So the 'ol girl is about to get torn down for her 180k mile timing belt plus a bunch of other things.

As I was trying to find an intake leak (turned out to be the S3 hose kit joint at the throttle body... clamp was loose), I noticed that when I reved the motor that the valve that runs the EGR ticks/clicks rather loudly. I don't ever remember it doing this before. When I pulled the vac hose off the valve going to the EGR, the vacuum pulsed w/ the clicks, so obviously it's from the valve opening and closing... but is it making this noise normal? or is my valve wearing out?

Thanks all! 'Ol girl is getting some major TLC... and I have to do some diagnosing to make sure I don't have a HG leak as I'm slowly losing coolant, and there are no visible leaks or the beautiful scent of coolant in the car.

wonder if the heater core is the coolant leak? i noticed in the last month or two i have needed to add about a quart total of coolant to the res.. its not in the oil and cant seem to locate any other places yet but i see it as another thing to add to my short list..

or seeing any leaking fluid in the cabin or fogging windows due to the coolant "mist"

Not impossible, mind you... but still unlikely me thinks.

We'll see what happens.

<center><img src="http://pictureposter.audiworld.com/57225/5_blue_silicone_seal_out_of_position.jpg"></center><p>
...what you could be hearing is it responding to being cycled by the ECU if the engine is warm &amp; not at idle. However I don't think this should be occuring at or near idle. If vacuum signal is being sent to the EGR valve while idling, perhaps your EGR F/V is already failing to seal closed, starting to fail, or intermittant.

My new freq. valve was quieter as my old one was quite degraded inside.

Is it wearing out? Possibly it has become contaminated. Have you done <i>the</i> mod? If not, yes it will eventually fail to seal engine vacuum. See succesive links starting below.<ul><li><a href="http://forums.audiworld.com/12v/msgs/65362.phtml">EGR Mod, what it does, why &amp; some proof...</a></li></ul>

it's not tossing any codes or anything and seems to be functioning properly... just wasn't used to hearing the noise.

I leave my EGR setup fully functional, so no "mod" there ;). It won't add enough power to even bother bypassing.

I'll keep my eye on it as time goes. I guess I'll replace it down the road. At the moment, I'm still trying to swallow the large pill that is all the stuff I got for my 180k maintenance... got a good deal on everything from Joe @ axismotorsport, but even w/ the good deal it was pricey due to all the parts I got!

tore the car down to the service position last night.

Did a compression check... all cylinders were 170psi or better, so that checks. Noticed residue around a coolant hose off the thermostat housing as well as possible coolant on the bottom driver's side of the radiator. Need to look closer tonight.

Her gifts will be:

New primary 02 sensors, new TB and associated goodies, new spark plugs, new accessory belt and tensioner, fresh oil and filter, new pass side valve cover gasket (lots 'o oil!), and a few other odds and ends... and a bath once she leaves the garage. That won't happen for a little while though as I'm waiting on all the parts as well as the crank locking bolt.

...(IMHO) the mod leaves the EGR System fully functional &amp; does not in any way "by-pass" or reduce its function, in fact the mod requires a fully serviceable system in order to work!

Myth busted: the EGR mod is not a performance gain, it's about preventing losses. If you want to <i>minimize</i> the EGR Systems operation (&amp; you might, unless you enjoy cleaning out <i>that</i> passage-way more often), see below.

The original EGR mod's true benifit is not what its stated purpose was. Its entire effect is <u>only</u> to prevent the otherwise inevitable ingestion of contamination (sucked in via your intake system) from destroying the subject (already noisy) EGR Freq. Valve; &amp; thus preventing the often associated engine idle &amp; power loss symptoms, CEL's etc. <u>due</u> primarily to said valve's failure.

That the mod <u>won't</u> work once your EGR F/V is ruined points to its' need to be done prior!

This is almost the definition of preventative maintenance, except it's the simplist of mods, no down-side &amp; one of the most cost-effective. Bother!<ul><li><a href="http://forums.audiworld.com/12v/msgs/62639.phtml">EGR System operation minimized...</a></li></ul>

it removes parasitic loss instead... in essense "freeing up" ponies required to operate the above mentioned items.

On the other hand, I disagree that doing the EGR mod leaves the system 100% functional. By removing the vacuum line from the valve, you in essense stop that valve from cycling the EGR to allow gasses into the IM... so while the system is intact, it is not functioning as designed.

