TD5 Brake pedal creep?

Galen · Jun 6, 2008

Hello everyone,

I have a brake pedal that likes to creep...

Stamp on the pedal a few times to make it hard (fnarr) and then keep pressure on the pedal and it seems fine. Doesn't appear to creep at all.

Star the engine and perform the same test and the pedal creeps all the way to the floor in around 7 seconds.

There are no obvious leaks anywhere and the brake fluid doesn't appear to be discoloured.

Is this caused by aged fluid or is there a more sinister reason behind it?

Galen

slob · Jun 6, 2008

check yer master cylinder
get someone to pump the pedal while you look inside the reservoir, if yer see bubbles come up its fooked

Galen · Jun 6, 2008

Would bubbles mean the fluid is fooked or the master cylinder is fooked?

I'm off to check for bubbles....

Galen

Edit: No bubbles observed.

slob · Jun 6, 2008

did you try watching while the pedal went to the floor?

if you see bubbles yer cylinder is goosed.

if you have no fluid leaks and yer pedal is going all the way down then either yer low on fluid or yer cylinder is goosed

Galen · Jun 6, 2008

slob said:
did you try watching while the pedal went to the floor?

Allegedly, but wifey was operating the pedal and they never lie...
I'll stamp on it myself tomorrow and let her take a look see.

slob said:
if you see bubbles yer cylinder is goosed.

if you have no fluid leaks and yer pedal is going all the way down then either yer low on fluid or yer cylinder is goosed

No obvious leaks. The fluid level is pretty much up to the max mark and hasn't been topped up for a while.
Time to price up the brake cylinder I suppose, or a repair kit if they're available.

Thanks for your info slob.

Galen

landy10 · Jun 6, 2008

So let me get this right, when engine is off you can pump the pedal and it goes hard, start the engine so the vacumn kicks in and the pedal will initially pump to be hard then eventually it creeps down to the floor almost?
Im not questionin sir slobs theory but, most cars ive driven tend to do this when started, by all means be sure to check everythin regardin the brake system coz you dont mess where brakes are concerned, but also check against other vehicle of same type to see if it does the same.
Like i said not callin anyone into question but just to double check before jumpin in and spendin hard earned.

Galen · Jun 7, 2008

landy10 said:
So let me get this right, when engine is off you can pump the pedal and it goes hard, start the engine so the vacumn kicks in and the pedal will initially pump to be hard then eventually it creeps down to the floor almost?

That's pretty much it. It takes around 7 seconds to drop to the floor.
Once it's done that if you pump it twice it's rock solid again for another 7 seconds.

landy10 said:
Im not questionin sir slobs theory but, most cars ive driven tend to do this when started, by all means be sure to check everythin regardin the brake system coz you dont mess where brakes are concerned, but also check against other vehicle of same type to see if it does the same.

I'd expect the vacuum assist to drag the pedal down upon starting the engine, but i'd also expect it to stop at some point and hold; not drop to the floor.

landy10 said:
Like i said not callin anyone into question but just to double check before jumpin in and spendin hard earned.

I'll take all and any advice because I have no idea what the problem is. Hence asking the knowledgeable folks here

Galen

Springbok · Jun 7, 2008

Have you not considered the brake booster, especially since it only goes to the floor after you start the engine,

Ray

Galen · Jun 7, 2008

Springbok said:
Have you not considered the brake booster, especially since it only goes to the floor after you start the engine,

If the booster was leaking i'd expect the vacuum assist to fade and resistance to return?

I've never had a unit fail so i've no idea what the result would be.

Galen

Springbok · Jun 7, 2008

Hi,

If it is your master cylinder , dont do wwot I did on my clutch master replaced the rubbers twice and then bought after market new and all was well. good luck.

Ray

Galen · Jun 7, 2008

At the moment i'm leaning toward replacing the fluid and seeing if that makes things better or worse. It's a cheap option and no big deal if it doesn't make any difference.

If new fluid doesn't make a difference it'll probably be a replacement cylinder and/or vacuum servo I guess.

Galen

Galen · Jun 10, 2008

Update:

Flushed the brake fluid today the brakes are more positive, but still have the same 'feature' albeit a little slower.

I did come across this though Brake Parts for Cars

I also spotted that the bloody r380 filler plug is weeping. That's tomorrows job I suppose.

BTW what's with the plastic filler plugs in the axles?

Galen

slob · Jun 10, 2008

if he hadn't sed it wint all the way to the floor ah would have sed "they all do that"
as fer doosul brake creep thats a new un on me, and i have me doubts about how accyreet it is.
but then ave only every own one doosul though i have driven a few and worked on a shed load of em and ave nevva heard of it.

someone should do a poll to see how many have heard of doosul creep

slob · Jun 10, 2008

so ave read this doosul creep thing again and according to that it only happens when yer int moving. so if int dunt do it when yer moving, then thats looks like yer problem. if it does yer back to yer master cylinder

Galen · Jun 10, 2008

slob said:
so ave read this doosul creep thing again and according to that it only happens when yer int moving. so if int dunt do it when yer moving, then thats looks like yer problem. if it does yer back to yer master cylinder

I can't say i've noticed it happening when i'm moving, but will keep an eye on it.

Hellastony · Apr 28, 2021

Galen said:
Update:

Flushed the brake fluid today the brakes are more positive, but still have the same 'feature' albeit a little slower.

I did come across this though Brake Parts for Cars

I also spotted that the bloody r380 filler plug is weeping. That's tomorrows job I suppose.

BTW what's with the plastic filler plugs in the axles?

Galen

Hi Galen,

You can replace the plastic axle filler plugs with these https://www.jgs4x4.co.uk/discovery-2-heavy-duty-brass-differential-filler-plugs/
Much better....

TD5 Brake pedal creep?

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