[tld]

I have a 1985 ccd and for some reason when i press on the brake it stops good but if i hit them again i only have back brakes? Do i have a problem with my proportion valve? I put a 401 ford diesel in it which is about 400-500lbs heavier, would that have much to do with this problem? Thanks Terry

 

[cdnsarguy]

Do a vacuum test on my gallery........see if the vac pump is working right first.

 

[Mitchalvin]

Check your master cylinder my truck had a similar problem where if I stopped and had to use the brakes shortly afterward had almost no braking. When stopped my pedal would creep down to the floor. Pumping my brakes resulted in less effectiveness after every pump.