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90 GMC safari dissappearing brake fluid

billprasad's Avatar

Join Date: May 2001
Posts: 20

07-08-04, 11:09 AM   #1  
90 GMC safari dissappearing brake fluid

Good Day,

I have a mystery on my hands. Old faithful (my safari) is loosing brake fluid. By loosing I mean it just dissappears. The smaller reservoir on the master cylinder goes down by half in a month and a half. I see no signs of leakage anywhere. I have opened up the drums and checked the wheel cylinders, dry. I have checked the front calipers, dry. I have checked around the master cylinder, dry. I have looked at the lines below the vehicle, dry. I have loosened the master cylinder to see if there was a leak between the master and the booster, dry. I am wondering if the abs "box" is sucking in brake fluid because it is thirsty.

Any ideas as to where I should look next for the dissappearing fluid would be greately appreciated.

thank you in advance for your wise advise


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michael van's Avatar

Join Date: Nov 2001
Posts: 2,345

07-08-04, 02:35 PM   #2  
check this

Rub your hand were the brake rod comes thru the fire wall (inside).
Rub the carpet and smell your hand for the smell of brake fluid.

Johnc280's Avatar
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07-09-04, 06:00 PM   #3  
Your Engine could be burning it.

Michael is a little on the right track. Only if it is leaking out the back of the M/C it will not go into the car through the firewall because of the booster, but it certainly could be inside the booster. And therefore your engine could be sucking it in through the vacuum supply line. Pull off the check valve from the booster and see if there is any fluid inside the booster or hose.

Hope this Helps.


billprasad's Avatar

Join Date: May 2001
Posts: 20

07-23-04, 09:37 AM   #4  
No luck, both dry

Hello Gents,

I checked both the booster, and the carpet both dry.

thanks for the suggestions.

davo's Avatar

Join Date: Apr 2002
Posts: 2,417

07-23-04, 02:25 PM   #5  
If you drive alot it may be due to front brake pad wear.See if the pads are getting worn down.The small resivour bleeds over into the larger one so if the large one lowers due to pad wear so does the small one.

EARLS's Avatar
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07-24-04, 01:14 PM   #6  
Brake Fluid Loss

That Is Totally False, Brake Fluid Should Not Transfer From One Side Of Reservoir To The Other, If It Does What Is The Purpose Of A Dual Reserve System. It Is There For That Exact Reason, To Allow You To Have Back Up Brakes In The Even Of A Leak. Replace The Master Cylinder.

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