Yikes! No brakes!

[Donjames911]

My '97 D1 is my toy. I enjoy working on it as much as driving it. I have a GMC Sierra Z-71 4x4 as my DD. I took the Disco for it's weekly ride the other day just to run it. Coming out of the driveway, the brake pedal went to the floor, tho I could pump the system up.

Checking it out, I could find no leaks, but the reservoir was low. I filled it with DOT-4, and it did not help, and the brake fluid was again low. Air in the system is an obvious cause, but it wont fit in the garage (safari rack) and its cold here! The facts seem to rule out master cylinder piston blow-by.

Anyone have any other potential cause(s) for this problem?

 

[joey]

check for leaking brake lines... I had to replace my rear lines a few years back on my 97 D1.

 

[Donjames911]

Yikes

Thanks for the prompt response, Joey. I found a leak, it appears to be coming from the joint between the master cylinder and the brake servo. There is fluid on the lower lip of the MC mounting flange and enough fluid on the inner fender well beneath to remove the paint, so I can't rule out the flange itself. Your thoughts?

Also, does the reservoir just pull off the master cylinder?

 

[joey]

If I recall correctly there are just two bolts that hold the Master Cylinder to the Servo.

 

[Donjames911]

Master cylinder

Yes Joey, two bolts. I was hoping for specifics regarding the possible cause(s) if the leak(s), Also, can you tell me if the reservoir just pops off the master cylinder?

And I'd just like to add your knowledge of the D1 has always been accurate and very helpful. Thanks.

 

[joey]

Cause, could just be a bad seal... 2 bolts and if I recall correctly it just pulls off.

 

[Donjames911]

Thanks Joey

 

[rellard]

I also had the same issue with my '97 - it would come and go and scare the beejesus out of me. No leaks, no other symptoms. The final fix? I replaced the right front caliper and the issue quit - this was about 2 years ago. I suspect it was the source of some air entrainment, but nothing confirmed.

 

[Donjames911]

@rellard, TY for the input. If no obvious leakage, what led you to the RF caliper?

 

[joey]

The other issues with brakes on the D1 at least is the ABS sadly has issues... 8 years ago I removed the ABS 30 amp fuse and have never since had a brake related issue (other than brake line leakage.)