Hard to Press Brake Pedal - 1996 F250 7.3l Diesel Turbo

Thank you for the chance to try to finally resolve this continuing problem. My truck is experiencing a hard to press brake pedal. It comes and goes and does not seem to happen at any one time while driving. I know that my truck uses a vacuum pump and instantly replaced this as I figured that with the age of the truck it should be done. However even with a new vacuum pump it did nothing to correct my problem with a hard to press brake pedal. I inspected all the lines to ensure that they are holding pressure and replaced two of the three with new lines. Again it still did nothing to correct the issue. I do not have any leakage coming from the master cylinder and no hiding noise from the brake booster.

As always, love your show and hope that you can impart your wisdom my way.

Thanks again


1996 F250 7.3l Diesel Turbo
270,000 miles
Manual Transmission

Get as near as possible to the brake pedal and with the engine running listen for a vacuum leak at the brake push rod when the brake pedal is pressed.

I would venture to believe that on a diesel is hydroboost instead of vacuum booster. Check your power steering fluid.

The OP has replaced the vacuum pump, pete.