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When I start the Vette cold and back it out to warm up, the brake pedal does not come back to home and brake lights are on. I have to pull it back up to get it home. The problem subsides when it has gotten to temp.
Not a big issue, it think, but I cannot help wondering why this is starting to happen and if it is a symptom of a larger pending issue.
I do get a small amount of fluid on my garage mat. Not a lot but over time its there. Whould that be where its coming from? Possibly a small leak somewhere in the braking system?
I think Bob K is on the right track with the master cylinder. There are 2 springs in there that return the pistons to their rearward non-braking position. If one or both pistons are hanging up on some rust or sludge it wouldn't push back on the pedal. If the rear seal is breaking down, it will leak out the rear. Wipe your fingers under the mounting flange at the firewall or brake booster.
When was the last time the system was flushed (if using DOT 3 or 4)?
It was totally rebuilt 4 years ago. Not that many miles since maybe 1000. There are two grease fittings on the master, could it use a bit of lube? Sorry my knowledge of all of this is slim....
I will follow your advice tomorrow to see if something is coming out the back.
It was totally rebuilt 4 years ago. Not that many miles since maybe 1000. There are two grease fittings on the master, could it use a bit of lube? Sorry my knowledge of all of this is slim....
I will follow your advice tomorrow to see if something is coming out the back.
Best,
Hans
Those aren’t grease fittings. They are bleeders. If you inject grease, you will be rebuilding that master cylinder.
I guess my real question here is. Is what I am facing right now worth putting it in the shop which would amount to the rest of the summer, or is it not serious enough that it can wait until winter service???
Those aren’t grease fittings. They are bleeders. If you inject grease, you will be rebuilding that master cylinder.
Originally Posted by HCK
Here are the fittings I was thinking of. So these are bleeders?
Originally Posted by HCK
I guess my real question here is. Is what I am facing right now worth putting it in the shop which would amount to the rest of the summer, or is it not serious enough that it can wait until winter service???
Yes, those are bleeders to purge the air from the master. Many replacements did away with them, but Corvettes had them from the factory.
As far as delaying fixing it, I feel it comes down to a safety issue. As long as you feel it's drivable without compromising your focus or ability to drive the car safely, it's up to you.
Have you tried working the pedal all the way down and up a number of times to see if it frees up whatever is causing it to not return on its own? Maybe you could use the bleeders to assist you in clearing out the piston bores: hook up two hoses with the open ends below the fluid level in the reservoirs. Open the bleeders and work the pedal – you'll be pushing the fluid out and back to the top. If that doesn't work, you'll be looking at a master rebuild (which is simple) or a master swap, both of which will require a full system bleed.
Yes, those are bleeders to purge the air from the master. Many replacements did away with them, but Corvettes had them from the factory.
As far as delaying fixing it, I feel it comes down to a safety issue. As long as you feel it's drivable without compromising your focus or ability to drive the car safely, it's up to you.
Have you tried working the pedal all the way down and up a number of times to see if it frees up whatever is causing it to not return on its own? Maybe you could use the bleeders to assist you in clearing out the piston bores: hook up two hoses with the open ends below the fluid level in the reservoirs. Open the bleeders and work the pedal – you'll be pushing the fluid out and back to the top. If that doesn't work, you'll be looking at a master rebuild (which is simple) or a master swap, both of which will require a full system bleed.
Thanks for the advice.
I will give your suggestion a shot and see if I can remedy it myself. I think given that it is only an issue until the car warms up - does not happen while driving, it resolves once the car is up to temp, and the brakes work fine IMO. I think for now its ok. Lets see if I can get it solved....
Those aren’t grease fittings. They are bleeders. If you inject grease, you will be rebuilding that master cylinder.
And cleaning the entire "contaminated" brake system.
Those bleeder screws are only on certain year models. For GM to stop that MC design means it did not work well or something better came along.
Rumor was, they were used on the assembly line for speed bleeding.
I will give your suggestion a shot and see if I can remedy it myself. I think given that it is only an issue until the car warms up - does not happen while driving, it resolves once the car is up to temp, and the brakes work fine IMO. I think for now its ok. Lets see if I can get it solved....
Best,
Hans
I missed that part about it going away as the car warms. That's a head scratcher... What in the pedal to master would be affected by temperature or run-time changes?
In your pics, there's no booster vacuum hooked up. Are you driving with no booster or was that an in-process pic?
If the booster is hooked up, where is the vacuum coming from on your engine?
I missed that part about it going away as the car warms. That's a head scratcher... What in the pedal to master would be affected by temperature or run-time changes?
In your pics, there's no booster vacuum hooked up. Are you driving with no booster or was that an in-process pic?
If the booster is hooked up, where is the vacuum coming from on your engine?
so the first picture is when the rebuild was going on so not yet hooked up. The second Pic is installed, but a tight shot. There is vacuum hooked up....
it's a 69 427. I need to look at the route of the vacuum hose
so the first picture is when the rebuild was going on so not yet hooked up. The second Pic is installed, but a tight shot. There is vacuum hooked up....
it's a 69 427. I need to look at the route of the vacuum hose
I'm thinking about the booster playing a role. You could pull the master away from the booster and, when cold, see if the pedal issue exists without it in place.
It's a really, really long shot looking at the vacuum source that could, for some odd reason, change as the temps of the engine rise.
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Your booster is going bad. I had the exact same issue. Replace the booster and the master as a set. If you don't get the correct spacing in the pushrod between the two, or they are incompatible you will be forever chasing issues. Do it right, doit once..
I replaced mine with a tuffstuff one 4 or 5 years ago....been great. If you go with them make sure the year is correct and it's for disc/disc. They sell for c2s as well that had drum/drum and drum/disc so that
Your booster is going bad. I had the exact same issue. Replace the booster and the master as a set. If you don't get the correct spacing in the pushrod between the two, or they are incompatible you will be forever chasing issues. Do it right, doit once..
I replaced mine with a tuffstuff one 4 or 5 years ago....been great. If you go with them make sure the year is correct and it's for disc/disc. They sell for c2s as well that had drum/drum and drum/disc so that
Thanks for the reply. I did post the model and engine size in an earlier message but it was buried a bit (sorry) its a 69 427 390 4 Speed. Since I would not attempt this on my own, it sounds like its time for a trip to the shop. I suspect, from your answer you believe this is urgent and should be done now.
I'm really just shooting in the dark here. I see Rescue Rogers replied with direct experience.
If you want to continue testing: Just remove the two mounting nuts from the MC/booster and pull the M/C away a couple inches. (Make sure the cap is secured by the bails so you don't slop out any brake fluid.) This will also allow you to see if the rear of the master is leaking. (Don't screw or unscrew the booster's push rod unless you have a way of resetting the gap to your master.)
Brake Pedal Misbehaving
