Brake problem with audi a4 03 1.9tdi HELP!

[irishwill2008]

Hey i am from ireland,
I failed the NCT (Basically a test to make sure cars road worthy) And failed on my brake system.
Says the following:
Service Brake Operation (5) Pressure no dip = Unacceptable - Fail/refusal.

Master Cylinder/Servo etc (53) Servo = Defective/Sticking.
The guy told me seems to be a pipe off or servo is gone? I went mechanics and the guy drove off tested the brakes he said they are perfect. He opened bonnet and checked and he said they seem grand.
Now for me as a driver, the car stops (brakes perfectly!) The brakes never failed me nor have i noticed anything differently? Basically the guy in NCT said if you pump the brake pedal it goes hard and then looses its suction type of thing?
Is this meant to happen? Any idea what it is. My mechanic cant find the issue as the brakes are perfect? (Might sound dumb here but i push the pedal slightly and bayum the car is stopping.. if i jam on the brakes if im going slow the car comes straight to a halt! Not sluggish no nothing? Perfect brakes in my opinion :L I recently changed the Brake light switch myself like a month ago before i got the NCT as it had the esp and abs light on dash and the code said i need a new brake light switch which i bought and fitted and worked! no more light xD Would i of broken something when fitting this or any ideas?
Any help is appreciated!
Cheers:)

[old guy]

Service Brake Operation (5) Pressure no dip = Unacceptable - Fail/refusal.

In order to pass the Service Brake Operation (5) requirement the technician performs the following test:

First he will pump the brake pedal several times with the engine off to release any residual vacuum stored in the brake booster. After the residual vacuum has been removed the brake pedal will feel extremely hard. He will then start the engine while maintaining pressure on the brake pedal and once the vacuum reaches the brake booster the pedal will "soften" and the pedal will drop noticeably as the brake booster does its job and adds to the overall hydraulic brake pressure.

The second test is performed after the engine is running. At this time the technician will rapidly pump the brake pedal several times and observe the pedal "feel". If everything is working properly the pedal feel will remain consistently "soft" as the brake booster adds to the hydraulic pressure. If you have a small vacuum leak somewhere in the brake booster system the pedal will get "harder" with each rapid depression to the point where it feels like it did with the engine off with no vacuum boost.

Your brakes can feel perfectly normal and still fail the Service Brake Operation (5). I suspect your problem is with the second test. Especially since you don't typically press the pedal repeatedly when stopping. You may have a small vacuum leak that hampers the brake booster recovery.

Try duplicating the tests as I have outlined and report back. If you can get your pedal to go "hard" with repeated applications you have a small leak that needs to be addressed. The test is designed to find potential braking issues before they become a significant impediment to your braking ability.

[irishwill2008]

Thanks very much! Will test this tomorrow morning. Appreciate the help! Will report back the results tomorrow:)

[old guy]

Thanks very much! Will test this tomorrow morning. Appreciate the help! Will report back the results tomorrow:)

And Happy New Year to you!!

I still have 4½ hours to go!

[irishwill2008]

Service Brake Operation (5) Pressure no dip = Unacceptable - Fail/refusal.

In order to pass the Service Brake Operation (5) requirement the technician performs the following test:

First he will pump the brake pedal several times with the engine off to release any residual vacuum stored in the brake booster. After the residual vacuum has been removed the brake pedal will feel extremely hard. He will then start the engine while maintaining pressure on the brake pedal and once the vacuum reaches the brake booster the pedal will "soften" and the pedal will drop noticeably as the brake booster does its job and adds to the overall hydraulic brake pressure.

The second test is performed after the engine is running. At this time the technician will rapidly pump the brake pedal several times and observe the pedal "feel". If everything is working properly the pedal feel will remain consistently "soft" as the brake booster adds to the hydraulic pressure. If you have a small vacuum leak somewhere in the brake booster system the pedal will get "harder" with each rapid depression to the point where it feels like it did with the engine off with no vacuum boost.

Your brakes can feel perfectly normal and still fail the Service Brake Operation (5). I suspect your problem is with the second test. Especially since you don't typically press the pedal repeatedly when stopping. You may have a small vacuum leak that hampers the brake booster recovery.

Try duplicating the tests as I have outlined and report back. If you can get your pedal to go "hard" with repeated applications you have a small leak that needs to be addressed. The test is designed to find potential braking issues before they become a significant impediment to your braking ability.

