Master Cyl. reservior leaking... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**COBALT** · 12-12-2003, 11:23 AM

My master cylinder is leaking. It looks like I have brake fluid running down behind the reservior and proportioning valve all over the bottom of the brake booster (power brakes). Yesterday I smelled burning brake fluid, so it's getting on the exhaust manifold. I checked the reservior, and the rear one was empty! oops.

Pretty simple fix? My brakes need work anyway, so I figured I'd get in there and replace whatever I need to replace. I assume there's a gasket behind the reservior, and the fittings to the proportioning valve probably need to be looked at. I've never messed with these brakes besides new shoes, so any explanation as to what to expect would be helpful. The brake lines are old, but they're not leaking. New brake shoes and wheel cylinders and I think I'll be good to go.

Sound good?

70c10 · 12-12-2003, 12:32 PM

Mine leaks too. Master cylinders are pretty cheap. One more thing on my list!

**old Rusty C10** · 12-12-2003, 01:02 PM

theres no gasket that sits between the master and the booster. you will prolly just have to replace the master cylinder the seal is bad prolly in there. remember to bench bleed it before ya install it then youll have to bleed the lines individially starting fromt he furthest one from the master and working closer

**COBALT** · 12-15-2003, 11:24 AM

Crap. I thought I'd be able to get away with a simple fix. Oh well. It's all rusty and old anyway....

Bench bleed?

**old Rusty C10** · 12-15-2003, 02:10 PM

you bleed the master before ya hook it up to the lines you can do it on the truck but most people do it on the floor or bench hence the term bench bleed steps should be in any decent how to book and some masters come with a bleed kit in em

**COBALT** · 12-17-2003, 05:00 PM

Cool. Thx.

12-12-2003, 11:23 AM	#1
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Master Cyl. reservior leaking... My master cylinder is leaking. It looks like I have brake fluid running down behind the reservior and proportioning valve all over the bottom of the brake booster (power brakes). Yesterday I smelled burning brake fluid, so it's getting on the exhaust manifold. I checked the reservior, and the rear one was empty! oops. Pretty simple fix? My brakes need work anyway, so I figured I'd get in there and replace whatever I need to replace. I assume there's a gasket behind the reservior, and the fittings to the proportioning valve probably need to be looked at. I've never messed with these brakes besides new shoes, so any explanation as to what to expect would be helpful. The brake lines are old, but they're not leaking. New brake shoes and wheel cylinders and I think I'll be good to go. Sound good? __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

12-12-2003, 12:32 PM	#2
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Mine leaks too. Master cylinders are pretty cheap. One more thing on my list! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

12-12-2003, 01:02 PM	#3
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,313	theres no gasket that sits between the master and the booster. you will prolly just have to replace the master cylinder the seal is bad prolly in there. remember to bench bleed it before ya install it then youll have to bleed the lines individially starting fromt he furthest one from the master and working closer __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

12-15-2003, 11:24 AM	#4
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Crap. I thought I'd be able to get away with a simple fix. Oh well. It's all rusty and old anyway.... Bench bleed? __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

12-15-2003, 02:10 PM	#5
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,313	you bleed the master before ya hook it up to the lines you can do it on the truck but most people do it on the floor or bench hence the term bench bleed steps should be in any decent how to book and some masters come with a bleed kit in em __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

12-17-2003, 05:00 PM	#6
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Cool. Thx. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.



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