Brake Fluid Flush B4 or after Pad Change?

[Noku]

Will be doing brake pad change on all four wheels and need to flush out my old brake fluid. Thinking that I should do the flush before changing the pads so that I have new fluid in the lines. Then when I compress the brake caliper piston I can bleed the old fluid out thru the bleeder screw. Would this give me a more complete fluid flush or am I missing something?

[beegeezy]

I think that would be overkill. Do the flush however it is easier for you.

[LynchburgCSI]

After.

[Hajoca]

During.

I like to open the caliper bleed screw and push the piston back, at this time, I have the bleed screw pointed down to drain/flush out any particles (usually some black pieces of corrosion or hose. seal material).

THen I do the line flush and bleed after the pad and rotors are re installed.

[Noku]

Originally Posted by Hajoca

During.

THen I do the line flush and bleed after the pad and rotors are re installed.

So do you mean that the line flush would be done before you pump the piston back up to engage the pads w/ the rotor?

What I'm trying to do here is to get fresh brake fluid into the caliper as opposed to the fluid that has been sitting in the lines because only heaven knows when the next time I'll flush the system again. Possibly the next time I do a brake job, which may be a while since the car is driven less than 10,000 miles/year. I know its recommended to flush every two years but maybe I can stretch it w/ new fluid in the caliper.

As it is now the fluid in the reservoir looks pretty nasty so I'm assuming that the fluid in the line must be as bad or worse since there isn't much or no circulation in the system. So most of the debris would accumulate in the caliper and lines. Or is this being presumptuous on my part and the fluid in the line isn't so bad as to effect the quality of the system and to be okay if it is placed in the caliper until a future pad replacement? BTW got the car used last month w/ 1037XX miles and doubt if the system has been flushed before since the previous owner changed pads just once on the front wheels. The back is original from the factory.

I would deeply appreciate any further comments.

[71Corolla]

When you compress the calipers, put a drain hose (I use vacuum hoses they work perfectly) on the bleeder and put that in a clean jar of fluid. Opening the bleeder valve when you compress the caliper will push the crud out instead of pushing up into the system if the bleeder value is closed. Close the valve, install your pads, then bleed the system.

Some people like to use a one way valve on the bleeder hose, I have one I purchased but I don't like it, so I rigged up one using a PCV valve. It's crude and has a bunch of different sized hoses stuffed together to make it all work, but it works awesome.

[Noku]

Originally Posted by 71Corolla

When you compress the calipers, put a drain hose (I use vacuum hoses they work perfectly) on the bleeder and put that in a clean jar of fluid. Opening the bleeder valve when you compress the caliper will push the crud out instead of pushing up into the system if the bleeder value is closed. Close the valve, install your pads, then bleed the system.

Some people like to use a one way valve on the bleeder hose, I have one I purchased but I don't like it, so I rigged up one using a PCV valve. It's crude and has a bunch of different sized hoses stuffed together to make it all work, but it works awesome.

I can just imagine what that must look like. But don't knock it till you try it, right?

[JohnGD]

I'd do it before.

Get new fluid into the system. Then open the bleeder screw as you push back the piston given the state of your brake fluid. Then bleed to make sure there is no air in the system. At this time the piston is back in and you can do all the pad work. I'd get a caliper tool kit from Harbor Freight, on sale for $9.87!! (if you don't use a large C-clamp) Dang I paid double years ago.

http://www.harborfreight.com/caliper...kes-40732.html

I'd use Castrol GT LMA (Low Moisture Activity) or Valvoline Synthetic brake fluid (also LMA).

MityVac in a bleeder setup (with bleeder cup) in Autozone's free loaner program works well. But you need to coat the bleeder threads with silicone brake gel to prevent air from getting sucked past the threads.

http://www.permatex.com/products/Aut...per_Lube_1.htm

That said, given the age of your calipers and the state of the brake fluid, I would actually rebuild the calipers by changing out all the rubber parts.

Originally Posted by Noku

So do you mean that the line flush would be done before you pump the piston back up to engage the pads w/ the rotor?

