| Re: [GMCnet] Brakes going soft - How long to wait / What to do? [message #322213 is a reply to message #322203] |
Wed, 16 August 2017 16:33   |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma:
|
Senior Member |
|
|
Peer Oliver Schmidt wrote on Wed, 16 August 2017 16:37We have made it down to Highland, CA and are sitting now in the AutoZone parking lot.
I am still open for ideas. I don't see any fluid near the brakes. atm I can't get the top of the master brake cylinder off, but eventually will succeed.
Is there a way to determine what DOT (3,4,5) I should use, if I need to fill up? Open for all hints, tips, tricks, and suggestions 
Peer,
The DOT number of the brake fluid is substantially its boiling temperature.
If the fluid it purple (or blue depending on your vision), then it is DOT 5. Hope it is not as it is incompatible with everything. This is unlikely as it is way more expensive than either DOT 3 or 4.
You are in a Autozone lot, they sell a Valvoline DOT 3&4, you can't go wrong with that.
The things inside the master cylinder cover are just diaphragms to allow the fluid level to change with introducing air and the associated moisture.
When you say that the brakes where non-existent, was there just little or no effect or did the pedal go to the floor. These two are very different cases:
=> The brakes had less effect => That is fade, it is common to all brakes but worse for drum brakes because the drum expands away from the shoes faster than the system can accommodate. If this is the case, the brakes will be good as they were before once they have cooled.
=> The pedal went to the floor and you heart went into your throat. This is a boiling brake fluid case. Brake fluids are highly hydroscopic (they soak up water) and the water depresses the boiling point. If this is what happened, you can drive it once it is cool, but it is advised that you get the brake system flushed with new fluid as soon as you possibly can.
In both cases, it is unlikely that the brake parts were actually damaged. Therefore, cooling and maybe new fluid should do it.
Water gets into brake fluid two ways. One is around the cylinder and piston seals, it actually gets pulled in there a molecule at a time over long periods. The other way that rubber gasket/diaphragm in the top of the reservoir, they get bad with time just like all the other rubber. They are usually available on the parts pins at auto parts stores.
Am sure am glad that you are at the bottom of the hill and telling us this.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
