m170 Bleeding Brakes

bl5211a · Post by **bl5211a** » Thu May 29, 2014 6:57 pm

hello, I put all new brake lines, and rebuilt master cylinder and wheel cylinders.

Put brake fluid in master cylinder, but cant pump fluid into lines? I opened farthest line to bleed, but i can just keep opening , pump , close, release , and open, etc
Any suggestions on how i can push the fluid to the wheel cylinders?

Brian

M606BR · Post by **M606BR** » Thu May 29, 2014 9:32 pm

Did you bench bleed the master cylinder? You need to do that, otherwise you won't get brake fluid into brake lines.
See the picture attached to Ryan's post in the link below:

http://www.willysmjeeps.com/v2/modules. ... pic&t=2850

bl5211a · Post by **bl5211a** » Thu May 29, 2014 9:58 pm

is there a pressure bleeder that fits the m38a1/ m170 master cylinder?

bl5211a · Post by **bl5211a** » Fri May 30, 2014 12:38 pm

I did not bench bleed, is there another way now that it is in jeep, or do i need to remove the master cylinder ?

M606BR · Post by **M606BR** » Fri May 30, 2014 9:43 pm

You can do without removing it. You will need to disconnect both brake lines from master cylinder and connect 2 small pieces of tube bent upward, both going into the opening of the master cylinder. Then start pumping. While you pump, you will see brake fluid going back to master cylinder. Keep pumping until you see no bubbles going back to master cylinder. Then you will disconnect those small pieces of tube and reconnect the brake lines. Afterwards you will need to bleed the wheel cylinders again.

Hope it helps.

bl5211a · Post by **bl5211a** » Sat May 31, 2014 10:06 am

Thanks for the help.

Here is what i did and it worked well.

I removed the small pipe-plug from the Master cylinder lid. I set my compressor to 8 PSI

I cracked the farthest wheel end

Pressurized the master cylinder and waited until system pushed fluid to end.

Checked level and filled.

Then did the remaining wheel ends. Brakes are solid as a rock. Also note, I used Dot 5 and had no sponginess, brakes system is hard and works extremely well.

Brian

M606BR · Post by **M606BR** » Sat May 31, 2014 4:48 pm

Brian,
It's good to hear that. You have found an easier way to do it.
I changed all brake lines and wheel cylinders in my M606 a couple of years ago. After the changing, the brakes are working very well and the system is finally reliable.
DOT 5 fluid is hard to find around here. So I use DOT 5.1 fluid which is a higher performance and less hygroscopic fluid than DOT 4.

Post by **wesk** » Sat May 31, 2014 5:05 pm

Air will be absorbed in a short period of use by the DOT 5 and the notorious sponginess will be forever present on your jeep. Make sure the heat shield is in place for the master cylinder or the sponginess will become much worse.

artificer · Post by **artificer** » Sun Jun 01, 2014 2:16 pm

I have never experienced aeration problems with DOT 5 & use it on every rebuild.
Vacuum bleeding helps rather than pumping the pedal.
Here is a good cheap simple brake bleeder.

Post by **wesk** » Sun Jun 01, 2014 11:28 pm

Well John good for you but this one we will have to agree to disagree on.

I won't argue it here. The data is plentiful and easily found by those looking for the best choice.