PDA

View Full Version : This doesnt seem completely normal



AudiNFS
08-22-2010, 11:08 AM
I have a '98 A4 1.8T Quattro. I've noticed that when I'm driving at night and put it into neutral, if I put the brakes on the needle on my RPM gauge moves constantly from about 900RPMM's all the way down to about 400 or 500. Then as soon as I come to a stop and let off the brakes, the RPM's sit at a normal (for me anyway) 800 or 900. Is this a serious problem that should be addressed?

Accord4tehloss!
08-22-2010, 11:30 AM
Sounds like you could have a large vacuum leak. Putting on the brakes uses vacuum which makes it worse.

AudiNFS
08-22-2010, 11:33 AM
well, this only happens at night because of cooler temps outside i think. during the day it never happens. Does that make a difference?

geeky
08-22-2010, 11:39 AM
The cooler temperature in the evenings can contract rubber hoses from vacuum lines and make the crack bigger so that the vacuum leak becomes more evident at night/cold temperatures.

AudiNFS
08-22-2010, 11:46 AM
i see. i did have brake work done before i got the car... this only happens when i use the brakes and ive had my car for 2 months and havent really had any big or noticeable issues from it

AudiNFS
08-22-2010, 11:54 AM
so really i just need new vacuum lines?

nick71692
08-22-2010, 12:28 PM
sounds that way

AudiNFS
08-22-2010, 12:36 PM
sounds that way

is there such things as upgraded vacuum lines so this doesn't happen again? if there is, how much are they and how much would a shop charge to install them?

thenj3
08-22-2010, 12:38 PM
the vacuum line going to the booster could be loose. i would check that before buying all new lines

AudiNFS
08-22-2010, 12:43 PM
the vacuum line going to the booster could be loose. i would check that before buying all new lines

the booster is where? and also I did put in a boost gauge and connected it to the FPR. Could that have anything to do with the RPM's being wierd?

Also i still get full boost..

walky_talky20
08-22-2010, 01:21 PM
I would check for cracks in the large "L" shaped hose on the right side of the intake manifold. It leads to the plastic "suction jet pump" and onward to the brake booster. This line usually cracks on the inside of the 90 degree bend. Also, check the PCV system. Most of the venerable parts exist under the intake manifold, but can be inspected pretty well through the runners with a flash light. In particular, the plastic pipe that comes out of the oil filter housing likes to crack.

Definitely sounds like a vacuum leak. On older 1.8T's it is common to have vacuum and boost leak problems as all the lines begin to deteriorate, especially the ones that deal with the oily blow-by gases.

AudiNFS
08-22-2010, 01:26 PM
I would check for cracks in the large "L" shaped hose on the right side of the intake manifold. It leads to the plastic "suction jet pump" and onward to the brake booster. This line usually cracks on the inside of the 90 degree bend. Also, check the PCV system. Most of the venerable parts exist under the intake manifold, but can be inspected pretty well through the runners with a flash light. In particular, the plastic pipe that comes out of the oil filter housing likes to crack.

Definitely sounds like a vacuum leak. On older 1.8T's it is common to have vacuum and boost leak problems as all the lines begin to deteriorate, especially the ones that deal with the oily blow-by gases.

Assuming theyre all cracked or leaking, how much would it cost to replace them with labor? And also what is the PCV system? How much would that be to fix?...

I'd really like to just get all my vacuum lines and everything like that replaced/fixed all at once so I don't have to do it again. my car has 157,000 miles on it...

MLFHNTR
08-22-2010, 02:21 PM
the booster is where? and also I did put in a boost gauge and connected it to the FPR. Could that have anything to do with the RPM's being wierd?

Also i still get full boost..

The FPR would/should not contribute to the problem so stop looking there. The brake booster is going to be on your fire wall and there will be a line running o it. that line might have some crackage in it. Mine fell apart on my 1.8T.

thenj3
08-22-2010, 02:25 PM
since your at 157k miles i would try changing all the lines as there most likely all cracked and worn. if you strapped for cash just look to find where the leak is and then go from there.

