Reduced Brake and Paddle goes down even engine stopped.

[VishwaR]

Hi All,

I recent a bought a 4dr5 jeep which was in a garage without running for few years. I hand over a well known 4dr5 mechanic. He told he replaced  all brake washer, nozzles.. He tested the brake he could managed to brake with locking wheels (Assume he is not a giant :D) . I noticed a change in brake while I started to bring the vehicleNow brake is in a very very dangerous situation. I am afraid to take the vehicle into road   . I controlled speed from the gear. And could came very slowly. And it was the very first driving moment of the vehicle. So I do not have a idea about before the repair.

Anyway I do not like to go to above mechanic because he is charging too much (Brake repair 6500/- with brake  nozzles, washer replace, no replacing brake pads) and he is dishonest. Any way I would like to troubleshoot it myself.

Symptoms :

• Brake paddle goes down halfway without much effort after engine shutdown. Remaining half is harder.
• Brake paddle become loosen after engine start. 
• I could hear the air flowing sound while braking. (After engine stopped). -

                                     I assumed vacuum  works properly.

• Brake paddle becomes harder after for each paddling after engine stopped.

                                     I assumed vacuum  works properly.

• Brake oil level keep constant. 

My conclusion :

• Remains air within brake oil ducts. 

Any ideas please? I need to find the root cause. How to check the vacuum system functioning?

Thank you very much.

 

Edited November 12, 2016 by VishwaR
More clariafication

[peugeot407]

There cant be any free movement of the brake paddle when you exhaust the servo. is it drum or disk brake?  if its drum try adjusting brake at the slave and do a proper bleeding. 

[TheClutch]

first , you should have decent mechanical knowledge to own a 4dr5..no offense mate ..but that it is..

second , why you want to brake when the engine is stopped..??

third, the symptoms you have mentioned are not really symptoms ,,it is how the brake works. 

[VishwaR]

1 hour ago, TheClutch said:

first , you should have decent mechanical knowledge to own a 4dr5..no offense mate ..but that it is..

second , why you want to brake when the engine is stopped..??

third, the symptoms you have mentioned are not really symptoms ,,it is how the brake works. 

Hi TheClutch,

Thanks for replying. I have some mechanical back ground but a newbie :).As a exampe, I am doing the whole electrical wiring for above mentioned 4dr5. And now it is in the final stage. 

I mentioned above check list to make someone give me a clear solution. I included all the test cases coming into my mind . 

 

My major concern is 

• Brake paddle goes down halfway without much effort after engine shutdown. Remaining half is harder. And going down to the bottom.. Is it acceptable ?

Thank You

 

 

 

 

 

Edited November 12, 2016 by VishwaR
spelling istake

[VishwaR]

8 hours ago, peugeot407 said:

There cant be any free movement of the brake paddle when you exhaust the servo. is it drum or disk brake?  if its drum try adjusting brake at the slave and do a proper bleeding. 

Hi peugeot407,

It is Drum. I will have try. Thank you for your reply

Is that extra free brake paddle movement coming from air bubles or slave side free space ? or both?

Thank you.

[andunslg]

Hi,

As far as I know, the break system is a closed system. There is liquid inside the system. So when the engine is stopped, if there is no air in the system, can the paddle go down?

I guess in this situation there may be air in the break lines. If not there may be loose parts in the system which cant bear the pressure. Simply break washers.

WDYT?

[Davy]

Perform the test below explained by @Rumesh88 to determine if your brake booster (servo) is working normally. According to your description, it looks like the booster is working as it should, but do this yourself since it's easy and we can rule out a faulty booster by doing so.

Was the old oil in the system drained and was the system bled on all four corners with the new oil? 

Was your master pump overhauled with a repair kit? 

Given that the car was sitting for a long time without being used, new oil is a must and if the pedal sinks, get the master pump overhauled. These are very minor repairs and wouldn't cost you much. 

Edited November 21, 2016 by Davy

[VishwaR]

hi all,

Thank you for all your valuable replies. And pardon me late reply.

Now the problem is in a new stage. And it is terrible. :D.

I replaced all the slave cylinder washers. And master pump as well. Master pump had original Nissan washers. So the internal suface is almost new. Slave cylinder are old. But not having considerable gaps.

But the liners are terrible. Some are worn out closed to metal. Some are almost new. Some liner ends are having welding marks to increase the liner total length.

I bleed system in all corners several time to verify it. Filled new oil. Adjusted the cylinders to minimize gap between liners & drum.

Observation:

almost no brake

paddle goes halfway very softly. And remaining half gets harder step by step.

brake works while rapid paddling. (after third paddling)

Any suggestions?

Steps to be followed to narrow down the problem?

Is there a method to isolate each wheel's brake duct? ( To narrow down the problems)