My 09' A6 3.0T Prestige

[christianb5s4]

Hi everyone. I frequent the B5 S4 section and am seriously considering buying a 2009 A6 3.0t Prestige w/ 80K this weekend, seems like a clean 2 owner car. However, I've been doing a ton of research to see what problem areas there are with these cars. So far I've amassed the following main ones:

- Oil consumption
- Plastic coolant pipes
- Oil consumption (appears mostly PCV and oil separator related)
- Valve cover gaskets, timing cover leaks
- Vacuum pump leak

Am I missing anything else important? Thought I'd check with you guys who're much better experts than I before taking the leap

Edit: Now own said car, this will be an update thread for anyone interested in it.

[11A6]

Carbon build up on valves etc. - it's going to be an issue with any Direct injection engine - unless it also has port injection like some new cars do. May not have immediate need to get it cleaned out but )

[B. Rock]

Plan on an immediate trans fluid + filter change. 75k is the interval ZF recommends, so you can bet at 80k it hasn't been done.

Otherwise that seems about right. MMI issues on occasion if things get wet.

[christianb5s4]

Do you recommend the Audi replacement fluid? The pre-assembled kit on ECS is pricey with the Audi fluid, for example I use a different than OEM fluid for my B5 S4 (Fuchs Sintofluid).

[B. Rock]

That's entirely up to you. I went with OEM fluid 2x now, as it's still cheaper than a new trans. I got it from: http://www.thectsc.com/ . They can run the vin and tell you if you need yellow/green/blue/whatever.

The fluid for the center diff is even pricier, but you need way less. I think the rear diff was regular 75-90W IIRC.

[cal3thousand]

Thermostat is guaranteed to be an issue if not previously replaced with the updated version. You might was well do it when you do the PCV. Do the water pump and clean out the carbon in the intake ports while you're in there too.

On the subject of the PCV, I found a seller on eBay that sells just the rubber membrane so you don't have to replace the whole housing. I have received mine and am planning to do the job in the coming weeks.


EDIT: B. Rock's advice above is spot on too. I bought mine from the same site. Got a full case to save money. The front and rear diffs can be Redline 75w 90 fluid but the center diff needs the special unicorn blood.

[christianb5s4]

Here's some additional background on the car I've gathered, some of the bigger services that I've called each dealership to confirm was completed. This car has the most detailed Carfax I've ever ran and has only been serviced at dealerships it's whole life.

This is a run down of what's been done in terms of service intervals (all at various Socal Audi dealers):
- 5K service done (8/2009)
- 15K service done (6/2010)
- 25K service done (2/2011), also new brake pads and brake fluid
- 45K service done (1/2013), includes transmission gasket replacement, air vent outlet replaced, brake fluid flush

Now here's where it gets interesting:

- 10/2013: Engine compression checked, cylinder head gaskets replaced, cylinder head replaced
- 11/2013: Radiator replaced, general service

I wonder if the compression check and cylinder head services above are related to oil consumption fixes?

[SinCityA6]

Head gasket and new head would not be a standard oil consumption issue. That is an extraordinary fix if it was. Head gasket and head replacement is more in line with a severe overheating issue (hence radiator replacement). I was good with everything on the car until I read that.
The only other pending issue to consider is the harmonic balancer/lower pulley issue. I suggest replacing that prior to a failure which will happen sooner or later.

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[TheAlphadog]

I have a 2010 A6 C6 that, within a year after I got it, the thermostat needed replacing @ 55K miles. The service records showed that it was replaced once before, under 10K and under warranty (fwiw). I factored in the cost of it happening again, and it did, sooner than expected.

I have had no oil consumption issues with mine. I get the oil changed once a year (I drive this car less than 10K a year). The only other repair was valve cover gasket replacement at last oil change. I did the spark plugs myself.

Now, with the car you are looking at, I would want to dig a bit more into what seems like a severe overheating issue. And, if head gaskets, cylinder heads, etc were replaced, why is there no service record of the thermostat and water pump being replaced?

You may want to consider taking the car to an independent mechanic if you are serious about it. Definitely get a compression check. Also have them check for seeping valve cover gaskets and the condition of your belts.

If you pull the trigger on the purchase, consider holding aside $1000 to $1400 in thermostat & water pump replacement (if that strikes again).

[christianb5s4]

2009 A6 3.0t Prestige, 80K miles, 2 owner Phantom Black and black/brown 2 town interior. So nice to have a comfortable, solid reliable daily car (knock on wood). I'm pretty handy with mechanics skills through my built B5 S4 but the car feels very solid and is extremely clean, more so after I spent all of yesterday cleaning and picking through it. As for the head replacement, I called Audi Mission Viejo who did the work and they confirmed a new head was installed along with a head gasket so I'm not too worried about it.

