Brake fluid replacement with Motive System

[ChiefDork]

There is a lot of fluid in the brake plumbing related to the ABS system. I am assuming there are special steps that one must follow in order to flush the fluid out of that part of the braking system.

Am I the only one concerned about the fluid left in that part of the system? Or, does the normal bleeding procedure flush the ABS area too? Perhaps since the ABS parts are so far from the calipers, and thus the main source of heat, my concern is not warranted?

I am asking to gain knowledge, not cast aspersions on what others have already posted.

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[Tomster]

He doesn't draw it out first but I see what you're saying. Draw it out if the scenario is switching to racing fluid. Once enough is drawed out, refill the master cylinder reservoir back to the max fill line? Then pour another liter into the motive bleeder and push it through that way?

Not unless you are putting new pads in. Brake fluid levels go down as your pads wear. Make a note of the brake fluid level and when it is all said and done, the level should be right where you left it.

As for the bleed process, the motive bottle will continue to add fluid to your reservoir as it is bled out. All you should have to do is keep pumping the bottle to retain the required pressure.

 

[NoXiDe]

Not unless you are putting new pads in. Brake fluid levels go down as your pads wear. Make a note of the brake fluid level and when it is all said and done, the level should be right where you left it.

As for the bleed process, the motive bottle will continue to add fluid to your reservoir as it is bled out. All you should have to do is keep pumping the bottle to retain the required pressure.

Gotcha, I do think that now that I read a bit more about the motive bleeder that I'd have to agree going with the method of drawing it most of it out first, filling the mater reservoir with the new stuff, DO NOT FILL Motive Bleeder just pressurize it to 14 PSI, and begin to flush may be a better idea. Obviously, the motive bleeder will need to be depressurized in order to top the master reservoir again with more brake fluid if needed to continue any other calipers. Continue to maintain the psi. Fast forward, once done just top of the master reservoir if needed? Agreeing with BoomBoy to prevent having to clean the motive container. Which means being super careful not to run the system completely dry throughout this whole process. I believe this method is called Motive Bleeding (Dry Method) versus Motive Bleeding with Fluid in the container method.

Can someone share how much needs to be drawn out? Seems like a really small reservoir. Top yellow is max, bottom yellow is minimum.

Tom, I think in my case that I stored my OEM pads for a track event and swapped to PowerStop Z26 just recently in March 2020. It would be difficult to track when a flush is needed. To be fair, I'd have to do it based on mileage. My last brake flush was in January 2019 and exactly 8,640 miles by now through Ford when I had the R Calipers put on. I can't see monitoring anymore through pad wear. The Z26 pads probably have 2-3K miles by now with the same fluid. Along with my oil, cup mileage, I'll now also add brake fluid mileage to my excel doc. This is my current fluid since 8K miles. I had to open the cap since it was difficult to measure without doing so. Appears to be a tad below the max fill line.

 

[Tomster]

Gotcha, I do think that now that I read a bit more about the motive bleeder that I'd have to agree going with the method of drawing it most of it out first, filling the mater reservoir with the new stuff, DO NOT FILL Motive Bleeder just pressurize it to 14 PSI, and begin to flush may be a better idea. Obviously, the motive bleeder will need to be depressurized in order to top the master reservoir again with more brake fluid if needed to continue any other calipers. Continue to maintain the psi. Fast forward, once done just top of the master reservoir if needed? Agreeing with BoomBoy to prevent having to clean the motive container. Which means being super careful not to run the system completely dry throughout this whole process. I believe this method is called Motive Bleeding (Dry Method) versus Motive Bleeding with Fluid in the container method.

Tom, I think in my case that I stored my OEM pads for a track event and swapped to PowerStop Z26 just recently in March 2020. It would be difficult to track when a flush is needed. To be fair, I'd have to do it based on mileage. My last brake flush was in January 2019 and exactly 8,640 miles by now through Ford when I had the R Calipers put on. I can't see monitoring anymore through pad wear. The Z26 pads probably have 2-3K miles by now with the same fluid. Along with my oil, cup mileage, I'll now also add brake fluid mileage to my excel doc.

