Brake Booster-Vaccuum Leak

[bvenvert]

I am looking for advice on a vacuum leak associated with the operation of my brakes. I have recently started to experience a braking problem with my 91 Ranger, 4.0L V6 4x4. I took the truck out yesterday and everytime I go to stop the vehicle, I am losing my firm brake pedal. I have had a couple of other issues with Vaccuum in the past, but they were associated with a bad vaccuum modulator on the tranny. I replaced the VM and the tranny has been shifting fine ever since. I have check the vaccuum hose tree on the side of the valve cover and all the connections are still intact. I was wondering if I am missing another connector someone that may have come loose. I guess it could be the brake booster or the master cylinder, but when I have the car in park, I seem to be able to get a firm brake pedal. Any suggestions?

 

[RangerX]

Not saying it's not a vacuum problem, but have you checked for fluid leaks at the wheels, and lines? Checked the resevoir level?

 

[unclemeat]

When I had a similar problem with my X it turned out to be the rubber gromet/seal in the vacumm booster had degraded and cracked. I had to find a similar piece on the HELP isle of the parts store. It solved my problem. I also agree with what RangerX says.

 

[bvenvert]

I have checked the fluid level in the reservior and there has been no drop in the fluid level. I suspect that it is a vaccuum leak in the brake system or a bad master cylinder.

If the master cylinder has gone bad, would the fluid level in the reservior be low? I think it makes more sense that a rubber seal has gone bad in the booster. What do you have to do to replace the seal in the brake booster?

 

[unclemeat]

It is easy to replace. It has been a while but I dont recall it even requiring any special tools. I believe that all the parts are just plain old vacumm hoses and plastic connections. But is does require some soap or other lubricant to easly get everything back together. You may also want to replace the brake vacumm line, real easy.