That said, I can smell coolant when the car runs (even in 90 degree temps stuck in traffic, coolant temp was dead center) but there is no evidence of any coolant in the intake valley under the supercharger nor is there any leaking from the water pump area. I topped off the coolant and will monitor levels

Here's what I've ordered so far and will replace first and foremost, let me know if I missed anything:

- N80 valve and new gas cap (car has typical PO0441 code)
- Supercharger belt and serpentine belt
- Thermostat
- PCV
- Sparkplugs
- Cabin and intake air filters
- Intake air filter







And at my office, taking the S4's spot:

[christianb5s4]

Also, want to replace the oil separator under the supercharger while it's off for the thermostat. Can anyone confirm this is the right one? https://www.ecstuning.com/b-genuine-...m/06e103547ac/

[B. Rock]

Looks to be correct. For things like this, I use the Audi site.

https://parts.audiusa.com/p/Audi_200...E103547AC.html

Also, it showed at $121 at my local dealer.

Lastly, I didn't think these an an N80 valve?

[christianb5s4]

The 3.0Ts do, it's under the cover with the Audi rings. This is the part and it's somewhat common issue since Audi/VW use the same N80/Purge Valve across many cars and a failed one always results in the PO0441 code (https://www.ecstuning.com/b-genuine-...ve/06e133781a/) part # 06E133781A. Here's a picture pointing it out:

[christianb5s4]

Put in a few big orders to tackle every single maintenance point needed on this car. Goal is to get everything taken care of upfront to make the car a rock solid daily for many years to come, including replacing any possible 3.0T trouble points as preventative work. List of items so far (including part numbers in case it helps anyone), car will be going under the knife next week.

General Items:

06E133781A Purge Valve N80
4F0201550J Gas Cap
101905611G-6 OEM NGK spark plugs
06E903137AB Supercharger belt
4F0133843 Intake filter
06E105251F Crankshaft pulley
N91005902 Crankshaft pulley bolts x8
Serpentine belt
Cabin Filter

All Items related to PCV overhaul:

06E103213 PCV Vent Tube
06E998907E Fuel injector repair kit x6
079129717B Lower intake manifold gasket x6
079129717D Upper intake manifold gasket x6
N90316802 Coolant sender o-ring
06E103217AD PCV Hose
06E103547AC Crankcase PRV

[marketdemon]

you may want to add a coolant crossover pipe to that list. That ended up being the culprit when I had coolant problem. With all that work going on, I'd recommend doing the water pump at this time too since you'll already have most of the parts out of the way which should make both those repairs very easy. ESC has some great water pumps for well under 50 bucks, but there is no aftermarket part for the crossover pipe. OEM only, and again from ECS I think that one is about $225 to 230. Car looks great.

[christianb5s4]

you may want to add a coolant crossover pipe to that list. That ended up being the culprit when I had coolant problem. With all that work going on, I'd recommend doing the water pump at this time too since you'll already have most of the parts out of the way which should make both those repairs very easy. ESC has some great water pumps for well under 50 bucks, but there is no aftermarket part for the crossover pipe. OEM only, and again from ECS I think that one is about $225 to 230. Car looks great.

I'm going to add those to the list, I want to do everything now and not worry for a long time. I also got the typical rear tail light out message that seems to be relatively common due to the internal contacts in the tail light degrading over time, I cleaned all contacts and used dieelectric grease but no dice so I ordered two new OEM outer tail lights. Weird thing is the light is completely functional even though the car says it's out.

[c@@kieMonsta]

Head gasket and new head would not be a standard oil consumption issue. That is an extraordinary fix if it was. Head gasket and head replacement is more in line with a severe overheating issue (hence radiator replacement). I was good with everything on the car until I read that.
The only other pending issue to consider is the harmonic balancer/lower pulley issue. I suggest replacing that prior to a failure which will happen sooner or later.

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Mines at 72k. How hard is it to do that harmonic balancer replacement?

[christianb5s4]

The time to do it is if you're replacing the belts, it's relatively rare for it to fail but if you're having the belts replaced you might as well do it even if it hasn't failed yet.

[SinCityA6]

The time to do it is if you're replacing the belts, it's relatively rare for it to fail but if you're having the belts replaced you might as well do it even if it hasn't failed yet.

It is not relatively rare for it to fail. This is an absolute occurrence. Very well documented in the B8/B8.6 S4 threads. It becomes especially true when you tune the car.


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[SinCityA6]

Mines at 72k. How hard is it to do that harmonic balancer replacement?

Sorry @c@@kiemonst, I couldn’t tell you as it was done by my mechanic.


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[c@@kieMonsta]

Sorry @c@@kiemonst, I couldn’t tell you as it was done by my mechanic.


