either leak or air. Jack er up and look for wet spots. If none, then bleeding should help in the short term but you'll probably have to take care of the brake cylinders in the longer term.
Brake light in dash
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Brake light in dash
I just put the insurance back on my 73 and have had a couple of drives and was doing a little checking under the hood.Checked the master cyl and front side was down but not out so I topped it off.
Brakes were working OK.
Today I noticed the dash brake light was on just after I started it up and I was backing up so I pumped the brakes a few times and the light went out and the pressure came back. I was driving slow and the light came on again so I pumped them again several times and again the light went out and the pressure stayed up this time. It stops but I think the pedal is not as hard as it has been in the past. This could be my imagination.
When I hold pedal down hard it does not seem to go down but it is low on the floor.
I took my flash light and looked through the holes in the rally wheels at all of the calipers and they all look dry. I also pulled the vacuum line from the booster when the engine was running and there is a lot of vacuum.
Any Ideas??? Does this sound like the master cyl is leaking internally?? It will be a week before I can Jack it up all the way around and start looking for other leaks.
Thanks
Race Director
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From: Foxfield CO 1970 Convertible
Sounds like you have a slow leak somewhere. Check under the car again and look at the inside of the tires on the other side of the car for possible small drips. Although the MC could be going, the brake light indicates a differential in pressure between the front and back brake lines. Low fluid in front might point to a leak in the front segment of the system.
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From: Wellington, FL
St. Jude Donor '11 thru '25
With one of the resevoirs down, you must have a leak somewhere as the fluid had to go somewhere. As others are saying, check the MC and calipers for leakage. One other thing, I've always read and heard that when we let our Vettes sit for extended periods of time, it is always a good idea to get in and just pump the brake pedal a few times to move the pistons and seals. This is supposed to help prevent premature caliper leakage. Good luck.
Le Mans Master
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From: Ann Arbor Michigan
Originally Posted by wombvette
There is air the lines. Bleed them.
Le Mans Master
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From: New Hill NC
I agree with that Duke, but he said the MC held, and I am taking him at his word on that. I also agree that obviously there is a leak somewhere for the fluid to get down. But his original question was how to get rid of the soft pedal and get rid of the light. Bleeding will do both. Then he can fnd the source of the original problem.
Last edited by wombvette; Nov 5, 2006 at 10:00 AM.
Le Mans Master
Joined: Mar 2001
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From: Ann Arbor Michigan
Originally Posted by wombvette
I agree with that Duke, but he said the MC held, and I am taking him at his word on that. I also agree that obviously there is a leak somewhere for the fluid to get down. But his original question was how to get rid of the soft pedal and get rid of the light. Bleeding will do both. Then he can fnd the source of the original problem.
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Thanks - some good thoughts. Tonight just after work I shined a flash light under the back side of the front tires and didn't see any wet on the rims or tires. It is the front sestion of the Master cyl and I think that is for the front brakes. Then started it and did the slow pump and hold and it seemed to hold and did the hard pump and hold and it seemed to hold. No light tonight but I didn't drive it either.
What I am wondering is since the brake fluid is Old - no idea just how old if it is possible for it to have just heated up from use and boiled water off leaving it low??? I suppose it is also possibloe that the lowness of the fluid is because of pad wear. Still doesn't answer the light issue which I understand is pressure differential between the front and rear
I'll for sure jack it up , put the jack stands under it and look all the lines over to see if I can find a leak and go ahead and change the fluid and bleed them all to see if that helps. Look at the pads for wear and see what else I can find.
Any recommendations for a reasonable place to get stainless brake hoses?
Thanks again. LBM
What I am wondering is since the brake fluid is Old - no idea just how old if it is possible for it to have just heated up from use and boiled water off leaving it low??? I suppose it is also possibloe that the lowness of the fluid is because of pad wear. Still doesn't answer the light issue which I understand is pressure differential between the front and rear
I'll for sure jack it up , put the jack stands under it and look all the lines over to see if I can find a leak and go ahead and change the fluid and bleed them all to see if that helps. Look at the pads for wear and see what else I can find.
Any recommendations for a reasonable place to get stainless brake hoses?
Thanks again. LBM
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I decided to just go ahead and change the brake hoses since they are most likely 32 years old , change the brake fluid and of course bleed the brakes.
Oddly enough I only had the brake light issue twice on the same day on the way home from work. The only thing I did then was pump the brakes several times and hit them hard a couple of times to make sure they would stop me on the way home. Car has sat for 4-5 days with out running with the exception of the one night I started it up and did the slow brake pedal test.
Today I took it for a couple of hundred mile run looking for brake hoses and just going for a drive around NW Arizona and had no problem -although it did seem to get a harder pedal if I pumped them once - more then once didn't seem to be any difference then one pump.
No doubt there is air in the lines but it seems odd that the brake pressure deferential light came on twice - I did turn up the Idle a little but I doubt that had anything to do with it.
Anyway Tomorrow I will do the front brake hoses, fluid change and bleed and be rolling down the road.
Thanks again for the help.
LBM
Oddly enough I only had the brake light issue twice on the same day on the way home from work. The only thing I did then was pump the brakes several times and hit them hard a couple of times to make sure they would stop me on the way home. Car has sat for 4-5 days with out running with the exception of the one night I started it up and did the slow brake pedal test.
Today I took it for a couple of hundred mile run looking for brake hoses and just going for a drive around NW Arizona and had no problem -although it did seem to get a harder pedal if I pumped them once - more then once didn't seem to be any difference then one pump.
No doubt there is air in the lines but it seems odd that the brake pressure deferential light came on twice - I did turn up the Idle a little but I doubt that had anything to do with it.
Anyway Tomorrow I will do the front brake hoses, fluid change and bleed and be rolling down the road.
Thanks again for the help.
LBM
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From: Buckeye, AZ
St. Jude Donor '12-'13
I had an issue with my m/c where you would hit the pedal one time and it would go soft; immediately let off and repress and it was hard. the final outcome was that the gasket on the m/c piston was old and deformed as well as there was a great deal of sludge in the bottom of the m/c, so i was getting blow by at times. I rebuilt the unit (to keep numbers), bench bled, system bled and the pedal has never gone soft again. Make sure you us Vette bleed sequence not general car sequence. Also if the brake light is on you can clear it by depressing the brake pedal down as hard as you can for about 3 seconds or so. You will feel a kind of blip and then the light will clear.
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OK what is the vette sequence for bleeding brakes - is there an old thread on it. Actually never thought about sequencies. I have a set of stainless brake hoses on order so I'll change all 4 of them out and then bleed them.
