HARD BRAKE PEDAL
- Thread starter lunarboy
- Start date
I am pretty sure that you will most likely find that the culprit is the brake booster. It certainly was on the occassions that this same experience happened to me.
If you remove the vacuum hose from the back of the booster, insert a long thin piece of paper straw or similar device into the vacuum chamber angling downwards as you go , you will find brake fluid soaked into the paper.
To correct the problem the booster will require removal and an overhaul.
When was your booster last overhauled? Has the slave cylinder been resleeved in stainless steel?
Ron.
If you remove the vacuum hose from the back of the booster, insert a long thin piece of paper straw or similar device into the vacuum chamber angling downwards as you go , you will find brake fluid soaked into the paper.
To correct the problem the booster will require removal and an overhaul.
When was your booster last overhauled? Has the slave cylinder been resleeved in stainless steel?
Ron.
sdibbers
Well-Known Member
Hey Lunarboy
I would agree with Ron but would suggest a. Ouple of tests to help the diagnosis. First try pumping the brake pedal a few times with the engine off, then hold the pbrake pedal down and start the engine. If the servo/booster is working correctly the pedal should sink a bit as the vacuum augments your foot pressure. If it doesn't it would suggest the servo and vacuum lines have an issue. Second test the vacuum valve on the end of the master cylinder on a 3500 or the valve on the remote servo if you have a four cylinder motor. It should hold a vacuum until the pedal is depressed. You can check this by unsnapping the smallcover on the top of the valve, careful when you do this as there's a srping and filter in there and you don't want to lose them. Once the covers off get someone to depress the pedal while the engines running. You should see the valve stem move in there and re-seat when the pedals released. In very rare circumstances the diaphram may fail in the air valve. If that happens it can stop the servo working. And that is an easy fix compared to pulling and rebuiling the servo. Having said that I think Rons got it on the money.
Good luck anyway,
Steven
I would agree with Ron but would suggest a. Ouple of tests to help the diagnosis. First try pumping the brake pedal a few times with the engine off, then hold the pbrake pedal down and start the engine. If the servo/booster is working correctly the pedal should sink a bit as the vacuum augments your foot pressure. If it doesn't it would suggest the servo and vacuum lines have an issue. Second test the vacuum valve on the end of the master cylinder on a 3500 or the valve on the remote servo if you have a four cylinder motor. It should hold a vacuum until the pedal is depressed. You can check this by unsnapping the smallcover on the top of the valve, careful when you do this as there's a srping and filter in there and you don't want to lose them. Once the covers off get someone to depress the pedal while the engines running. You should see the valve stem move in there and re-seat when the pedals released. In very rare circumstances the diaphram may fail in the air valve. If that happens it can stop the servo working. And that is an easy fix compared to pulling and rebuiling the servo. Having said that I think Rons got it on the money.
Good luck anyway,
Steven
If you service it with a kit check the quality of the bore. They do corrode when the air valve bits enter the bore. The one on my car had failed a while ago and when stipped down it turned out it had been recently serviced with new sills but had failed because of the bore. So I got a fully rebuilt one with new bore insert from Wins.