Master Cylinder accidentally ran DRY. Help!
Thread Starter
Newbie
Joined: Aug 2020
Posts: 2
Likes: 2
From: KS
GL450
Master Cylinder accidentally ran DRY. Help!
When I was installing a new caliper, rotor, and pad (front left), I accidentally let the master cylinder run dry overnight.
So, I think I have empty brake fluid from the master cylinder to the LF (no fluid at bleeder screw).
What would be the correct procedure I need to do?
The MC bench bleeding (outside of the car) seems to be beyond my newbie DIY skill.
However, I have MC bleeder kits (https://www.dormanproducts.com/p-1646-13999.aspx) and a Motive Product Pressure Bleeder.
After some googling this week, my current plan to do is
(1) MC bleeding on the car using the bleeder kit,
(2) Gravity bleeding FL.
(3) Pressure bleeding RR, RL, FR, FL
Am I right or is (2)-(1)-(3) better? Anything I missed?
Also, I am not sure whether the ABS system bleeding at Dealer is needed after this.
Please help!
Thanks,
LL
So, I think I have empty brake fluid from the master cylinder to the LF (no fluid at bleeder screw).
What would be the correct procedure I need to do?
The MC bench bleeding (outside of the car) seems to be beyond my newbie DIY skill.
However, I have MC bleeder kits (https://www.dormanproducts.com/p-1646-13999.aspx) and a Motive Product Pressure Bleeder.
After some googling this week, my current plan to do is
(1) MC bleeding on the car using the bleeder kit,
(2) Gravity bleeding FL.
(3) Pressure bleeding RR, RL, FR, FL
Am I right or is (2)-(1)-(3) better? Anything I missed?
Also, I am not sure whether the ABS system bleeding at Dealer is needed after this.
Please help!
Thanks,
LL
Last edited by overlandpark; Aug 18, 2020 at 04:15 PM.
MBWorld Fanatic!
Joined: Aug 2005
Posts: 1,306
Likes: 204
From: Sarasota, Florida
2023 E450 Cabriolet, 2019 F150 Platinum, 2014 Dodge Challenger R/T
Not done this on anything this new but one issue you may run into is that master cylinder rod may not bottom out with the brake pedal and you will never get all the air out... hence bench bleeding you can bottom out the rod....
Others will probably have more advice for you, there are a few mb techs here...
Others will probably have more advice for you, there are a few mb techs here...
Out Of Control!!
Joined: Sep 2018
Posts: 14,692
Likes: 4,584
From: unbegrenzt
2017 GLE350 4MATIC
When I was installing a new caliper, rotor, and pad (front left), I accidentally let the master cylinder run dry overnight.
So, I think I have empty brake fluid from the master cylinder to the LF (no fluid at bleeder screw).
What would be the correct procedure I need to do?
The MC bench bleeding (outside of the car) seems to be beyond my newbie DIY skill.
However, I have MC bleeder kits (https://www.dormanproducts.com/p-1646-13999.aspx) and a Motive Product Pressure Bleeder.
After some googling this week, my current plan to do is
(1) MC bleeding on the car using the bleeder kit,
(2) Gravity bleeding FL.
(3) Pressure bleeding RR, RL, FR, FL
Am I right or is (2)-(1)-(3) better? Anything I missed?
Also, I am not sure whether the ABS system bleeding at Dealer is needed after this.
Please help!
Thanks,
LL
So, I think I have empty brake fluid from the master cylinder to the LF (no fluid at bleeder screw).
What would be the correct procedure I need to do?
The MC bench bleeding (outside of the car) seems to be beyond my newbie DIY skill.
However, I have MC bleeder kits (https://www.dormanproducts.com/p-1646-13999.aspx) and a Motive Product Pressure Bleeder.
After some googling this week, my current plan to do is
(1) MC bleeding on the car using the bleeder kit,
(2) Gravity bleeding FL.
(3) Pressure bleeding RR, RL, FR, FL
Am I right or is (2)-(1)-(3) better? Anything I missed?
Also, I am not sure whether the ABS system bleeding at Dealer is needed after this.
Please help!
Thanks,
LL
Gravity bleed cannot be relied upon. Bleed order:
1. right rear (passenger side North America)
2. left rear (driver side North America)
3. right front
4. left front
Thread Starter
Newbie
Joined: Aug 2020
Posts: 2
Likes: 2
From: KS
GL450
Thanks, mrmotoguzzi00 and chassis.
I did it yesterday. After (1) bench bleeding MC on the car and (2) pressure-bleeding all 4 wheels, my brake finally came back. I prepared 2L, but 1L fluid can was enough.
It is slightly soft, but it seems to run okay. No abs issues at all.
I did it yesterday. After (1) bench bleeding MC on the car and (2) pressure-bleeding all 4 wheels, my brake finally came back. I prepared 2L, but 1L fluid can was enough.
It is slightly soft, but it seems to run okay. No abs issues at all.
Last edited by overlandpark; Aug 28, 2020 at 09:04 AM.
MBWorld Fanatic!
Joined: Aug 2005
Posts: 1,306
Likes: 204
From: Sarasota, Florida
2023 E450 Cabriolet, 2019 F150 Platinum, 2014 Dodge Challenger R/T
Great News 
hopefully any remaining air bubbles will eventually find there way up to the master cylinder and dissipate
Mike
hopefully any remaining air bubbles will eventually find there way up to the master cylinder and dissipate Mike
Member
Joined: May 2017
Posts: 148
Likes: 18
mercedes w123 260e
Gravity bleed the system .Juist open up a bleed screw and let it drip drip till the fluid in the tank is low then refill ,next step is lock the nipple up move to the next caliper closest to the fluid fill tank .Do this till all cylinders have been done .
