406 Brake Servo problem

Hi
hope someone here may be able to advise. I have a 406 1.9TD. When the engine
is initially started the brake servo does not function as it used to till
the engine has run for a few minutes, it scared the hell out of me yesterday
when I got to the end of my road approaching the main road and pressed the
pedal to get that horrible solid feel and no real braking action. After
running for a while it seems OK BUT if the brakes are used several times in
succession the assistance appears to disipate. I've checked the valve in the
servo vacuum pipe and that is OK ( only passes air in the correct
direction ) put finger over end of vacuum pipe and there is suction there
I don't have a vacuum gauge to measure the suction) I need to resolve this
problem as I'm off to the mountains soon and would hate to run out of brakes
on some of those hairpins!

It MAY be relevant but the engine was recently changed by a garage and since
then the engine is prone to misfire when stone cold.

Thanks

Ron

 

Ron
The vacuum is provided by a pump on the end of the cam shaft. Check the air
hoses from this are connected and not leaking they are also used to provide
the slow fast tickover control and operate the turbo. One of the pipes on
this circuit has a T connector with one way blanked off check the blanking
plug is in place still. You sound as though you are loosing vacuum so are
you using the original vacuum pump as a result of the engine change. I would
be pointing the figure at a fault as a result of the garage not doing their
work thoroughly.
Mike

 

Ron,

Did you ever get to the bottom of this problem, I am experiencing EXACTLY
the same troubles and would appreciate some info if you ever found out the
exact reasons.

Tubes SEEM to be ok, as does the vacuum pump (although I don't have a
vacuum gauge).

Intertesting you had a new engine fitted as I've just recently had my head
gasket done - was the problem related (or cooincidence that you too had
major engine work done)?

Help would be very much appreciated

Jim