No, draw all the old fluid out of the reservoir (but still leave the standpipe covered) and then fill the reservoir and the bleeder bottle with the new fluid. This way you won't have to stop and fill the reservoir a bunch of times. The bleeder will transfer fluid to the reservoir as needed and as it is bled out of the system.

 

[NoXiDe]

No, draw all the old fluid out of the reservoir (but still leave the standpipe covered) and then fill the reservoir and the bleeder bottle with the new fluid. This way you won't have to stop and fill the reservoir a bunch of times. The bleeder will transfer fluid to the reservoir as needed and as it is bled out of the system.

@Tomster I've been somewhat convinced by the internet that it's a nightmare to clean the motive bleeder and that it's led the plastic to become deteriorated over time causing massive leaks. I do know AutoFanatic does suggest cutting the end of the plastic after each use to prevent the leaks so maybe that is the fix for that problem but still leaves the cleaning the motive bleeder as an obstacle.

I updated the post above as I know myself and others are a bit clueless. I'm not quite sure where the standpipe may be on that reservoir. I assume it's the below the bottom part of the plastic reservoir?

 

[JAJ]

Okay, so I've been doing this stuff since about 2005 and I've tried every method and tool under the sun for bleeding brakes. This is where I ended up after lots of trial and error.

I use a Sealy bleeder for "regular" bleeding work - it's like a Motive (I have one of those too) but it's better made and it has a specially designed reservoir cap that has a small tube that goes down into the reservoir. When you release pressure, the air pocket at the top of the reservoir pushes fluid out of the reservoir down to the end of the little tube. You get the right final fluid level without messing around. Thing is, I only use this for the grocery getters in the family - two BMW's and an SUV.

I pressurize the Sealy through a Schrader valve I installed on the fill cap. I hook it to a pressure regulator on my compressor. 20 PSI works just fine.

For the GT350 I have Stahlbus one-man bleeders on the calipers. They have a special type of ball valve in them that you can either open all the way to do a flush, or just a half-turn and you can do a pressure bleed. Pressure bleeding is different than flushing. When you pressurize the system with the brake pedal, any air bubbles are compressed and dislodged so they come out the bleeder. The gentle, even pressure from a Sealy or a Motive doesn't have this effect. That said, if your system has no air in it when you start, it won't have air in it when you finish with either method.

My newest secret weapon is a brake fluid moisture meter. Very handy gizmo.

Regardless of which vehicle I'm doing, I suck fluid out of the reservoir first for exactly the reasons that @Tomster mentioned. If I'm using the Sealy, I leave the level low and just hook up. The pressure bleeder takes care of refilling the reservoir. On the GT350 I top it up manually and start pumping the brake pedal.

On the caliper end, I pump fluid into a catch bottle, but after I've taken out a reasonable amount of fluid, I run some into a glass jar and check it with the moisture meter. When the reading drops to the same moisture level as fresh fluid, I'm done on that corner and I move on to the next one. No guesswork.

By the way, cleaning a Motive or anything else in the kit is super easy. Turns out that warm water and a bit of dish detergent works just fine. The ether alcohols in brake fluid are miscible with water, so when I'm done with a bleed cycle, I just wash all the gear in the kitchen sink and put it in the boiler room to dry. A couple of weeks at 80 degrees and it's ready to go for the next job. Same applies to brake fluid spills - wipe up what you can and rinse the area with water. Job done.

 

[JAJ]

@Tomster I've been somewhat convinced by the internet that it's a nightmare to clean the motive bleeder and that it's led the plastic to become deteriorated over time causing massive leaks. I do know AutoFanatic does suggest cutting the end of the plastic after each use to prevent the leaks so maybe that is the fix for that problem but still leaves the cleaning the motive bleeder as an obstacle...

As I said in the earlier post, cleaning is easy. As for the plastic tubing, it does deteriorate unless you keep it clean.

One of the reasons I like the Sealy bleeder is that it has silicone hoses that don't deteriorate even if you leave the fluid in them.

 

[ZPD]

For my own edification- what is the advantage of using a pressure system instead of a vacuum? I always hooked up a vacuum (not a shop vac mind you- a HF vacuum) pulling a vacuum on a glass jar with a hose connected from the jar to the caliper bleed screw. I just kept the resevoir topped off while the jar was filling.

