Good morning guys.

 

Yesterday at night while driving (75km/h)

I got into a damn pothole, i got a puncture and i immediately park to change the tire.

 

But after that u felt the car underpowered

 

Then i stop to inspect  and i got that smell of hot brakes.

 

Both front tires are with the brakes stuck, the left one (the side i got the pothole) more than the right side.

 

What could be?

17 minutes ago, Kharl said:

What could be?

Well, my immediate thought is that you've pinched one or both front brake pipes.

Did you check  to see if the brake lines had damaged? Any contact marks on the callipers and / or carriers? Have you buckled the wheel really badly??  

 

 

We removed both wheels, no visible damaged to any brake lines.

 

The deflated tire is not bend or damaged, and the wheel is ok

 

The mechanic says he wants to replace both hoses.

 

What i fund weird, ok, that could be the cause, i had a car years ago that had the same symptoms: brakes stuck after  breaking and some minutes to release but in this case why and how, after a hole? 

I've seen Flexi brake lines that look ok to the naked eye but were knackered when I actually tested them. 

 

Maybe the sudden bang and perhaps momentary stopping of the wheel has caused the ABS to kick in and maybe stick?!

But this car has not ABS.

Would be the same case?

ignore me then

If it's both sides could it be the master cylinder, how were the back brakes, if you open a bleed valve and the wheels turn freely then it might be the master cylinder or booster sticking.

 

How To Find Out If You Have A Bad Brake Hose - 

 

 

Yes, if i open the bleed valve it release the wheel).

 

The rear brakes are working fine

Hitting the hole might be a coincidence or as I remember it your car caries a lot of weight so the shock might shake up and distributed the crud in the braking system more.  Or it might be some other sort of damage to the front so once the wheels are off a close inspection of all in those areas but with both front brakes staying on and hitting a pothole only one side, subject to what might be found on inspection, the brakes are the place to start.

 

A very thorough flushing of the whole system might be in order, the colour and state of the current fluid might show what is required and what has been happening.

 

With brakes (and suspension, which both include tyres) it is best to replace both sides to keep things even, or even sets of four if required, so braking, steering and handling remain straight.

 

Edited 26 April, 20224 yr by nta16
spelling

Thanks for the reply, no, i use the car for way long trips, but not for heavy weights

It is your long trips that has you carrying the extra weight, four wheels and tyres on the roof and a David Attenborough living and survival kit in the car, you use your car a bit different to UK owners.  🙂

 

Let us know what it turns out to be and if the pothole caused any other damage, good luck.

 

23 hours ago, Kharl said:

But this car has not ABS.

Would be the same case?

Opening the bleed nipple releases the pressure then I would be looking at the brake servo and the master cylinder pushrod & linkage if applicable to ensure that it has free play, & that the pedal is returning to the correct height.

 

Were you perhaps already on the brakes when you hit the pothole? Did the impact throw you forward & make you stand on the brakes?

6 hours ago, J.R. said:

Opening the bleed nipple releases the pressure then I would be looking at the brake servo and the master cylinder pushrod & linkage if applicable to ensure that it has free play, & that the pedal is returning to the correct height.

 

Were you perhaps already on the brakes when you hit the pothole? Did the impact throw you forward & make you stand on the brakes?

No brake when the pothole.

Brake hoses replaced, and brake lines air compressor cleaned.

Brakes fells very good but still getting stuck, even without pressing the pedal, just for turning on the engine.

 

We accidentally discovered that the brakes gets free when we loose the bolts  that attach the master cylinder  to the vacuum  booster. 

On 26/04/2022 at 16:58, J.R. said:

Opening the bleed nipple releases the pressure then I would be looking at the brake servo and the master cylinder pushrod & linkage if applicable to ensure that it has free play, & that the pedal is returning to the correct height.

 

 

The weird thing is that it has fre play and the pedal is returning,  but a ittle bit harder.

 

I already quotate abrake servo.

