Leaky master cylinder brake proportioning sensor
Melting Slicks
Joined: Apr 2003
Posts: 3,110
Likes: 6
From: Red Sox Nation! RI
You have a bad or stuck proportioning valve. Now that you say it's leaking elsewhere, I'd say you got a bad master. Take it back and get another one and you should be all set.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
so, with all this being said... if I leave the sensor out while bench bleeding this thing, shouldn't it not leak out of the hole that the sensor is at?
One thing that I find really wierd is that the spring that keeps the brake proportiioning assembly centered in the tube is so weak. Why even have it if it barely puts a pound of force on the assembly. I'm talking about that teenie spring that goes between the cap for the tube of the proportioning assembly and the assembly itself.
One thing that I find really wierd is that the spring that keeps the brake proportiioning assembly centered in the tube is so weak. Why even have it if it barely puts a pound of force on the assembly. I'm talking about that teenie spring that goes between the cap for the tube of the proportioning assembly and the assembly itself.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
update... I pulled the master off the car. I could see the oring like you guys mentioned. I took a look at the assembly that slides into the master. It didn't seem to be pushed in all the way. So, I pushed it in and I tried to bench bleed the master once again. I completely left out the proportioning sensor so that I could tell if it leaked.
After a couple pumps of the master to bleed it, it looked dry. However, it appeared to be leaking out of the copper colored breather. Every 3-4 pumps of the master a drop would come out of the copper thing on the bottom of the master.
Any suggestions on this? Shouldn't this part be dry too?
After a couple pumps of the master to bleed it, it looked dry. However, it appeared to be leaking out of the copper colored breather. Every 3-4 pumps of the master a drop would come out of the copper thing on the bottom of the master.
Any suggestions on this? Shouldn't this part be dry too?
Melting Slicks
Joined: Apr 2003
Posts: 3,110
Likes: 6
From: Red Sox Nation! RI
- No, it shouldn't leak with the sensor removed.
- I have no idea why that end cap spring is weak. My guess is the prop valve doesn't rely on it for the tension, as they're usually stuck in the bore anyway.
- The proportioning valve not being pushed in all the way would be a valid explanation for leaking around the sensor.
- Copper colored breather - Ya got me there. Without looking at my car, I'm not sure what you mean. Though there shouldn't be any brake fluid on the outside of the master.
- I have no idea why that end cap spring is weak. My guess is the prop valve doesn't rely on it for the tension, as they're usually stuck in the bore anyway.
- The proportioning valve not being pushed in all the way would be a valid explanation for leaking around the sensor.
- Copper colored breather - Ya got me there. Without looking at my car, I'm not sure what you mean. Though there shouldn't be any brake fluid on the outside of the master.
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
yup, there is a copper colored circular thing about a third of an inch in diameter on the bottom of the master. I'll try to snap a photo over the weekend.
- No, it shouldn't leak with the sensor removed.
- I have no idea why that end cap spring is weak. My guess is the prop valve doesn't rely on it for the tension, as they're usually stuck in the bore anyway.
- The proportioning valve not being pushed in all the way would be a valid explanation for leaking around the sensor.
- Copper colored breather - Ya got me there. Without looking at my car, I'm not sure what you mean. Though there shouldn't be any brake fluid on the outside of the master.
- I have no idea why that end cap spring is weak. My guess is the prop valve doesn't rely on it for the tension, as they're usually stuck in the bore anyway.
- The proportioning valve not being pushed in all the way would be a valid explanation for leaking around the sensor.
- Copper colored breather - Ya got me there. Without looking at my car, I'm not sure what you mean. Though there shouldn't be any brake fluid on the outside of the master.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Mate im sorry for giving you potentially false info there, i answered from my personal experience. It did actually fix the leak on my 87, but then i only had it another 3 weeks after that too.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Maybe it's there to complete the ground circuit. Otherwise the Orings will electrically isolate the combination valve from the m/c.
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Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 3,277
Likes: 32
From: Mission Viejo California
hi guys. Here's an update on the leak. The oring on the assembly that the drm spring is in partially got pushed off when the assembly got pushed into the master. So, I have the leaks fixed.
However now I have a spongy peddal. Check out the new thread on the master cylinder from hell....
http://forums.corvetteforum.com/show...post1560697783
However now I have a spongy peddal. Check out the new thread on the master cylinder from hell....
http://forums.corvetteforum.com/show...post1560697783
