I can't seem to get an answer locally, so, here goes: I have brake fluid leaking from the saftey switch on the master cylinder. If you unplug the connector and step on the brakes, fluid shoots right out. Do I need a new switch, or a new (rebuilt) master? Any help would be appreciated.

 

If it's leaking through the body of the switch and not the fitting that the switch screws in to then I think you'd be OK with a new switch.

 

No, A new switch will still leak. Your proportioning valve has moved to a position in which fluid can flow through the switch. You need to either get a new/rebuilt MC or recenter your proportioning valve. That leaking plastic switch is not designed to hold back brake fluid.
The proportioning valve is designed to shut off fluid outlet to the front or rear brakes in the event of a leaking caliper. Now, that switch is spring loaded and presses against the proportioning valve(which is a cylindrical metal bar). If the proportioning valve moves to much one way or the other, the end of the valve(metal bar) is exposed and the spring loaded switch extends. This extension will close the switch(which goes to ground) and illuminte brake light on dash. If your brake light is not lit up, then chances are that the proportioning valve end is only partially exposed at the switch opening in the MC. This partial exposure lets brake fluid flow through the switch, but has not moved far enough to where the spring loaded switch pops into the MC housing to set off your brake light on the dash. Check all 4 calipers for any leakage.
Make sense ????

Here, I found a pic of the opening where that switch goes into your MC. You can see the end of the proportioning valve on the right which allowed brake fluid into the switch. This particular MC leaked at the switch but did not set off my brake light warning. I suspect you have the same condition. I could have reset the proportioning valve, but I opted to replace my MC since it was original and looked like crap.

 

Sounds like a reasonable explanation. How do I reset the proportioning valve? I intend to replace the master, but would like to drive the car safely until I can track down a new unit( or reuilt). Believe it or not, in the greater Toronto area, population in excess of 6 million people, no one has a new or rebuilt unit on the shelf! I was thinking of getting a new unit from Ecklers sent up. Sound resonable?

 

Since this is related. When you replace the master. Do you screw down that switch last after you are done bench bleeding it, or do you put the switch on first thing? Or does it not matter?

 

screw it in when it is on the bench. Although it doesn't really matter, it is easier to get to when the MC is off the car.

 

I haven't done this myself, but others have. Dayum, and I was considering moving to Toronto a few months back for a job opportunity.. If I can't get vette parts though... I am staying here !!
Ecklers is pretty expensive on all their parts, you could do better on ebay, or maybe try corvette central.

For a detailed explanation, check out post #6 in the following thread :

http://forums.corvetteforum.com/c4-t...e-leaking.html

 

That does make sense. As with it off the car, the brake lines won't be in the way. Since it is plastic, it looks like you just get it snug.

 

Thanks for the link; this explains a few things. I removed the end plug and cycled the piston 20-30 times, and this seems to have cured the problem. I'll have to road test it tomorrow to see if it holds up. Ordering a new master anyways. For the money, I'd rather be safe.

Toronto area is a great place, with some great 'vette shops, but I guess these masters don't fail enough to warrent keeping rebuilts on the shelf. Oh, and of course we have Canadian beer, free health care, pole dancers, and hockey! Beauty, eh!

 

What brand master cylinder are you planning on getting?

 

I got one from the Autozone. New switch was installed as were the reservoirs.

 

I was thinking of getting the new unit gtom Corvette Central.

 

Exactly . Or the seal/boot on the proportioning valve may be bad.

 

OK, I have the master cylinder working, a rebuilt is on the way , as well. I replaced the vacuum lines that run under the master because they were soaked with brake fluid and spongey. Only problem, I broke the connector off the small diaphram valve beside the rear of the intake. It feeds vacuum to the cruise control, plus a small line that funs behind the distributor, and another larger lline that runs through the intake runners. Can anyone tell me what this unit is called, and what does it operate? Are these available?

 

I forget exactly what it's called. Something like vacuum canister check valve or something. They're pretty common and you should be able to get one at any parts store. I'm pretty sure Dorman, the red blister pack HELP products makes them.

 

Thank you. I found them at Corvette Central, and Corvette Parts Man.com. They call it a 'vacuum resevoir check valve', $7.00. Cheapest part I'll ever buy for the car!

 

These vacumm check valves are very common on many GM cars. You can pick one up at pep boys, autozone, Napa or almost any parts store in the "Help" section...... 4 or 5 bucks...

Pole dancers ehhhhh !!!!!!!! I like that !!

 

I'd get that part from the dealer. I recall it being cheaper than the knock off one at Autozone. I've had the ones from Autozone brake off even though they were fairly new.

 

I did that, GM had them in the warehouse, next day delivery.
Thanks for your help, everyone.

 

For future reference, you can get a lot of parts for your 'Vette (including some discontinued items) from CarQuest Auto Parts. There are a number of locations around the GTA, and they can usually get 'non-stocked' items within a day.

And for the record, you can FORGET any store/shop/dealer in the GTA carrying Corvette parts in inventory. Except for "regular" items like plug wire sets, air filters, oil filters, spark plugs, and light bulbs it is almost impossible to find Corvette parts on the shelf anywhere.