 

[Tomster]

@Tomster I've been somewhat convinced by the internet that it's a nightmare to clean the motive bleeder and that it's led the plastic to become deteriorated over time causing massive leaks. I do know AutoFanatic does suggest cutting the end of the plastic after each use to prevent the leaks so maybe that is the fix for that problem but still leaves the cleaning the motive bleeder as an obstacle.

I updated the post above as I know myself and others are a bit clueless. I'm not quite sure where the standpipe may be on that reservoir. I assume it's the below the bottom part of the plastic reservoir?

You are way overthinking this

 

[matthewr87]

My newest secret weapon is a brake fluid moisture meter. Very handy gizmo.

I just tested my fluid with a brake fluid moisture meter and it shows <1% water. Is it worth changing? Car has 4500 miles and I've gone to a couple of track events. I am not very hard on the brakes however since my stock pads are still at 8 mm.

 

[JAJ]

I just tested my fluid with a brake fluid moisture meter and it shows <1% water. Is it worth changing? Car has 4500 miles and I've gone to a couple of track events. I am not very hard on the brakes however since my stock pads are still at 8 mm.

How long since the fluid was new? Mileage doesn't matter as much as time-since-new. If it's over about six months, then I'd suggest that you do a bleed before your next track event. It may not be necessary, but it'll give you a known-good baseline that you can count on and that you can measure from.

When you do it, measure the moisture at the calipers right at the start of the bleed. That's where the heat is so that's what matters. Compare that moisture level with new fluid (your meter may not read new fluid as zero so check it first). If what comes out of the caliper is the same as new, then you probably didn't need to bleed, but if it's up a percent or so, then it was definitely time.

 

[Tomster]

If anyone cares....

Today I flushed my GT500 CFTP brake system fluid and replaced with castrol SRF.

It went exactly like this...... use a turkey baster with a small hose attached to the end to nearly empty reservoir. Fill reservoir with Castrol SRF. Dump remaining liter into motive power bleeder. Connect to reservoir. Pump up to 15 PSI and incrementally bleed fluid from most distant caliper working my way back to nearest. Watch for fluid color change from (whatever you have) to clear. Use a toothpick in each bleeder valve to empty excess. Wipe. Replace bleeder valve cover. Move onto next one until done.

Relieve pressure from motive bottle. Empty excess fluid back into SRF bottle. Drain bottle and lines. Done. Big deal.

 

[NoXiDe]

If anyone cares....

Today I flushed my GT500 CFTP brake system fluid and replaced with castrol SRF.

It went exactly like this...... use a turkey baster with a small hose attached to the end to nearly empty reservoir. Fill reservoir with Castrol SRF. Dump remaining liter into motive power bleeder. Connect to reservoir. Pump up to 15 PSI and incrementally bleed fluid from most distant caliper working my way back to nearest. Watch for fluid color change from (whatever you have) to clear. Use a toothpick in each bleeder valve to empty excess. Wipe. Replace bleeder valve cover. Move onto next one until done.

Relieve pressure from motive bottle. Empty excess fluid back into SRF bottle. Drain bottle and lines. Done. Big deal.

Awesome write up, out of curiosity. While on the caliper, do you bleed yours from inside to outside or outside to inside. I could see someone else asking. Your write up is near perfect.

 

[Tomster]

Awesome write up, out of curiosity. While on the caliper, do you bleed yours from inside to outside or outside to inside. I could see someone else asking. Your write up is near perfect.

There are so many opinions in this matter. I bleed from the outside to the inside and then the outside once again.

To verify when the fluid changes to new, I use a white piece of paper as a background to look at the stream as it comes out of the caliper. My new OEM fluid was yellow. Castrol SRF is clear. A white piece of paper as a background helps determine when you have new fluid.

If you have old fluid, the color of the old fluid will be much darker (you probably won't need a background to determine when you have new fluid).

If anyome is going to track, and drive it like you stole it (heavy braking), you ought to seriously consider a high boil temp fluid like SRF or Motul.

 

[matthewr87]

One more question. What volume of fluid do you need for the flush? I bought 2 pints of the OEM stuff. Will that be enough?

Also, do you guys use a torque wrench to close the bleeders? If so what is the recommended torque?

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