 brake fluid leak, washer for brake switch at MC |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
| hndyhrr |
 Sep 17 2025, 09:43 AM
Post
#1
|
|
Senior Member  Group: Members Posts: 645 Joined: 1-September 13 From: central point,oregon Member No.: 16,332 Region Association: Pacific Northwest 
 |
Discovered a fluid leak at the brake switch in the Master Cylinder (19mm).
Two questions, What kind of washer is between switch and MC? Metal/fiber? If I take the switch out will I loose the brake fluid? Thanks Renee (IMG:style_emoticons/default/driving-girl.gif) (IMG:style_emoticons/default/headbang.gif) |
   |
 
|
  |
Replies
| Superhawk996 |
Sep 17 2025, 06:40 PM
Post
#2
|
|
914 Guru Group: Members Posts: 7,392 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch
|
Master cylinder failing doesn’t make a noise - the seals within just start leaking internally and bypassing pressure
If the fluid is on the switch - make sure it isn’t just leaking from the supply line grommets at the top of the m/c and dripping down onto the switch. There was also a bad batch of 914Rubber master cylinders that were prone to leaking at the Welch plug up top and that conceivably could leak down onto the switch too. The switch itself and its plunger / actuator is in a dry section of the master cylinder between the seals. You can remove the switch without losing brake fluid. However, if you find fluid inside, it’s a sure sign the seals on the pressure differential piston(s) have gone bad. Here’s what the internals are:  Arrows pointing to the differential pressure piston seals |
|
|
|
| hndyhrr |
Sep 17 2025, 07:43 PM
Post
#3
|
|
Senior Member Group: Members Posts: 645 Joined: 1-September 13 From: central point,oregon Member No.: 16,332 Region Association: Pacific Northwest
|
QUOTE(Superhawk996 @ Sep 17 2025, 05:40 PM)  Master cylinder failing doesn’t make a noise - the seals within just start leaking internally and bypassing pressure If the fluid is on the switch - make sure it isn’t just leaking from the supply line grommets at the top of the m/c and dripping down onto the switch. There was also a bad batch of 914Rubber master cylinders that were prone to leaking at the Welch plug up top and that conceivably could leak down onto the switch too. The switch itself and its plunger / actuator is in a dry section of the master cylinder between the seals. You can remove the switch without losing brake fluid. However, if you find fluid inside, it’s a sure sign the seals on the pressure differential piston(s) have gone bad. Here’s what the internals are: Arrows pointing to the differential pressure piston seals Thanks for reply I've attached pic, it's leaking where the blue line is. Felt the top of MC and it is dry as a bone.  |
|
|
|
Posts in this topic
hndyhrr brake fluid leak Sep 17 2025, 09:43 AM
Superhawk996 If you are getting fluid into the switch the m/c a... Sep 17 2025, 09:47 AM
hndyhrr
If you are getting fluid into the switch the m/c ... Sep 17 2025, 10:53 AM fiacra
There was also a bad batch of 914Rubber master c... Sep 17 2025, 11:34 PM dtmehall I would add, that if you're investigating this... Sep 17 2025, 08:15 PM bkrantz I suggest loosening the switch. If fluid drains o... Sep 17 2025, 08:23 PM hndyhrr Thanks for the help and suggestions. I will loosen... Sep 17 2025, 08:32 PM |
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 18th September 2025 - 02:35 AM |
Invision Power Board
v9.1.4 © 2025 IPS, Inc.