Skoda Octavia Mk 1 braking in the rain on motorways - odd pedal hardness

[Zak33]

Lo people

I'm at a loss on this - utterly.

My Mk 1 Octavia brakes superbly. It's in daily use and they're good anchors. News front discs (Brembo) and pads (Pagid) in summer and healthy rears.

In cross country driving, any weather - consistent
On motorway or dual carriageway in thre dry - consistent

But drive on motorways and dual carriageways in rain/wet slush etc.. with no regular braking.. and when you do brake the pedal is rock hard and the brakes need 3 times the force
Lift off, and reapply.. power back immediately

It takes many miles of constant wet high speed driving to act like this.

and never in the dry

Anyone got any idea?

[kalniel]

Water getting into the brake hydraulics from spray at high speed?

[Zak33]

Possibly yes but from where? It's really quite dry under that bonnet.. I checked again today. Any idea where to look?

A hard pedal normally denotes a lack of vacuum assistance. I'd be looking for a split rubber hose. But thge brakes are good as gold except under these wet motorway conditions.

[kalniel]

Sorry I missed that it sorts itself out after a single press. Calliper seizing?

[Zak33]

Sorry I missed that it sorts itself out after a single press. Calliper seizing?

that's possible... not condidered that. yes...

Doesn't pull sideways, but then as it's so hard I just lift off and go again and all is well.... it's a viable option.

[DanceswithUnix]

Sounds like you are losing vacuum, and hence power brake assist.

[Zak33]

Sounds like you are losing vacuum, and hence power brake assist.

yup..it does feel like that
and that's why I'm confused that its only in the rain and on long stretches where I don't touch the brakes

[DanceswithUnix]

yup..it does feel like that
and that's why I'm confused that its only in the rain and on long stretches where I don't touch the brakes

Is it a diesel?? They use a vacuum pump, driven I think usually by the cam. Perhaps it doesn't like sustained motorway revs.

Either that or there is a leak which is reset when you pump the pedal, and you naturally stay off the pedal in the rain?


Edit: My best guess is the master cylinder starting to play up. The rain bit is odd though, I expect seals to play up more at high temperatures not low.

[Ttaskmaster]

Whereabouts in the world are you based, Zak?
I have a very good local mechanic who is very familiar with the old MkI Octy... especially blue ones!

You might also want to ask about this on the Briskoda forum....

[Zak33]

Is it a diesel?? They use a vacuum pump, driven I think usually by the cam. Perhaps it doesn't like sustained motorway revs.

now that's interesting.... didn't know that. ta

learning as i go on this one as it's only in the rain. Similar driving to in thge dry to be fair.. not less or more aggresive in dry or wet.