brake sinks only in hot weather

Just recently, my 1991 Honda Accord has had brake problems. Only when
it is hot out and the car has been in the sun, the brake pedal goes
down to the floor with no appareet brake pad contact. When it cools
down outside, things are fine. I just had the brake fluid changed.
If it is a master cylinder or hose, why would it only happen when it is
hot outside, even when I only drive it for a few miles.

 

I can't think of a time when brake pedal sinking was anything besides the
master cylinder (assuming there was no big leak somewhere.) I bet if you
wrap the master cylinder in cold rags after it starts sinking the sinking
will slow or stop. Or just take the short cut and replace the master
cylinder. If it's the original, it's definitely lived a long life.

Mike

 

master cylinder. some elastomers shrink when warm. time to change.
you can get seal-only kits from majestic honda or replace the whole
cylinder.

 

thanks -- any idea what this will run in $$?

 

wrote in

Most of the local auto parts stores are online,you can check parts
availability and pricing easily.

 

I was losing brake fluid (91 Accord) and the problem was that the
white plastic reservoir that sits on top of the Master Cylinder had a
crack at the bottom. You can't get that part separately, it's only
sold as part of the MC. So I went to the local junkyard and got a used
MC for $40, took the cup off and replaced the cracked one. Works fine.

That, however, left me with an unneeded used MC which is currently
sitting in a plastic bag on the floor of my garage. If you want it
I'll be happy to drop it in the mail. Ill monitor a junk email account
and if you want it just send your address to:

takethebird@(dropthis part out-even junk accounts deserve a
break)hotmail.com

 

Probably a master cylinder. The bore expands as the temperature rises,
so it might be right on the edge. In any case, replace it!

John

 

I'm looking for this kit. My seals are shot. I've looked for it at Sleandro
Honda and Majestic and found none under their listings. Where would it be?

Thanks

 

depends on the vehicle. they're not offered on all models, only the
high volume stuff like 13/16" civics, etc. if majestic don't list it,
you can't get it and whole cylinder is your only option.