Intermittant "Hard" & Unresponsive Brakes! - Help Pls, almost wrapped it up

[Fraz-ktf]

Hi.

I've got a brake issue, that's only intermittent and I just can't imagine or fathom what's going on.

Occasionally, my excellent brakes give me a very hard brake pedal and no matter how hard you press it down, the brakes are almost ineffective. (Almost like the pre-servo Morris Minor etc).

Today it happened at highish speed, in the wet though I had time to release the pedal and re-apply, it had no effect, still hard & virtually no brakes. 
30 yards down the road, after checking my seat for stains, the brakes were back to their well behaved, very efficient selves.

What can this be?

Don't know if it's related but my clutch pedal is very slack, with no resistance for the first 1/3 of it's travel and thereafter it is very hard to push, with a biting point quite low, though not intolerably low.

Any suggestions on either the brakes or the clutch or if they are related would be grateful.

Thanks

[Mirez]

They share the same fluid so my first thoughts would be to check the level (there should be a dash-warning generated if low but check anyway), secondly I would suggest bleeding the entire system including the clutch to remove any air. Brake fluid should be renewed every two years so if its not been changed, do that at the same time.

[Fraz-ktf]

That would make sense Mirez, Thanks.  I'll get on to it.

Where is the clutch bleed nipple situated?

[Mirez]

On top of the gearbox, towards the front. Be aware its easy to get air back into the clutch as its done which makes the pedal stay down (requiring a vac) so take it slow and steady!

[Chrispb]

Feel there may be more than just a fluid issue here, intermittent hard brake pedal suggests loss of servo assistance which is usually a split in the connectors of the large vacuum pipe either at the servo or the tandem pump.

[Fraz-ktf]

Checked the brake fluid level - all ok

Flushed / renewed the brake / clutch fluid but still 1/3 travel on the clutch before the hard to depress clutch starts to resist any.

brakes feel a tad more "Keen" but still had the "No servo feeling" once yesterday!

What else should I check?  Some one suggested the Vac Pump?  What's that then? :-)

[insanitybeard]

On the TDI, the vacuum pump is a camshaft driven unit which sits on the passenger side end of the cylinder head, just to the left of the fuel filter as you look into the engine bay. There is a rigid fairly large bore (10-15mm) black nylon (I think) pipe which runs from this unit to the servo (the large drum shaped unit which sits behind the brake fluid reservoir at the rear of the engine bay on the driver's side). It's not easy to check the pipe due to access, but check this pipe carefully- if it splits (most likely at the ends near the terminations) you will lose vacuum supply to the servo and therefore braking assistance. The pipe also incorporates a one way valve which could also cause trouble if it starts to play up.

[marinabrid]

my servo pipe got a split in it after 16 years just before i sold it, cost Ã,£85 for the 2 pieces from the ford dealer ,  i had similar problem , brakes went rock hard the after a few seconds of the engine running and recharging the pipe   they worked for a short while,  then went rock hard again,   quiet unnerving till you know what it is. i also checked seat for stains