Another Brake Problem

[GNJOE]

I have a strange brake fluid problem. Parked the car the other day and checked it a day later. Everything looked fine. Today, 2 days later I see a pool of brake fluid under the car. I am having a problem with the rear brakes hanging up (they are original. Car only has 48K miles) but this is strange. I opened the reservoir and it was full to the top, it looks like it overflowed. When I park the car I disconnet the battery (it sits for weeks at a time) so I know nothing was powered that could have caused the preasure to build. It looks like the fluid came from the reservior, but it is full? I might note it has been very hot here and the garage was 100+ but could that cause the system to overflow or is the problem with the rear brake hanging up some how related? The car is going in to the dealer to have the brakes checked out Friday but this was for the problem of them hanging up not the fluid leak problem. Any ideas what could cause this?


87 Gn stock. 48k Miles.

 

[John Larkin]

So the brake reservior is overflowing? If this is a PowerMaster, one side is supposed to be low (I think the inboard side) and the other side full. If you've topped them off, then this could be the reason.

For the brakes hanging, a little more info would be good. However, I have experienced on a front caliper a soft hose which would collapse and not allow the caliper to release. Perhaps this is happening with your rear hose (the one from the frame to the axle).

 

[GNJOE]

Thank you for the information John.
I did not know 1 side was suppost to be low. Yes I did top it off but this was a 100 miles or so ago. Would it take that long before it overflowed and after the car has been sitting for 2 days?
As for the brakes hanging up they do it after they get warmed up. When I hit the gas I can hear a noise from the rear brakes and the car seems to hold back. If I stop easy and then take off again there is no problem. It feels like the brakes are letting go but then then grab again until I speed up more.
The car does sit alot. I put less than 300 miles a year on it.

 

[tim87tr]

My GN just did the same thing and I don't remember the last time filling up the reservoir. Had a lot of fluid on the floor after it was parked and determined it came out the engine side of the resevoir. Going to change the brake fluid in the car anyway. Just read an article about how to do this, and prevent the old dirty fluid from traveling back into the master cylinder, which hurts the seals in it.

And, this may not be exact, but I have done this before on other vehicles after a mechanic told me, and it could not hurt.......drive the car in reverse and use the brakes to self-adjust them. Maybe it does not work on these cars. I have the rear brakes and cylinders off my T to do some work, and hopefully I'll know more about brake systems in a couple weeks . I was going to use that brake system bleeding procedure on gnttype.org also if you want to check that out. Tim

 

[John Larkin]

If your rear shoes have never been adjusted, then it's likely they need it. The backing plates have knock outs just behind the lower shock mounting point that are likely still in place. There are two. Remove the wheel and drum and see which one would give you outside access to the star adjuster. Then knock that one out, not both of them. Once wheel and drum are reinstalled, leave the rear end up and tires off the ground, car in neutral. Tighten the star adjusters until the wheel locks up from turning it by hand. Then loosen the star adjuster 3-4 clicks/teeth; you'll see what I mean. That should be a good setting. You'll get alot of drag from the driveline and the rearend but they should be able to be spun by hand with a good push approx. 1/2 turn. I'm still suspicious of that rear hose if this doesn't help. When they go soft, they compromise the hydraulic effect of the braking system by collapsing internally and not allowing proper fluid flow in both directions.

Also make sure all the brake hardware is installed properly, i.e. springs, clips, shoe retainers, and that nothing is in a bind before putting the drum back on. If you don't feel comfortable with how they are operating after putzing around with it, then by all means take it to a professional; brakes aren't good candidates for a best guess. Luckily, this is one thing that isn't so exotic on our cars.