Loss of brakes

[Shoppinit]

That’s why I asked the questions I did.

[steve2003rs6]

Hi guys. And thank you for all the advice. Have had 2 separate problems.
1) on cold start. Revs all over the place. No brakes. Had to really push the brake pedal hard.
Leaking vacuum seal on throttle body. At least that’s what the garage has told me.
Havnt had that since ?
2) now I had no brakes when braking and foot went straight to the floor with no resistance at all. Pumped the brake a few times and managed to stop.
Used the car all day yesterday and no problems. Although I am leaving plenty of distance between me and the car in front.
Spoke to grizz at unit 20 yesterday. Car booked in.
At the same time we are fitting pss 9 ,S and new top mounts to all 4 corners.
Also have a nasty suspicion that the local garage has installed the wrong control arms recently.
Just want it all sorted so I can really enjoy the car again.
Thank you all once again.

[steve2003rs6]

Just a quick update. Have not had a repeat problem with the brakes since.
It seems short distances are ok.
Problem arises on long runs ????
I presume short distances the brakes are cold and long distance brakes hot.
Short distance I am the only one in the car.
Long distance my wife is usually with me.
Will try banning my wife from getting in the car first ????

[chunky79]

Just a quick update. Have not had a repeat problem with the brakes since.
It seems short distances are ok.
Problem arises on long runs ????
I presume short distances the brakes are cold and long distance brakes hot.
Short distance I am the only one in the car.
Long distance my wife is usually with me.
Will try banning my wife from getting in the car first ????

Just let the wife do the long distance driving on her own, you stick to the short distances.
Wonder if you have a brake dragging and it's boiling the fluid?

[srichards]

It's worth checking all 4 wheels and seeing if there is a hot one.

[Nige_RS4]

Pedal to the floor can also be a result of fluid boiling. The C5 is no lightweight. Had you been driving hard previous to that? Maybe consider a higher temp fluid such as Motul RBF 660.

[steve2003rs6]

Thanks guys for the responses.
I do not let my wife drive my car !
Hardly ever drive it hard.
But do give it a blow out now and again
Thankfully she does not drive and never held a licence.
Fluid boiling. That’s interesting. I don’t know what oil they used when I had the last brake fluid change. At unit 20 soon and have spoken to grizz about this.
Doing pss9,S and top mounts all round.
thanks again for advice.
Will check motul 660 out.

[Shoppinit]

What Chunk said. Binding calliper.

[steve2003rs6]

Quick recap.
1) loss of brakes. Stood on brake pedal really hard very little brake pedal movement.
Always on Cold start revs all over.
Eventually the garage found a vac leak on throttle bodies. New seals fitted. Not had that since.
2) most recent. Out for a leisure drive had to brake. No resistance foot all the way to the floor and nothing.
When cold all seems ok.
Seems to happen when brakes are hot. say after a couple of hours of driving.
Just had a reply from a member which is of interest. Regarding boiling brake fluid if a brake is running hot.
Backtracked all my garage invoices last night. Car was perfect until the vac hoses were replaced.
Could be wrong but seems logical to me to investigate.

[GreggPDX]

I don't believe in coincidence that the vac-hoses have recently been touched. Have you tried spraying carb-cleaner or starting fluid around the manifold when the car is idling? If you are having vac-leak issues, you should get a surge in RPM when the fluid gets near the leak. Try go get under the manifold since that's where a bunch of lines run. My guess is failed Suction Jet Valve. A buddy nearby had similar issues and that's what we found. Replacing it is a bitch because you have to remove the manifold and the process involves a lot maneuvering of wires and hoses. Nothing specifically too hard, just time-consuming.

[steve2003rs6]

Many thanks for your advice.
Hope unit 20 will sort it out.
Some very good recommendations in the above messages.
Will list what we find out.
Itching to get the car done so I can really appreciate the drive.

[steve2003rs6]

Think the moral of all this is at whatever the cost. Do extensive research to find a good honest technician familiar with your car.
As I have found many garages return your vehicle worse than it went in.
Expensive Lesson learned.

[steve2003rs6]

Update. Looks like the rear brakes are binding and boiling the brake fluid.
New pads Calipers and discs being fitted.
Will see if this cures the problem.

[chunky79]

Will see if this cures the problem.

[steve2003rs6]

Gregpdx.
Looks like I had 2 problems.
1) Spot on mate. Valve under manifold and a bitch to get at - brake booster valve.
See my other topic “at unit 20”
2) rear brakes binding.

Item 1 will be done in 2 weeks time.
Item 2 done. new discs calipers and pads fitted.