Brake pedal pulsing/pushing back
rgfritz
01-29-2006, 01:26 PM
When I press on the brake pedal it pushes back at you and sort of pulses. It's not the type of pulsation you get from a warped rotor but actually a push back at you from the pedal. The brakes are working fine otherwise. Any ideas what could cause this? The van is a '98 Astro non-AWD
Kings-x59
01-29-2006, 03:33 PM
This sounds like the brake booster is having issues.
I have a really old astro, on which the booster was of the vacuum type. The later models are hydraulic, working from the power steering pump.
One suggestion is to check your power steering fluid level.
If it's low, add some fluid of course, but more importantly find the leak.
If the fluid level is not low, it's likely that the booster has given up the ghost.
The booster isn't a home repair job without replacing the whole unit, which is not cheap I'm sure. Wait to see if someone else chimes in with some thoughts before running out to buy a new booster.
I have a really old astro, on which the booster was of the vacuum type. The later models are hydraulic, working from the power steering pump.
One suggestion is to check your power steering fluid level.
If it's low, add some fluid of course, but more importantly find the leak.
If the fluid level is not low, it's likely that the booster has given up the ghost.
The booster isn't a home repair job without replacing the whole unit, which is not cheap I'm sure. Wait to see if someone else chimes in with some thoughts before running out to buy a new booster.
dewaynep
01-30-2006, 10:28 AM
Sounds like the ABS is engaging. If it does this on perfectly dry pavement and it is not possible that the wheels are sliding, you have a wheel speed sensor that is bad. Also, if it happens only below about 5-7 mph then it most definately is a malfunctioning wheel speed sensor. I would have your wheel speed sensors checked.
rgfritz
01-31-2006, 04:29 PM
Update:
After carefully driving and braking and paying close attention to the problem here's what I've found. When you apply the brake there is a noticable "catch" at the beginning of pedal travel. This catch can be felt while stopped or moving. At the instant this "catches", there is a very quick and slight pull to the right and the pedal kicks back. After this initial "catch" the pedal is smooth and the brakes work perfectly....no pulling or pulsating at all. Looking under the hood it's evident that there has been power steering fluid forced up thru the cap where it has then ran down the sides of the reservoir. The fluid level was down very slightly (1/8") below the full mark.
Kings-59: This sounds like you're in the ballpark with the problem being in the brake booster. I've read thru the Chiltons and I don't think replacing it will be too bad of a job but I'd like to be sure this is the problem first. Is there a way to diagnose further? Anyone?
Sorry for the long post....just trying to paint a clear picture.
After carefully driving and braking and paying close attention to the problem here's what I've found. When you apply the brake there is a noticable "catch" at the beginning of pedal travel. This catch can be felt while stopped or moving. At the instant this "catches", there is a very quick and slight pull to the right and the pedal kicks back. After this initial "catch" the pedal is smooth and the brakes work perfectly....no pulling or pulsating at all. Looking under the hood it's evident that there has been power steering fluid forced up thru the cap where it has then ran down the sides of the reservoir. The fluid level was down very slightly (1/8") below the full mark.
Kings-59: This sounds like you're in the ballpark with the problem being in the brake booster. I've read thru the Chiltons and I don't think replacing it will be too bad of a job but I'd like to be sure this is the problem first. Is there a way to diagnose further? Anyone?
Sorry for the long post....just trying to paint a clear picture.
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