AudiNFS
08-22-2010, 02:32 PM
since your at 157k miles i would try changing all the lines as there most likely all cracked and worn. if you strapped for cash just look to find where the leak is and then go from there.

I want to just replace all the lines you're right. How much would it be to do that with labor estimate in your opinion at a garage?

AudiNFS
08-22-2010, 04:07 PM
Could someone please bump this incase anyone else has opinions? Thank you

walky_talky20
08-22-2010, 07:55 PM
I think a shop would charge at least 2 hours to do it. There is a lot of small annoying clamps, and they may want to remove the intake manifold to do the job. The parts will be a little bit of money as well. You will want to replace all of the PCV stuff if you're going in that far. You'll probably want this stuff:

http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES5942/
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Search/Vacuum_Hose/ES4848/

And probably a few of these:
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Check_Valves/ES259630/

And you'll need some replacement clamps. You're mechanic might be able to supply those.

AudiNFS
08-22-2010, 08:53 PM
I think a shop would charge at least 2 hours to do it. There is a lot of small annoying clamps, and they may want to remove the intake manifold to do the job. The parts will be a little bit of money as well. You will want to replace all of the PCV stuff if you're going in that far. You'll probably want this stuff:

http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Breather_Hoses/ES5942/
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Search/Vacuum_Hose/ES4848/

And probably a few of these:
http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Check_Valves/ES259630/

And you'll need some replacement clamps. You're mechanic might be able to supply those.

Thanks so much for the help! is there anything else I will need besides those things or is that all? and also how much of each item will i need (quantity wise)? Also, will those 3 things fix/replace all lines? sorry for all the questions...

walky_talky20
08-22-2010, 10:17 PM
There are some more lines, but you didn't specify if you had an Auto or a Manual car, so that makes a difference. The items I listed there are very common to replace. You would need 1 of the kits, 1 of the vacuum line (15ft ought to more than enough), and at least 3 of those check valves. The vacuum line setups changed year to year a bit as well, so it would be a good idea to check out your car before ordering stuff, cause you never know.

27litres
08-22-2010, 10:33 PM
It doesn't sound as though he's all that mechanically minded, so he may not know where to check.

If you buy those parts as suggested and hand them to your mechanic (preferably an Audi specialist, as regular mechanics don't know German stuff very well) and tell him:
"I think I've got a vacuum leak, so I've bought these parts. Can you install the Brake booster hose kit and replace as many of the vacuum lines as this (15ft) hose will allow"
You should pretty much get the job done!

You might also ask him to "give the PCV system a check over and show you any problems". That way, you can still have control over the purchase of any PCV gear.
PCV is Positive Crankcase Ventilation - it gets rid of noxious gases and pressure build-up in the lower half of your engine and introduces those gases into the combustion system usually via the throttle body. It normally consists of a pressure relief valve and some hoses and tubing, but can be more complicated depending on the manufacturer and emissions requirements.

Also, what does a check valve achieve?

AudiNFS
08-23-2010, 04:20 AM
It doesn't sound as though he's all that mechanically minded, so he may not know where to check.

If you buy those parts as suggested and hand them to your mechanic (preferably an Audi specialist, as regular mechanics don't know German stuff very well) and tell him:
"I think I've got a vacuum leak, so I've bought these parts. Can you install the Brake booster hose kit and replace as many of the vacuum lines as this (15ft) hose will allow"
You should pretty much get the job done!

You might also ask him to "give the PCV system a check over and show you any problems". That way, you can still have control over the purchase of any PCV gear.
PCV is Positive Crankcase Ventilation - it gets rid of noxious gases and pressure build-up in the lower half of your engine and introduces those gases into the combustion system usually via the throttle body. It normally consists of a pressure relief valve and some hoses and tubing, but can be more complicated depending on the manufacturer and emissions requirements.

Also, what does a check valve achieve?

You're right I'm not that mechanically minded... :(

Getting that job done that simply sounds really good though. And having him check the PCV is a great idea instead of buying it right off the bat. Thanks for the help!