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What'd it run you?

[SinCityA6]

Since it failed and took all the belts with it, about $1400 all in.


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[cal3thousand]

I've been seeing solid cranks pulleys for our cars recently. There's a claim that the balancer's dampening was only for NVH reasons and not for motor longevity. Anyone here got one?

[christianb5s4]

I bought the OE Audi/VW crankshaft pulley from ECS which was $400, I'm doing all the belts and water pump at the same time as well as the oil separator, PCV, carbon cleaning etc. Labor is going to be $700 for everything.

If you were just doing the pulley I'd imagine it's $200-300 for labor depending on where you take it and how familiar they are with the 3.0T. FWIW, I researched at length crankshaft pulleys for my built B5 S4 and ended up with a new OE item. You could go the Fluidamper route but I highly recommend not going for a solid pulley, NVH is the least of your concerns. It helps dampen harmonics that would otherwise be transmitted through the engine's internals and could cause increased bearing wear.

[christianb5s4]

Got some work done on the car yesterday. Installed new OE NGK sparkplugs gapped to .030 (old ones were in decent shape but clearly used), installed a new Audi intake filter, and tried tracking down the EVAP leak but had no luck. Car goes in Wednesday for a whole bunch of stuff so I'm looking forward to having everything that can be addressed taken care of in one fell swoop.

[cal3thousand]

Reading back through your thread, I realized that you mentioned coolant smell.

If that's the case, it could be the heater core leaking into the cabin. Check under the carpet mats up front and make sure there aren't any leaks up there. Is your coolant level staying good?

[christianb5s4]

No smell in the cabin at all, only in the engine bay, no visible leaks, no steam and can only smell it if the car is run up to full temperature. The tray under the engine is dry and nothing is reaching the ground. Coolant level has stayed pretty consistent since I topped it off early last week and there's no smell through the vents regardless of AC or heat.

[11A6]

My 11 A6 has same exact smell but no observable symptoms of coolant leak - @ 3.5k I had to add quart of oil so PCV update is on agenda once it warms up in Northeast.


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[christianb5s4]

What I've found through research is the water pump on the front of the motor can develop a slow seep over time, not enough to leak to the ground most of the time but it's there. I can smell coolant most strongly at the front of the motor. But no biggie as the car is getting a new Audi/VW OEM water pump so that will fix it.

[11A6]

Have you have oil checked with Blackstone or similar - I've seen some people have coolant/oil mixture and wondering if that's an issue - I will be doing this when I have first oil change in a couple of months.

[christianb5s4]

I haven't, I'm doing an oil change this week so will save some to get a sample done I believe.

[christianb5s4]

Dropped the car off at a local Audi independent shop that's been great with my B5 S4, time to knock out a fairly long to do list. All this is preventative maintenance as the car runs great save for the EVAP issue which I suspect is a bad check valve in-line to the purge/EVAP valve. Spending more than I anticipated but I wanted to get everything done now rather than wait, always operate under the assumption that if you don't have irrefutable proof maintenance items have been done to a car prior to your ownership, assume they were not done.

Other than that it's getting the following:

- Supercharger & serpentine belts
- Crankshaft pulley and new bolts
- PCV hose, oil separator, PCV connector
- All new injector, upper and lower intake manifold gaskets
- Thermostat & OEM water pump
- Audi trans fluid and filter
- Oil change and filter
- Diagnose/fix EVAP

[l0uietheking]

Congrats on the car love the interior color and good luck with all of the maintenance, I was in the same place as you last year and have been tackling a bunch of these maintenance items as well, unfortunately my supercharger belt snapped because my harmonic balancer went bad right around the 100K miles so it's good that you're doing that now. It ended up being quite expensive to get the car back on the road about $1000+.

I still have an oil leak from my rear timing chain cover or rear main seal and possibly pcv system issue which I need to tackle but my car was just crashed into last week so I have to take car of that first.

[christianb5s4]

Thank you for the kind words, unfortunately some of the items that are important on these cars are not expensive on their own but expensive because you might as well replace a bunch of other things while you're in there. Case and point is the oil separator; supercharger has to come off, so might as well do the thermostat, carbon cleaning, PCV stuff etc. at the same time. Another case and point; are you doing the supercharger and serpentine belt? Might as well do the waterpump and crank pulley while you're in there.

But hey, it's cheaper to do things before parts fail than clean up after the fail! Couple updates on the car: we found a few issues outside of the items on the to-do list that were in need of replacement and are being taken care of.

- 06E103207AM breather tube with an integrated check valve to the purge/N80 valve that was leaking
- 06E121058E Coolant hose the shop found was leaking slightly due to a tear by the clamp on one end