To confirm the diagnosis clamp off the vacuum hose to the servo before starting the engine, the pedal force needed to brake will be much much higher (I dont recommend that you drive like this) but the brakes should not lock on.

On 25/04/2022 at 20:32, nta16 said:

if you open a bleed valve and the wheels turn freely then it might be the master cylinder or booster sticking.

To check booster - with engine off step on brake pedal - pedal hard, take foot off pedal, start the engine and step on the brake pedal if pedal sinks it's the booster.

ETA: Wrong, doh, thinking of fluid leak.

Edited 29 April, 20224 yr by nta16
ETA:

2 hours ago, nta16 said:

To check booster - with engine off step on brake pedal - pedal hard, take foot off pedal, start the engine and step on the brake pedal if pedal sinks it's the booster.

 

 

The pedal should sink slightly when the engine is started after the pedal has been pumped up hard. That's normal servo operation. Servo failure gives a rock hard pedal.

 

The only time I've ever seen a servo fail is due to lack of vacuum supply, .i.e. split hose, dodgy non-return valve or failed vacuum pump on diesels. They just don't go wrong, and certainly not from going into a pothole.

Edited 28 April, 20224 yr by TMB

I have seen ( only once) and it's easily identified by clouds of white smoke from the exhaust. It was failure of one of the seals in the master cylinder and fluid was seeping into the servo and hence into engine and being burnt.

It wasn't strictly a servo fail but more of a very brown pants moment.

19 hours ago, TMB said:

The pedal should sink slightly when the engine is started after the pedal has been pumped up hard. That's normal servo operation. Servo failure gives a rock hard pedal.

Yeah my bad I was thinking of fluid leak (and pedal sinking to floor rather than as normal) that does go through the engine and out of the exhaust as white smoke.

 

Whatever the cause Kharl has found a couple of things wrong with his brakes.  Personally I'd still want a good flush after putting compressed air through the lines as I've known lots of **** come off seals and elsewhere and be in the system more than just the lines, including the insides of reservoirs coated.

 

Edited 29 April, 20224 yr by nta16

On 27/04/2022 at 18:18, Kharl said:

Brake hoses replaced, and brake lines air compressor cleaned.

Brakes fells very good but still getting stuck, even without pressing the pedal, just for turning on the engine.

We accidentally discovered that the brakes gets free when we loose the bolts  that attach the master cylinder  to the vacuum  booster. 

 So basically if you jack a wheel up:-

1/ Before engine running ensure wheel rotates freely. You may need to pump the pedal a few times to try and evacuate any vacuum that may be present from running engine.

2/ If when engine is started wheel does not rotate as you say - if this is the case have someone starting to rotate the wheel with engine not running and while still rotating start the engine. Does rotation become hard or even stop immediately the engine starts.

3/ If rotation does stop with engine running, keep the engine running and slacken the master cylinder to servo brakes - if this frees the wheel, either if studs and nuts cut some washers to form a 'C' shape to allow sliding over the studs between the master cylinder and servo, or if bolts fit washers between master cylinder and servo using washers of a suitable thickness to ensure brake still rotates freely when tightened back up.

4/ If washers leave wheel to rotate freely leave in place and test drive "EXTREMELLY CAREFULLY" to try brake operation.

5/ Which you may want to try before 3/, pull vacuum pipe from servo, not forgetting that there could be a non-return valve at the servo connection and see if rotation is free with engine running.

 These checks should identify if a servo issue or master cylinder issue rather than collapsed hoses or dirt in system and will allow people to comment with new suggestions.

 ADDITIONAL - You may want to try these checks on each wheel - jack NS and OS front and rear separately to ensure not an individual circuit issue.

Edited 29 April, 20224 yr by KeithCheetham
Additional check on each corner

On 27/04/2022 at 19:53, Kharl said:

The weird thing is that it has fre play and the pedal is returning,  but a ittle bit harder.

 

Can you clarify the statement "but a little bit harder".