The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - How do you tell if a Brake Combination Valve is Defective?

71/454 · 01-18-2006, 02:19 AM

Just my 2 cents but, I had an 81 do this same thing, you practically had to stand on the pedal to make it work. I went thru and changed a bunch of stuff and ended up living with it. I sold the truck to a friend who drove it into the ground and never cared to fix anything. I ended up buying it back a year or two later and as soon as I drove it I knew it needed a booster. I guess it was just slowly on it's way out when I had it and he could have cared less. When I was trying to diagnose it, it still held vacum if u pulled off the hose and the pedal sunk when u started it. I guess I'm trying to say maybe it's the booster, you never can tell seems like!

01-18-2006, 02:19 AM	#2
71/454 Turbo Guy Join Date: Jan 2005 Location: Calgary Alberta Posts: 353	Re: How do you tell if a Brake Combination Valve is Defective? Just my 2 cents but, I had an 81 do this same thing, you practically had to stand on the pedal to make it work. I went thru and changed a bunch of stuff and ended up living with it. I sold the truck to a friend who drove it into the ground and never cared to fix anything. I ended up buying it back a year or two later and as soon as I drove it I knew it needed a booster. I guess it was just slowly on it's way out when I had it and he could have cared less. When I was trying to diagnose it, it still held vacum if u pulled off the hose and the pedal sunk when u started it. I guess I'm trying to say maybe it's the booster, you never can tell seems like!