P.s: If it is the fact there is a leak, will i have to buy a new vacuum pump and if i do (Or even second hand from scrap yard) Will this fix the problem or is there a hose going to the vacuum pump thats leaking and it might not be the pump itself?

[irishwill2008]

Happy new year 2! Appreciate the help, its 12:40 now for us. Hope you have a great new year!

[old guy]

P.s: If it is the fact there is a leak, will i have to buy a new vacuum pump and if i do (Or even second hand from scrap yard) Will this fix the problem or is there a hose going to the vacuum pump thats leaking and it might not be the pump itself?

If you have an automatic transmission you will have a vacuum assist pump. If you have a manual transmission you won't have the vacuum assist pump.

The vacuum leak doesn't have to be related to the pump. It can be anywhere in the vacuum boost system. It can even be the check valve in the brake booster itself. First see if you can duplicate the problem. If you can duplicate it, work with your mechanic and have him listen for a vacuum leak hiss underneath the hood while you repeatedly depress the brake pedal. Also have him wiggle all the hose involved with the brake booster system to see if he can locate a small leak somewhere.

If you can't duplicate the first or second part of the test have the NCT technician show you why he failed your Service Brake Operation test.

Good luck!

[irishwill2008]

If you have an automatic transmission you will have a vacuum assist pump. If you have a manual transmission you won't have the vacuum assist pump.

The vacuum leak doesn't have to be related to the pump. It can be anywhere in the vacuum boost system. It can even be the check valve in the brake booster itself. First see if you can duplicate the problem. If you can duplicate it, work with your mechanic and have him listen for a vacuum leak hiss underneath the hood while you repeatedly depress the brake pedal. Also have him wiggle all the hose involved with the brake booster system to see if he can locate a small leak somewhere.

If you can't duplicate the first or second part of the test have the NCT technician show you why he failed your Service Brake Operation test.

Good luck!

Its manual, thank you very much! Really appreciate it help. Have a great new years! I will try locate this issue tomorrow as NCT is due again sat. If i cannot fix i will ask the technician to show me as you said. Again, thank you very much! I will post back my results tomorrow anyway.
Regards,
Will.

[irishwill2008]

Service Brake Operation (5) Pressure no dip = Unacceptable - Fail/refusal.

In order to pass the Service Brake Operation (5) requirement the technician performs the following test:

First he will pump the brake pedal several times with the engine off to release any residual vacuum stored in the brake booster. After the residual vacuum has been removed the brake pedal will feel extremely hard. He will then start the engine while maintaining pressure on the brake pedal and once the vacuum reaches the brake booster the pedal will "soften" and the pedal will drop noticeably as the brake booster does its job and adds to the overall hydraulic brake pressure.

The second test is performed after the engine is running. At this time the technician will rapidly pump the brake pedal several times and observe the pedal "feel". If everything is working properly the pedal feel will remain consistently "soft" as the brake booster adds to the hydraulic pressure. If you have a small vacuum leak somewhere in the brake booster system the pedal will get "harder" with each rapid depression to the point where it feels like it did with the engine off with no vacuum boost.

Your brakes can feel perfectly normal and still fail the Service Brake Operation (5). I suspect your problem is with the second test. Especially since you don't typically press the pedal repeatedly when stopping. You may have a small vacuum leak that hampers the brake booster recovery.

Try duplicating the tests as I have outlined and report back. If you can get your pedal to go "hard" with repeated applications you have a small leak that needs to be addressed. The test is designed to find potential braking issues before they become a significant impediment to your braking ability.

I did the test, it past the first test as when i pumped 7 times when engine off it got really hard and stayed that way.. When i started her up with pushing on pedal(It being hard still) when engine started it got really soft fast and i could feel it when i started. When it was soft and engine running i pumped 7 times again like said and every pump it had a bit of preasure like it was getting hard but it was going soft after words? but kinda staying hardish not as hard as it was when i did it with engine off. Does this indicate a hole in the system or? Let me know! Thanks a million, hope you had a great new years night!

Edit: P.s, Its not statying as hard as it was when i did it with engine off. Theres pressure as if its trying get hard but doesnt stay AS hard. just stays with bit of pressure.

