Brake issues - lost brakes, but no leaks found? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

InNeedofaDelorean · 04-30-2018, 11:29 AM

So I recently bought a 1967 GMC 3/4 2wd, and I lost brakes on my way to work. It's in the shop, and they refilled the brake fluid and found no leaks - none of the lines are leaking, and we're all scratching our heads as to where it leaked from, or where it went. I know there was a bunch of fluid dripping from the transmission pan, and from other parts near that area, so there is a leak somewhere, or something burst at 60mph and isn't doing it right now. Any ideas? I'd like to be able to drive it without dying, haha.

Bigdav160 · 04-30-2018, 11:37 AM

Manual brakes or power? Inside on the floor or in the booster.

Did you pull all four wheels and poke around with your fingers under the wheel cylinder dust boots?

davepl · 04-30-2018, 11:38 AM

Flex line that only leaks when pulled in one direction? No idea, should be obvious under pressure though! Rear wheel cylinders would be somewhere else a leak could hide, but you've got fluid up front.

InNeedofaDelorean · 04-30-2018, 11:45 AM

It's really wacky. They're going to be checking the master and the booster today, and rebuilding the entire rear brakes as well, as they locked up. I'll tell them to mess around with the flex lines.

It has power brakes, disc front, drum back.

04-30-2018, 11:29 AM	#1
InNeedofaDelorean Registered User Join Date: Oct 2007 Location: Raytown, Missouri Posts: 130	Brake issues - lost brakes, but no leaks found? So I recently bought a 1967 GMC 3/4 2wd, and I lost brakes on my way to work. It's in the shop, and they refilled the brake fluid and found no leaks - none of the lines are leaking, and we're all scratching our heads as to where it leaked from, or where it went. I know there was a bunch of fluid dripping from the transmission pan, and from other parts near that area, so there is a leak somewhere, or something burst at 60mph and isn't doing it right now. Any ideas? I'd like to be able to drive it without dying, haha.

04-30-2018, 11:37 AM	#2
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: Brake issues - lost brakes, but no leaks found? Manual brakes or power? Inside on the floor or in the booster. Did you pull all four wheels and poke around with your fingers under the wheel cylinder dust boots? __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

04-30-2018, 11:38 AM	#3
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: Brake issues - lost brakes, but no leaks found? Flex line that only leaks when pulled in one direction? No idea, should be obvious under pressure though! Rear wheel cylinders would be somewhere else a leak could hide, but you've got fluid up front. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

04-30-2018, 11:45 AM	#4
InNeedofaDelorean Registered User Join Date: Oct 2007 Location: Raytown, Missouri Posts: 130	Re: Brake issues - lost brakes, but no leaks found? It's really wacky. They're going to be checking the master and the booster today, and rebuilding the entire rear brakes as well, as they locked up. I'll tell them to mess around with the flex lines. It has power brakes, disc front, drum back. Last edited by InNeedofaDelorean; 04-30-2018 at 12:19 PM.



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