What I'm trying to do here is to get fresh brake fluid into the caliper as opposed to the fluid that has been sitting in the lines because only heaven knows when the next time I'll flush the system again. Possibly the next time I do a brake job, which may be a while since the car is driven less than 10,000 miles/year. I know its recommended to flush every two years but maybe I can stretch it w/ new fluid in the caliper.

As it is now the fluid in the reservoir looks pretty nasty so I'm assuming that the fluid in the line must be as bad or worse since there isn't much or no circulation in the system. So most of the debris would accumulate in the caliper and lines. Or is this being presumptuous on my part and the fluid in the line isn't so bad as to effect the quality of the system and to be okay if it is placed in the caliper until a future pad replacement? BTW got the car used last month w/ 1037XX miles and doubt if the system has been flushed before since the previous owner changed pads just once on the front wheels. The back is original from the factory.

I would deeply appreciate any further comments.

[71Corolla]

Originally Posted by JohnGD

That said, given the age of your calipers and the state of the brake fluid, I would actually rebuild the calipers by changing out all the rubber parts.

Very good idea, or just get rebuilds at your favorite parts store. The last time I did this they were surprisingly inexpensive. They had the rebuild kits but by the time I cleaned up the old ones etc. it was not worth my time and hassle. Plus the replacements were 100% clean and looked like new, so I painted them while I was at it.

[Noku]

Originally Posted by JohnGD

I'd do it before.

Get new fluid into the system. Then open the bleeder screw as you push back the piston given the state of your brake fluid. Then bleed to make sure there is no air in the system. At this time the piston is back in and you can do all the pad work. I'd get a caliper tool kit from Harbor Freight, on sale for $9.87!! (if you don't use a large C-clamp) Dang I paid double years ago.

http://www.harborfreight.com/caliper...kes-40732.html

I'd use Castrol GT LMA (Low Moisture Activity) or Valvoline Synthetic brake fluid (also LMA).

MityVac in a bleeder setup (with bleeder cup) in Autozone's free loaner program works well. But you need to coat the bleeder threads with silicone brake gel to prevent air from getting sucked past the threads.

http://www.permatex.com/products/Aut...per_Lube_1.htm

That said, given the age of your calipers and the state of the brake fluid, I would actually rebuild the calipers by changing out all the rubber parts.

Thanks for your thorough insights and links. Boy that caliper tool kit is a banging good deal, too bad its on backorder. Just got a spare torque wrench from HF which was only $9.99. Wish there was a forum on TN where folks can post good deals like that. Ebay has what looks to be the same caliper tool set but more money.

No AZ here in Hawaii but I'll check the other parts store for a loaner on the MV. If I can't get one guess my 225lb (mostly muscle) 17 yr old gonna have to help pops bleed them brakes. Hope he doesn't get

I Haven't seen any signs that the calipers are leaking but will have a better look once I remove the pads and check the seal on the piston.

[Noku]

Originally Posted by 71Corolla

Very good idea, or just get rebuilds at your favorite parts store. The last time I did this they were surprisingly inexpensive. They had the rebuild kits but by the time I cleaned up the old ones etc. it was not worth my time and hassle. Plus the replacements were 100% clean and looked like new, so I painted them while I was at it.

Will definitely look into that if I need too. Know a gal who retired from an automotive parts warehouse (wholesale) who may be able to hook me up w/ some.

[JohnGD]

Yeah, that torque wrench was a great deal. I also own Danaher-made Craftsman, but still picked one up at $9.99 (couldn't resist the deal). I compared it with the right-hand-torque only old HF one at 20 and 50 lb/ft. They clicked at the same time. Great value I have to say.

If you have to get a MityVac at HF I think they have them too. I pick the following up on sale IIRC $19.99 last Christmas, because my MityVac's seal seems to be going:
http://www.harborfreight.com/brake-b...kit-92474.html

In normal situations the seals harden. So when you release the brakes the square cut seal doesn't pull the piston back just that tiny bit. Brake drags, rotor warms up, etc. That's why I periodically rebuild them, including some nasty parking-brake-in-caliper ones (that's why the HF caliper kit comes in handy). Like 71Corolla said, rebuilt calipers are cheap and with many new components in there anyway. But I enjoy doing rebuilds, including halfshafts with Redline CV-2 synthetic grease. So YMMV.