[old guy]

When I pump my brake pedal repeatedly at idle the pedal stays "soft". It sounds like your braking vacuum system is functioning properly but you may have a small vacuum leak somewhere that is causing a slight delay before the brake booster reaches full vacuum between pumps.

As I mentioned before try jiggling the hoses starting at the connection to the brake booster and working outward toward the vacuum source to see if you can find anything. Pay particular attention to the connection where the vacuum hose goes into the plenum chamber.

[irishwill2008]

When I pump my brake pedal repeatedly at idle the pedal stays "soft". It sounds like your braking vacuum system is functioning properly but you may have a small vacuum leak somewhere that is causing a slight delay before the brake booster reaches full vacuum between pumps.

As I mentioned before try jiggling the hoses starting at the connection to the brake booster and working outward toward the vacuum source to see if you can find anything. Pay particular attention to the connection where the vacuum hose goes into the plenum chamber.

When i started the car i couldnt hear any noises but when i turn the engine off i hear a mad hissing noise by where you put brake fluid in? It seems to be coming from what i did research with called a check valve? I think its at the master cylinder its the thing in the back that the check valve goes into by where i put the fluid in?
Do you reckon its the check valve or the master cylinder? Or perhaps its something else? Thanks very much! Without yourself i wouldnt of found this! My mechanic is away so myself and the misses was out haha. Cheers!

Edit: It sounds like air is coming out? As if its air coming from burst tyre something like that? Hard to describe but its in that location.

[old guy]

You should not be hearing a hissing noise. I just took a few quick pictures of where to check for leaks. The first is the connection through the plenum chamber wall.



You will have to remove the plenum cover to check the second connection.



Good luck!

[irishwill2008]

You should not be hearing a hissing noise. I just took a few quick pictures of where to check for leaks. The first is the connection through the plenum chamber wall.



You will have to remove the plenum cover to check the second connection.



Good luck!

I pumped the pedal with engine on, i couldnt hear over the engine so when i turned the car off i heard like a hissing noise like loosing air type of thing around the back towards windscreen above the brake fluid place. Tomorrow morning i will get up take pictures of where i can hear it but its hard to determine as it seemed to be coming around the area you showed above so maybe thats where it is? I will take the cover off and re try as it was dark and not the best of nights to check. Thanks a million!

Update:

Image of where i hear the noise around. Dont mind the marks as this is from google the image.

[old guy]

If you can hear it you should be able to locate it pretty quick once you remove the rain tray.

Good luck!

[irishwill2008]

I pumped the pedal with engine on, i couldnt hear over the engine so when i turned the car off i heard like a hissing noise like loosing air type of thing around the back towards windscreen above the brake fluid place. Tomorrow morning i will get up take pictures of where i can hear it but its hard to determine as it seemed to be coming around the area you showed above so maybe thats where it is? I will take the cover off and re try as it was dark and not the best of nights to check. Thanks a million!

Update:

Image of where i hear the noise around. Dont mind the marks as this is from google the image.

Its around the yellow arrow is where i hear the noise but its is around that area?
It sounds like its coming from that drum above the yellow arrow? Is that the master cylinder or?

[old guy]

That large round black object is the brake booster. If the hissing is coming from inside the booster you probably have a damaged diaphragm in the booster unit itself which will require replacing the booster. Have you mechanic listen to the hiss and get his opinion. It's kinda hard to troubleshoot from across the pond on something that requires an "ears on" application..

Again, Good luck!

[irishwill2008]

That large round black object is the brake booster. If the hissing is coming from inside the booster you probably have a damaged diaphragm in the booster unit itself which will require replacing the booster. Have you mechanic listen to the hiss and get his opinion. It's kinda hard to troubleshoot from across the pond on something that requires an "ears on" application..

Again, Good luck!

Thanks very much! It was one of the cables you said had a really hair line tear like proper small you cant visually see it? But my mechanic took the ones off you said we blew into it and you can hear like a weird funny noise which you can pretty tell its broken? So got new hose and it passed! Passed literally 20 minutes ago! Thank you so much for your kind support/help with this issue! Im pretty sure if it wasnt for the assistance we wouldnt of found the issue.
With that said, My second gear grinds when i put it into gear at high speeds. My mechanic said its the synchromesh something like that thats gone? I put gear treatment and a whole new gear oil into the car few months ago but still grinds in second gear. Is there a way to temp fix the issue or do something that can help or do i need to get that gear fixed? I was investing in new gearbox but i think its way to dear for 1 gear? Any ideas? Cheers!