I'm not sure if it's me or what, but I have not had a single issue w/ my IM EGR passageway crudding up. The car has been in the family since new. When I R&amp;R'd the IM to install the TDL IM, the passage was not blocked, and when I R&amp;R'd the IM again to R&amp;R my valley pan gasket, it again wasn't even close to being blocked... so I have no issue with leaving it fully intact and 100% operational.

also, to be clear, the vacuum valve is what's ticking, not the EGR on the exhaust. Wasn't sure if I was clear on that or not.

<center><img src="http://pictureposter.audiworld.com/57225/vacuum_diagram_bulletin_in_color_website.jpg"></center><p>...it's a vacuum <i>relief</i> line. See "Atmospheric pressure" (Black line) in illustration above. This is the subject hose of "the EGR Mod". It routes atmospheric pressure (not vacuum) to the EGR F/V which, if serviceable, allows the EGRV to <i>close</i>.

Atmospheric pressure is <u>not</u> the control pressure (delivered via the Brown line) used to activate the EGRV, <u>vacuum</u> is (see the dark green line), therefore, there can be no change to EGR System function by dis-connecting the Black line. Besides, it just wouldn't make sesnse to have <u>two</u> sources of vacuum to try to close the valve, when vacuum is only used, to open it.

Notice also that the Black line connects, at its' other end, to the Noise-Damper, upstream of the Throttle-body Butterflies, it therefore sees no meaningful engine vacuum. It only follows then that it has no vacuum, to deliver.

Consider also this: Every Ford V6 van I've looked at comes factory equipped with <u>our</u> EGR Mod <b>done</b> to it already &amp; with a small air filter installed where "the EGR Mod" has an open hose! Do you think their EGR valves function less than they intended?

Thanks..

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In this one, the subject line is called the "egr vent line" as opposed to "vac supply".

Only by "venting" the vacuum (supplied via the "vac supply" line) used to open the EGR Valve (it's normally closed) , can it return to the closed position, unless there is a leak.

The clicking you may hear coming from the EGR F/V is it switching from supplying vacuum; to venting that same vacuum, to atmosphere.

but I coulda sworn I only had this line only going to the EGRFV.

That being said, and maybe it's different w/ my recovery sleeve setup vs the stock plenum, but there's def vacuum coming from the line on the recover sleeve. I don't see how there wouldn't be considering that air would be pulled through it... then again, i've been wrong in the past ;)

I'll test it out just for my own amusement once I get the car back together... it's kinda... indisposed at the moment :-O

<a href="http://picasaweb.google.com/jretal/A4180kTimingBeltMaintenance/photo#5210821959128144338"><img src="http://lh6.ggpht.com/jretal/SFCO9rWjWdI/AAAAAAAAAHE/HHRaDYPMva8/s800/IMG_3139.JPG" /></a>

<center><img src="http://www.jtnicols.com/audi/coil_overs.jpg"></center><p>
... still have your 4000? I talked to this fellow (very nice guy) about his excellent looking dampers/struts/<u>sphericalled</u> strut-top bushings etc. (gone), he may have a prepped 4000 engine(?) &amp; other interesting stuff(?) from his rally car that he'd like to see go to a good home, for only a very few $. I said I'd pass it on.<ul><li><a href="http://www.jtnicols.com/audi/audisale.htm">Audi Coupe GT Rally Car Parts for sale</a></li></ul>

have mance's coilover sleeves w/ sphericalled strut mounts, eibach springs, boxster calipers, MC1 turbo block w/ NF head w/ oversized exhaust valves, 2871 turbo, 3" exhaust and a stand alone ecu, and a whole slew of other stuff :)

It's got some kick and it's the main reason why i'm really not interested in making the A4 any quicker, just comfortable and reliable. A simple twist of the boost knob and I leave the A4 sitting in the dust. I realize why the turbo guys love 'em so much, though I still wouldn't trade my 12v in for anything.

...I'm supposed to be workin' on the Coupe, <i>it's</i> the summer car &amp; all, but I'm having so much fun driving that 2.8!

that and I still love the looks on people's faces when I tell them that it's a '96 and has 180k on it ;) Def doesn't look that old!

our 12v were the first series of A4's and they imported the B5 A4 for 5 years so it could as far as anyone knows be a 2001 but i bet they dont even know that it might be only a couple years old to them..