No brake boost when (very) cold - 87 4KQT

[Brendan K. Walsh]

I had the same problem in my subi, turns out there was a small crack in the
booster so when it was really cold it opened up enough to leak. once it was
warm the crack closed and all was well except the idle would drop slightly
if my foot was on the brake at idle.  My suggestion is to get a vacuum pump
and check the valve cold and warm. then check the booster cold/warm.
regards
Brendan

----- Original Message -----
From: <Quattrospg at aol.com>
To: <quattro at audifans.com>
Sent: Wednesday, January 14, 2004 9:06 PM
Subject: No brake boost when (very) cold - 87 4KQT


> With the recent frigid weather I seem to be experiencing a short period
> without vacuum assistance on the brakes. Pedal stays firm with little
travel. Once
> the car warms up a bit all is well. Only happens in really cold weather
and
> when the car is cold soaked.
>
> Any ideas? My only guess is that the check valve is freezing/sticking, not
> allowing the engine to pull a vacuum on the booster until heat from the
engine
> can free it up.
>
> Thanks in advance
>
> Bill
> 87 4KQT
>
>