[old guy]

Glad to hear that you got your brake sorted out and passed the inspection!

Unfortunately there really isn't any cure for a worn synchronizer other than replacement. You may be able to minimize it a little with a different gear oil. What was the gear treatment and gear oil that you used? Did it make any difference with the grinding?

[irishwill2008]

Glad to hear that you got your brake sorted out and passed the inspection!

Unfortunately there really isn't any cure for a worn synchronizer other than replacement. You may be able to minimize it a little with a different gear oil. What was the gear treatment and gear oil that you used? Did it make any difference with the grinding?

In all fairness, i cant remember off the top of my head but i told the guy in the car shop what the gear is doing and he said such and such would be good and when i showed the mechanic he also said it would help? Expensive also including the treatment. After it was done, i gave her a drive and into second and she crunched. When i first bought the car in july when i tested it, wasnt crunching but the day i paid the cash and drove her home it started crunching so i thought she must of done it up so itl be smooth for a day or 2. If i clutch and move the gear stick at 2nd but not engage for 5 seconds and then push her in it doesnt crunch its messy but thats how i drive her now so no one outside hears me grinding/crunching second. It is annoying pulling out of bad bends in 1st then i lash her into second to get the power and then it crunches.

[old guy]

There are two things that can cause the gears to crunch. Worn synchronizers or a problem with the clutch engagement. Where does your clutch engage? Does it engage close to the floor, near the middle or closer to the top?

[irishwill2008]

There are two things that can cause the gears to crunch. Worn synchronizers or a problem with the clutch engagement. Where does your clutch engage? Does it engage close to the floor, near the middle or closer to the top?

Well it only crunches on second gear, all other gears are perfect! How do i know where it engages? Pretty noob question apologies.

[old guy]

Well it only crunches on second gear, all other gears are perfect! How do i know where it engages? Pretty noob question apologies.

When you start to lift you foot up on the clutch pedal to engage the transmission where does it start to move the car? Does it start to move the car as soon as the pedal starts upward or does it engage with the pedal halfway up the travel or does it engage close to the top of the travel?

If the clutch starts to engage close to the floor that can be a symptom of air in hydraulics and can also cause the gears to grind when shifting. If the engagement is in the middle or toward the top of the travel the problem is probably a worn synchronizer.

[irishwill2008]

When you start to lift you foot up on the clutch pedal to engage the transmission where does it start to move the car? Does it start to move the car as soon as the pedal starts upward or does it engage with the pedal halfway up the travel or does it engage close to the top of the travel?

If the clutch starts to engage close to the floor that can be a symptom of air in hydraulics and can also cause the gears to grind when shifting. If the engagement is in the middle or toward the top of the travel the problem is probably a worn synchronizer.

When i press the clutch to the floor, as i move it as if im letting go of the pedal near the near/top center it starts to pull. So When i floor it it doesnt move but as im releasing the pressure as it comes to the end of the travel it moves. My mechanic said i got a pretty new clutch in the car but doing this i dunno if its bad or good? Thanks!

[old guy]

When i press the clutch to the floor, as i move it as if im letting go of the pedal near the near/top center it starts to pull. So When i floor it it doesnt move but as im releasing the pressure as it comes to the end of the travel it moves. My mechanic said i got a pretty new clutch in the car but doing this i dunno if its bad or good? Thanks!

I agree with your mechanic. That sounds like normal operation for and Audi clutch. It sounds like you are going to have to replace your 2nd gear synchronizer to stop the crunch.

Sorry!

[irishwill2008]

I agree with your mechanic. That sounds like normal operation for and Audi clutch. It sounds like you are going to have to replace your 2nd gear synchronizer to stop the crunch.

Sorry!

Ah no worries! But hey, at least i got a decent clutch i dont have to worry about haha. I really appreciate all the help! I guess i goto replace this synchro.
Again, i really appreciate all the help you gave me on passing my NCT! My mechanic didnt know what was wrong with it and if it wasnt for you itl be like finding a needle in haystack even though it was looking for that crack ;) But i really appreciate the help!
Thank you very much.
Hope you have a great year!
Cheers pal.