Originally Posted by Noku

Thanks for your thorough insights and links. Boy that caliper tool kit is a banging good deal, too bad its on backorder. Just got a spare torque wrench from HF which was only $9.99. Wish there was a forum on TN where folks can post good deals like that. Ebay has what looks to be the same caliper tool set but more money.

No AZ here in Hawaii but I'll check the other parts store for a loaner on the MV. If I can't get one guess my 225lb (mostly muscle) 17 yr old gonna have to help pops bleed them brakes. Hope he doesn't get

I Haven't seen any signs that the calipers are leaking but will have a better look once I remove the pads and check the seal on the piston.

[Noku]

^ Hey John, would this do instead of what you recommended earlier to seal the bleeder while flushing?

Amazon

Amazon

Got some handy.

Also I ran across this on the HF site http://www.harborfreight.com/brake-f...der-92924.html
Would this be a better option since I have an air compressor? My only concern is if the adapter on the refill bottle would properly seal it to the brake fluid reservoir and not leak fluid out. Hoping that you've had experience w/ this kit or something similar.

Thanks for your info about the piston seals hardening over time. Wanna do the job right the first time.

[JohnGD]

The ceramic lube is great for anchor pins and caliper/pad contact points. It has ceramic particles in there, similar to how moly lube works in CV joints. However, that's the same reason I personally wouldn't use it. It can introduce particles into the system. I'd use the pure Permatex synthetic gel, which I also use as an assembly lube if I don't use just brake fluid. A packet is about $1.10 at many parts store counters.

The HF tool is similar to the MityVac except you're using a constant vacuum source. No sore muscles. As far as the feed bottle goes, you don't need an air tight seal, the bottle shouldn't leak out. In fact, many just invert the 12oz brake fluid bottle. Just don't let dirt get into the system. Vacuum out the existing old fluid from the reservoir first.

If you can still push back the pistons easily, then there may be no need to change out the seals. But if you do need to remove the calipers it helps to depress the brake pedal by using a brick or a pedal depressor. This way the master cylinder doesn't bleed dry and you have to bench bleed the thing. Or tickle the ABS module to get the air out (yes, even on Bosch 5.3 systems).

Originally Posted by Noku

^ Hey John, would this do instead of what you recommended earlier to seal the bleeder while flushing?
http://www.amazon.com/gp/product/B0018PSASU/ref=oss_product Got some handy.

Also I ran across this on the HF site http://www.harborfreight.com/brake-f...der-92924.html
Would this be a better option since I have an air compressor? My only concern is if the adapter on the refill bottle would properly seal it to the brake fluid reservoir and not leak fluid out. Hoping that you've had experience w/ this kit or something similar.

Thanks for your info about the piston seals hardening over time. Wanna do the job right the first time.

[Noku]

Originally Posted by JohnGD

The ceramic lube is great for anchor pins and caliper/pad contact points. It has ceramic particles in there, similar to how moly lube works in CV joints. However, that's the same reason I personally wouldn't use it. It can introduce particles into the system. I'd use the pure Permatex synthetic gel, which I also use as an assembly lube if I don't use just brake fluid. A packet is about $1.10 at many parts store counters.

The HF tool is similar to the MityVac except you're using a constant vacuum source. No sore muscles. As far as the feed bottle goes, you don't need an air tight seal, the bottle shouldn't leak out. In fact, many just invert the 12oz brake fluid bottle. Just don't let dirt get into the system. Vacuum out the existing old fluid from the reservoir first.

If you can still push back the pistons easily, then there may be no need to change out the seals. But if you do need to remove the calipers it helps to depress the brake pedal by using a brick or a pedal depressor. This way the master cylinder doesn't bleed dry and you have to bench bleed the thing. Or tickle the ABS module to get the air out (yes, even on Bosch 5.3 systems).

Makes good sense about the lube, will go with what you suggested. Learned a lot from your posts, here and elsewhere. Very much appreciated.