I do also wonder what a check valve achieves also... and where the 3 of them go and are used for. Also just to clarify, I have a manual trans, which i hope is better lol thanks again guys!

ECS Tuning-Audi
08-23-2010, 02:23 PM
You're right I'm not that mechanically minded... :(

Getting that job done that simply sounds really good though. And having him check the PCV is a great idea instead of buying it right off the bat. Thanks for the help!

I do also wonder what a check valve achieves also... and where the 3 of them go and are used for. Also just to clarify, I have a manual trans, which i hope is better lol thanks again guys!

Actually, vacuum lines are a good 1st thing to do for a new owner who wants to learn. Basically you get some hose, like the 15ft roll above, and you do one line at a time. Just check in the bay for hoses that have the same diameter and cloth coating on them. Pay attention to where they run to and from, remove it, cut your same hose to the same length - and repeat. It really isn't terrible!

Also, while you are poking around the engine bay you can inspect all your hoses to the PCV system like mentioned above. We have a few hose kits on sale too for less than 10 bucks (http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Hoses_-_Tubes/ES279586/?salesrep=CArmbruster&utm_source=audizine&utm_medium=forum&utm_content=CArmbruster&utm_campaign=postreply). They are breather hoses of popular diameters known to cause issues. The kit comes with hoses and clips, etc. It might be a good second step to pair with that roll of 15ft vacuum tubing.
http://c1552172.cdn.cloudfiles.rackspacecloud.com/94824_x800.jpg (http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Hoses_-_Tubes/ES279586/?salesrep=CArmbruster&utm_source=audizine&utm_medium=forum&utm_content=CArmbruster&utm_campaign=postreply)

Just some options! Don't be too scared by hoses - they don't have moving parts to break.

AudiNFS
08-23-2010, 04:21 PM
Actually, vacuum lines are a good 1st thing to do for a new owner who wants to learn. Basically you get some hose, like the 15ft roll above, and you do one line at a time. Just check in the bay for hoses that have the same diameter and cloth coating on them. Pay attention to where they run to and from, remove it, cut your same hose to the same length - and repeat. It really isn't terrible!

Also, while you are poking around the engine bay you can inspect all your hoses to the PCV system like mentioned above. We have a few hose kits on sale too for less than 10 bucks (http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Hoses_-_Tubes/ES279586/?salesrep=CArmbruster&utm_source=audizine&utm_medium=forum&utm_content=CArmbruster&utm_campaign=postreply). They are breather hoses of popular diameters known to cause issues. The kit comes with hoses and clips, etc. It might be a good second step to pair with that roll of 15ft vacuum tubing.
http://c1552172.cdn.cloudfiles.rackspacecloud.com/94824_x800.jpg (http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Engine/Intake/Hoses_-_Tubes/ES279586/?salesrep=CArmbruster&utm_source=audizine&utm_medium=forum&utm_content=CArmbruster&utm_campaign=postreply)

Just some options! Don't be too scared by hoses - they don't have moving parts to break.

I am scared actually. also I have no idea of how much time it will take to do all the hoses like I want. How many different diameter hoses will I need to do all the vacuum lines? it's scary for a first timer[>_>]

walky_talky20
08-23-2010, 09:06 PM
If you don't want to tackle it yourself, I'd suggest taking it to a trusted mechanic and get his opinion. After a quick visual inspection, he should be able to tell you what should probably be replaced, and how much he'd charge for that. Ask him specifically too look at at the condition of the PCV breather system under the manifold, and the condition of the check valves there as well, as it is common for them to visibly deteriorate, like this:

http://farm3.static.flickr.com/2387/2106368310_782baf009d_o.jpg

AudiNFS
08-24-2010, 04:16 AM
If you don't want to tackle it yourself, I'd suggest taking it to a trusted mechanic and get his opinion. After a quick visual inspection, he should be able to tell you what should probably be replaced, and how much he'd charge for that. Ask him specifically too look at at the condition of the PCV breather system under the manifold, and the condition of the check valves there as well, as it is common for them to visibly deteriorate, like this:

http://farm3.static.flickr.com/2387/2106368310_782baf009d_o.jpg

Will do! [up] Thanks a lot a for the help guys!

