Hydraulic fluid replacement - flush or bleed?

The fluid in my '06 is overdue to be changed. Through the window it is beginning to look like ice tea, on its way to becomming darker.

Then manual calls for totally draining the old fluid from the resevoirs and lines then replace with new and bleed all lines. The preferred method on this forum seems to be bleeding existing fluid through the bleeder valves while adding new fluid to the resevoirs. Please provide some insight or educated opinions of one procedure vs. the other.

Thank you.

 

There are a couple real good compressed air powered bleeders available through auto parts stores if you have a compressor. Either a Vac-U-La or a Mi-T-Vac, suck the fluid through the bleeders while keeping a fresh supply in the reservoirs, this will give the cleanest end result and is a hands-free operation other than keeping the reservoirs topped. Good luck!

 

Bleeding the clutch fluid is easily done manually by opening the reserve, cleaning it out, being careful not to spill any on the bike, putting in new, and then bleeding out the old at the slave cylinder, while refilling the reservoir. The front and rear brakes can be done that way, but are a little more difficult. The linked brake system makes it tricky, as there is a shared line between the two. The ABS solenoids are really tricky. The shop manual devotes several pages to it. If I didn't have ABS, and knew how to bleed brakes manuallly, I'd go ahead. but the vacuum systems are a sure thing if you want to spring for one.

 

Personally I would empty the reservoir, clean out the inside, refill with fresh fluid, and then pump that through the lines. That way you save yourself the possible headache of trying to get all those air bubbles out. JMO

 

By emptying the resevoir first, then adding new fluid before draining the lines, won't I run the risk of introducing air into the lines?

Thank you,

Gunzer

 

No, that's one of the advantages of doing it this way. Since you haven't emptied any fluid out of the lines, the level of fluid is right at the master cylinder and when you add fluid you keep air out of the lines.

 

I just ordered a hand operated Mityvac. I will attempt to DIY this fluid change when it arrives. I thank everyone that has weighed in on this thread.

Gunzer

 

I just did both my brake and clutch fluid a few months ago. I completely drained each system and refilled with new fluid. Unless you have sediment in the master cylinder or are really into bleeding your brake system, I would just keep adding fluid to the reservoir until the new fluid comes out the bleeders. The clutch isn’t bad; it’s pretty much a straight shot from the master cylinder down to the bleeder. The linked brake system is a different story. It took me a whole large bottle of brake fluid to finally get all the air out of the system. I used the mighty vac and wasn’t impressed. It did not seem to be able to be able to pull fluid through the system. I ended up doing it the old fashion way, squeezing the lever and closing the bleeder. I would recommend you read the manual before you start. There is a definite pattern to which bleeders you start with on the brakes.

Action

 

If you use the Mity-Vac make sure you have some teflon tape or other thread sealant for the bleed screws. If you don't seal them you will pull air past the threads and not fluid down the lines. And be very careful with the teflon tape, you don't pieces of it moving through your brake system.

When I install my Galfer SS lines I'm going to try to pump the fluid through instead of pulling it. I've used the Mity-Vac several times and sometimes it works great and sometimes it's a PIA.

 

When I completely back out the bleeder screws to apply telfon tape to the threads, will this cause fluid to leak or air to enter the lines?

 

Keep the info coming guys... I'm probably going to tackle this sometime this summer as well. Only worried about the brake side (go figure). Trying to decide whether a tool like the mity-vac or a six pack of beer with a buddy helping out is the better investment. After hearing that the mity-vac is hit or miss with being a PITA... a six pack and a helper seems that it might end up slightly ahead on the cuss scale lol.

 

If you pull the bleeder screws to apply the tape, make sure you don't have the top off the master cylinder, that way any leakage will be very minimal.

And always remember "BRAKE FLUID IS DEATH ON PLASTIC AND PAINT!!!"