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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: p7387 on May 31, 2015, 02:48:06 pm

Title: smaller brake reservoir empty
Post by: p7387 on May 31, 2015, 02:48:06 pm

hope this is the correct spot on the forum for brake related issues?

1987 305 2WD short fleet
the front/small brake reservoir keeps depleting completely, in addition the rubber bladder is always partially getting sucked off of the square perimeter of the reservoir itself, is this normal because it never seats nice?

this small reservoir is specifically for the rear brakes correct?
i do not see any obvious signs of leaking, i need to get under the truck and look at the lines

any advice ?
thanks

Title: Re: smaller brake reservoir empty
Post by: zieg85 on May 31, 2015, 03:44:38 pm

If it leaks down slowly it is more than likely one or both of your rear wheel cylinders is seeping.  Yes the small reservoir is for the rear only.  I have also seen the master leak back into the inside of the cab with no power brake set up.

Title: Re: smaller brake reservoir empty
Post by: Irish_Alley on May 31, 2015, 04:27:33 pm

Quote from: zieg85 on May 31, 2015, 03:44:38 pm

If it leaks down slowly it is more than likely one or both of your rear wheel cylinders is seeping.  Yes the small reservoir is for the rear only.  I have also seen the master leak back into the inside of the cab with no power brake set up.

(http://www.naioa.com/v2/modules/Forums/images/smiles/iamwithstupid.gif)
if it was a line problem it would be a sudden lost of brakes so it should be a slow leak. the rubber is supposed to seal but if you are losing fluid the lack of fluid in the reservoir will cause a vacuum and suck the rubber down. 

Title: Re: smaller brake reservoir empty
Post by: p7387 on June 01, 2015, 01:56:36 am

sorry i see i accidentally posted this in the "truck of the month section"
perhaps it will be moved to the appropriate section

if i fill it and drive for just a short while its already empty, and the brakes seem slightly off.
i don't see any obvious leaks but i need to check further

Title: Re: smaller brake reservoir empty
Post by: Jason S on June 01, 2015, 02:27:06 pm

Pull the rear drums off and take a peak inside.

Title: Re: smaller brake reservoir empty
Post by: pneuner750 on June 09, 2015, 07:34:01 pm

Is this manual transmission ?  If so it's  your hydraulic clutch.

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Title: Re: smaller brake reservoir empty
Post by: Irish_Alley on June 09, 2015, 08:58:34 pm

if the wheel cylinders leak they will drip down the rear tires on the inside. you will normally see dirt stuck to the bottom of the backing plate on the inside of the drum