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-   -   Brake pedal goes to floor after 4 day sit. (http://www.hotrodders.com/forum/brake-pedal-goes-floor-after-4-day-sit-152953.html)

weirdbeard 02-08-2009 02:35 PM

Brake pedal goes to floor after 4 day sit.
 
I got back from a trip yesterday and started my 98 Yukon after 4 days of not driving it. It started fine, but when I tried to use the brakes the dang pedal sank to the floor and the brake light came on the dash for a second.

I got it home and this morning inspected and bled the brakes. Its better, but still not right at all.
The master cylinder is only about a year old. I don't see any leaks.

What could cause this? :confused:

Henry Highrise 02-08-2009 02:53 PM

Sounds like the master cylinder has gone bad...it is bypassing around the piston. Get a new master cyl. Bench bleed it and install it and bleed your brakes and you should be good to go.

weirdbeard 02-08-2009 02:59 PM

That's what I am thinking too HH. Just don't seem right cuz the M.C. is so new, but I did get it from Advance. :rolleyes:

Bryan59EC 02-08-2009 03:06 PM

Went thru about 4 of these things in the 80s on my 79.
Silly brakes only worked when they wanted to.
Scary feeling when the pedal goes to the floor, eh?

Must have got a good one last time around----still working like it shoud.

weirdbeard 02-09-2009 03:55 PM

I pulled the M.C. off today and there was brake fluid behind it! I installed another one and it seems fine for now.

It really makes me mad that they can't make these parts last longer than a year.
Just ain't right. :rolleyes:

weirdbeard 02-09-2009 03:58 PM

Oh yeah Bryan it is a scary feeling when that brake pedal sinks to the floor! My heart sinks with it every time. :eek:

eloc431962 02-09-2009 04:11 PM

i agree with Henry.i have had it happen to me .and seen it on others also.m c goes bad bypassing to the booster.good call henry. :thumbup:

flynbrian48 02-09-2009 04:48 PM

Quote:

Originally Posted by eloc431962
i agree with Henry.i have had it happen to me .and seen it on others also.m c goes bad bypassing to the booster.good call henry. :thumbup:

Brake fluid can ruin the booster too, so forewarned is forarmed!

weirdbeard 02-09-2009 04:55 PM

Quote:

Originally Posted by flynbrian48
Brake fluid can ruin the booster too, so forewarned is forarmed!

Dang! I did not even think to clean that old fluid up behind the M,C!
Now I am just imagining it corroding my dang booster..

Maybe I will just try and spray some wd-40 back there. :rolleyes:

Cape Cod Bob 02-09-2009 05:36 PM

I haven't had one apart since they were singles, but we used to just put in a new "O" ring. Maybe a little honing if needed. Much cheaper. :cool:

weirdbeard 02-09-2009 06:31 PM

Quote:

Originally Posted by Cape Cod Bob
I haven't had one apart since they were singles, but we used to just put in a new "O" ring. Maybe a little honing if needed. Much cheaper. :cool:

I was thinking about taking this one apart to see what the heck happened during that 4 day sit.. I might just rebuild it for the practice.. Never tried that before. ;)

Henry Highrise 02-09-2009 06:38 PM

I have over the years re-built master cylinders as well as wheel cylinders. Just clean them up, hone them out, and replace the rubber cups or O rings etc. I found they did not hold up like mew ones. But then I got to thinking about it....You do take off some metal honing and increase the bore size just a tad. The rubber parts are still standard size not oversized a tad to compensate. I then quit doing it....brakes are just too important to play around with. Even the rebuilt parts. I always buy new parts and I like the name brand stuff like Wagner, etc. It might cost more but it could save your life or somebody elses.

blyne3 02-15-2009 08:17 PM

Do Not Hone An Aluminum Master Cylinder!


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