ECS Tuning-Audi
08-24-2010, 07:25 AM
Walky has a good idea, consult a mechanic and use your estimate and inspection as a way to gain some insight into what is involved in the process. There are also loads of DIY's for the job. You could use a PCV delete DIY article as a road map for how to replace your PCV system. Sometimes you just have to approach things backwards [up]


I am scared actually. also I have no idea of how much time it will take to do all the hoses like I want. How many different diameter hoses will I need to do all the vacuum lines? it's scary for a first timer[>_>]

Vacuum lines are all one diameter and the PCV system is all the other diameter. Basically, the cloth wrapped vacuum hose listed above is what you'd use for the vacuum lines and the kit I posted above is what you would use for your PCV system.

AudiNFS
08-24-2010, 12:29 PM
youre right. thanks! although im still confused what and where the in-line check are and go and what they're used for?

ECS Tuning-Audi
08-24-2010, 12:45 PM
youre right. thanks! although im still confused what and where the in-line check are and go and what they're used for?

You'd see them as you inspect your configuration. Basically they are valves that will only allow pressure through the system in one direction or at a certain PSI.

AudiNFS
08-24-2010, 07:47 PM
Like boost PSI or other PSI's? sorry for all the questions... i've been getting scorched for them lately.

walky_talky20
08-24-2010, 08:37 PM
Yes, the check valves allow vacuum to be applied to that part of the system, but won't let boost through. It is simply a one-way check valve, aka a non-return valve. It only allows air to flow in 1 direction, toward the manifold. These are very important on turbocharged cars as you don't want boost pressure to go to certain items. When they fail, they can cause all kinds of hard to find problems as your boost is leaking through them, or they create vacuum leaks to atmosphere, etc.

AudiNFS
08-25-2010, 01:20 PM
Okay thank you. I understand. Sounds great. thanks for all your help!

Accord4tehloss!
08-25-2010, 07:58 PM
Question some of my hoses look like they are worn and leaking, do you have to remove the intake manifold to replace any of the hoses?

walky_talky20
08-25-2010, 08:32 PM
People have replaced just about every hose on these cars without removing the manifold. That said, it makes it so much easier to do, especially if you are doing the PCV breather pipe / T-hose / PCV breather valve, etc. People have done it the other way, but I'm sure their hands have the scars to prove it.

Accord4tehloss!
08-25-2010, 09:00 PM
Ok cool thanks, I have an awm engine and replaced the t looking hose in the back of the engine and the l shaped hose both were soft and had holes in them bad enough with the windows down in first gear you could hear air escaping while in boost. drives much better now and installed my boost gauge tonight and peaks at 10-11 and settles at 9. But I noticed a few of the braided lines look bulged and leaky. So I am gonna replace them too. Can just buy some 3.5 vac hose from a parts store?

ECS Tuning-Audi
08-26-2010, 08:01 AM
People have replaced just about every hose on these cars without removing the manifold. That said, it makes it so much easier to do, especially if you are doing the PCV breather pipe / T-hose / PCV breather valve, etc. People have done it the other way, but I'm sure their hands have the scars to prove it.

No doubt. Many things can be done without following the Audi recommended steps. However, sometimes the stress of "wiggling" things out isn't worth the time savings of the shortcut.


Ok cool thanks, I have an awm engine and replaced the t looking hose in the back of the engine and the l shaped hose both were soft and had holes in them bad enough with the windows down in first gear you could hear air escaping while in boost. drives much better now and installed my boost gauge tonight and peaks at 10-11 and settles at 9. But I noticed a few of the braided lines look bulged and leaky. So I am gonna replace them too. Can just buy some 3.5 vac hose from a parts store?

You can, but be sure it isn't too spongy or malleable or you'll get awkward behavior in the system.