bleed a completely dry system with 1-1.5 bottles of fluid.

I don't mind doing that - just wondering if there are adverse effects - I've never purposely filled my lines with air. Any issue with having to also bleed the ABS/PSM?

If you get air into the ABS/PSM control network and pump, you will need a Porsche diagnostic tool to run a special system activation protocol while bleeding the system to get that air out. This is why we cap the lines, even though we have the diagnostic tool to correct the issue, it just adds unnecessary time to a job, and $ to the customer's bill.

I don't see any issues....
When you remove the calipers your going to introduce air into the system no matter how fast you cap off the lines. No way to control where that air migrates to.
If you have a OBDII scanner with a Porsche Program it makes it a little easier as you can activate the ABS/PSM with the scanner.
But I have never had any issues bleeding any type of system on any car.

Perhaps if I am missing something JFP in PA will jump in and clue us both in.

Since the calipers are lower than the brake reservoir, removing the calipers does not introduce air into the system - that's why the fluid is leaking out. Yes, when you put the calipers back on, they will be full of air that will need to be purged, but in no part of the process should air be getting sucked back into the system.

Your car do it your way;)

When you open the lines at the caliper, and then cap them, the air is trapped at the capped fitting and stays there. When the line is subsequently reconnected and then the system flushed, the air retained at the cap point is forced out of the system at the caliper bleeders.

If the line is not capped, that portion of the line system will slowly gravity drain all the way back up to the ABS pump and control network, getting air into an area that is difficult to get it out of without the diagnostic tool to cycle the valves and pump circuits while flushing the system. The air doesn't move up the system when it is full of fluid, the fluid drains out, letting the air in.

We regularly see cars that "have no brakes" or are throwing ABS/PSM codes after removing the calipers for one reason or another, during which time the lines were not capped. We hook up our Motive bleeder system, connect the diagnostic tool to cycle the ABS system, and a few min. later, the car can stop on a dime.

As the fluid drains from the lines, it might not be pulling air into the reservoir at the top of the system, but air is flowing into the lines from the bottom as more fluid drains out. I don't really know how long it would take for a bubble to rise if the line were to be capped, but I'd be looking for rubber plugs from a hardware store. I imagine limiting the amount of fluid that leaks out would limit the migration of air.

Lowes and Home Depot don't sell little tapered plugs- around here we have McLendons that still carries stuff like that.

https://www.amazon.com/Assorted-Sizes-Solid-Rubber-Stoppers/dp/B07MZJG3FC/ref=asc_df_B07MZJG3FC/?tag=hyprod-20&linkCode=df0&hvadid=312135717511&hvpos=&hvnetw= g&hvrand=827552023521595362&hvpone=&hvptwo=&hvqmt= &hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9052871&hvta rgid=pla-652514712186&psc=1

If the link works, it's just meant to illustrate what I'm talking about, they look like they're the wrong size for this particular use.

With the exception of using something like a motive bleeder system I do what you do.
Doesn't take very long and if the rest of the system is up to par I don't have any issues.

I used the clear plastic tubing suggested by Pedro from pedrosgarage.com. Worked well for the couple weeks I had the calipers off the car. https://www.pedrosgarage.com/site-3/caliper-painting.html

Sent from my SM-S901W using Tapatalk

If you do it quickly, and the lines are not left open for very long, it is not an issue. But if they are left open for a prolonged period, they will drain, and there will be potential problems.

More like this:

https://m.media-amazon.com/images/I/...webp_QL65_.jpg

I reached out to a powder coater, and he recommended these:

https://www.amazon.com/Performance-Tool-W83147-line-stopper/dp/B08L8D15L5/ref=psdc_15706941_t2_B0169LYNLA?th=1

Big question - are the lines 3/8 or 5/16 ID?

I'm sure they would work but are a $12 fix for a 5-cent problem.....

Brake hard lines are 3/16 or 4.75MM.