308QV Brake Issue

andrew,I would post this ????????? in the technical Q&A thread,I think you might get a better reponce,but I'm wondering if it could be in the slave cylinder,

 

Power brake vacuum servo is going, or gone. Been there done that. Also a small chance it may be a leak or faulty check valve in the vacuum line between the engine bay and the brake vacuum servo (check valve is located on the drivers side, just below the ignition coils). Sounds like the vacuum servo to me though, Karp's Brake Service does awesome work, I reccommend them highly.

http://www.resleeve.com/

Whatever the cause, the power assist servo is not receiving or holding enough vacuum.

 

I agree it's a leaky vacuum servo

 

Inspect the check valve and hose first, they fail from age and what he is describing [if he does a search] sounds more like the check valve. I would look at that first before going to the expensive stuff

BTW...I have the same problem, let me know what you find. BTW...if you rev the motor [adding vacuum] quickly the brakes come back...just in case.

 

Agree that you should first check the check valve and vacuum hose from the engine to the front. When I did all my hoses two years ago, the vacuum line was in pretty sad shape. It's a bugger to change, so it is often neglected, even when doing all the others. I had the gas tanks out, so it wasn't bad, but you may find the hose is not in great condition. Remove and clean the check valve and test it as well. If all that is good, then move on to the servo.

 

Would applying a hand vacuum pump to the line going to the front brake servo (connecting it at the engine compartment end) be a good diagnostic procedure? Or are there other lines tapped into this one?

 

If it's the check valve, its probably just dirty. If it's a crack in the hose, that's a local part and or easy fix. You don't want to know a part # for the servo, they are about $1200.00. If you need a servo rebuild, UPS it to Karp's (I don't know your location because your profile is not filled out). Insure it, they are familiar with F-car servos, and pretty quick turn around. Mine was rebuilt there for about $225.00, took less than a week. Solid honest guys.