A few issues I could use some help with.

eightrac · Oct 27, 2009

I have a '97 2.8QM that has a couple of issues I could use some advice on repairing.

My cruise has been out since I bought the car. I figured it to be a faulty vacuum line as all of them were bad. I replaced them all and it still doesn't operate. I recently found that my clutch switch is not working as I can start the engine with the clutch out. Could this be the issue or are the systems unrelated? If no, where should I start looking for the problem?

My car has the 12v 2.8 (AFC). It has about 102500 miles on it as of right now and currently burns about a litre of oil between 5000 mile oil changes. Is this normal? I use Mobil 1 5w-30 with Mobil 1 oil filters. I also can hear what sounds like piston slap from the #6 piston under no load conditions @ 2200rpm. Any ideas what that could be? I'm sure I'll be looking for a rebuild or replacement engine soon. That said, I have a couple other related questions to add to this subject. As you know, the 30v (AHA) engine appeared in '97 along side of the 12v (AFC) engine in the a4 line. Can I swap my 12v for a 30v provided I have the correct engine harness and ECM?

Thanks ahead of time.

s4marsh · Oct 27, 2009

i always use the clutch when starting the car out of habit but wasnt aware they're not supposed to start if you dont use it??

eightrac · Oct 28, 2009

I didn't know if these cars had a clutch switch to not allow in-gear starts. I guess that started in '98 according to audizine.

aragorn · Oct 28, 2009

I've never heard of a starter interlock on manual cars in the UK, only autos.

The cruise on your 12v will be the older vacuum system, and theres quite a lot that can go wrong with it. Theres a nice diag guide on either audiworld or audizine that i used to get mine working after the retrofit.

Basically it comes down to either the stalk contacts being dirty and not operating correctly, the vacuum pump having failed, the module having failed, or brake/clutch switch adjustment.

The diag guide takes you thru testing the stalk/switches and the pump, and if all that checks out then its probably a module fault.

Siena · Oct 28, 2009

All US cars require the clutch pedal to be depressed, to allow the engine to crank over.

The later 30V engine will fit, and should be plug and play, if from a '97 / '98 car. As the B5 had no immobilliser in the US, you shouldn't have any coding issues.

Siena · Oct 28, 2009

Another point - 5w-30 oil is a bit on the thin side, for an engine with that mileage.

I would run 15w-40 instead. It will raise the oil pressure slightly, and reduce consumption too.

aragorn · Oct 28, 2009

I'd suggest a 5w40 would be better.

Same rating when cold so your getting maximum cold start protection, but a little thicker when hot to keep the pressure up?

15w40's tend to be low quality mineral oils rather than synthetics?

Blue_Thunder · Oct 28, 2009

My cruise control was intermittent when I first got the car and hasn't worked at all in the last 3 years.

I plugged Laptop in and tested the cruise control switch positions and found them to be giving erratic readings. Not sure if that means the stalk is knackered or if there is a problem where the loom connects to the ECU, etc. Might be worth you running the same test though just to rule out those things.

Siena · Oct 28, 2009

15w-40 is not necessarilly a low grade oil. It is also possible to get low grade 5w-40. An engine that's clearly using oil, and at that mileage should actually be run on semi-synthetic, or non-synthetic.

aragorn · Oct 28, 2009

Siena: Why would the oil being synthetic or otherwise affect how much the engine burns?

Whether its fully synth 0w40 or 15w40 mineral oil, they're both exactly the same thickness when hot, so would seep past rings and suchlike at the same rate

Lee Goodall · Oct 28, 2009

..and the oil debate begins once more lol

audinary · Oct 28, 2009

I like Crisp 'n dry.

Lee Goodall · Oct 28, 2009

..Momma don't like no greasy oil la la

Siena · Oct 28, 2009

Aragorn, synth / non-synth can come in any viscousity, yes.

But a 5W-40 oil is a bit on the light side for an engine that's already suffering from blow-by, and with high mileage.

jcb · Oct 28, 2009

aragorn said:
15w40's tend to be low quality mineral oils rather than synthetics?

think this is what he was replying to

aragorn · Oct 28, 2009

Kinda. What i'm referring to is that a 5w40 and 15w40 are exactly the same thickness once the motor is up to temperature.

Once the engines up to operating temperature you ignore the bit before the W, so a 0w40, 5w40, 10w40 and 15w40 all act like a streight monograde 40 weight.

So saying a 5w is worse because its thinner isnt true, its only thinner than a 15w oil when its cold, and a cold 5weight is still thicker than a hot 40weight, so it makes no difference bar the cold start protection.

s4marsh · Oct 28, 2009

sienna v's aragorn

clash of the titans.....lol

who knows more....you decide! no offence guys

eightrac · Oct 29, 2009

A quick email to audi-america has quelled my concern over the oil consumption.

They claim ALL 2.8/2.6 engines consuming up to 1.5L between oil changes (5000 miles) are to be declared "normal" comsumption rates.

You should see the allowed limit for the 1.8T. Its in upwards of 1.75L.

aragorn · Oct 30, 2009

In this country the limit is usually 1L per 1000miles, however any engine burning anywhere near that much is completly knackered.

Our 1.8T uses about 1-1.5L of oil per 5k, but then its done 192k so its kinda to be expected!

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