Audi V10 repairs

[Flexray]

I did a bunch of repairs on this Audi 5.2L v10. For a v10, this thing is not super powerful. But I actually really like this engine.

The vehicle came in for a check engine light and a inspection. It set a cylinder 9 misfire code and a knock sensor 3 signal low amplitude trouble code. I find a bunch of the ignition coils are only half way plugged in, especially cylinder 9. I remove coil 9 to inspect the spark plug. The plugs are OK, but many of the spark plug tubes are full of oil. The valve cover gaskets are leaking into the spark plug tubes. I plug in the coils all the way, and no more misfiring. In the very front of the engine, there is the electrical connectors for all 4 knock sensors. Two of the sensors have breaking wires at the connectors. I recommend replacing the valve cover gaskets, the two knock sensor connectors, and a few other non-related things. The customer also wants the intake valves walnut blasted. I get approval and start the job.

I'm about to remove a lot of fasteners and parts from this vehicle, I need to be organized and focused on what I'm doing. As I remove components, they get stacked on the shelf in chronological order with their fasteners. I remove the front bumper cover, bumper bar, headlights. I unbolt the radiator support and move it forward to gain access to the front of the engine. I start with removing all of the hoses then the wiring harness. I pay attention to how things are routed. I will mark connectors/hoses with paint pen and or take pictures if something looks like it could be mixed up. I remove everything from the intake manifold and valve covers. I now remove the intake manifold off of the engine.


I find a small plastic piece stuck in cylinder 7 intake port. I inspect inside the intake manifold and find the variable intake runner flaps are broken. I recommend replacing the intake manifold. I'm told the manifold is $7000, and the customer doesn't want to replace it. I open up the intake and fully remove the intake flaps and clean all of the sludge out of it. The intake flaps create a long narrow intake runner that accelerates the intake charge that helps with cylinder filling at lower engine speeds. At high engine speed/load the flaps open and create a short fatter runner. The intake will now have the short fat runner all the time. The engine will loose some low end torque. I leave the flap actuator on the manifold so it doesn't set trouble codes and silicone a plug into the empty hole where the flaps were.

[Flexray]

Port injected engines have the injector spraying right onto the intake valves. Direct injection sprays right into the cylinder. The fuel spraying right on the intake valves keeps them clean. With direct injection there is nothing to keep the intake valves clean. Cylinder blow by gasses get routed into the intake manifold to be burned. Bits of oil and carbon collect on the intake valves and ports. Exhaust gas recirculation gets accomplished by opening the intake valves right at the end of the exhaust stroke. This pushes a bit of exhaust up into the intake port, then as the piston travels down it's bore on the intake stroke, it pulls in the exhaust and a fresh air charge. Having the intake valves passing exhaust gas also fuels the carbon build up.


The carbon builds up on the valve stem. Once enough builds up, it will hit the valve guide and hang the valve open slightly. This causes a misfire and a weird popping sound as the compression gets blown into the intake manifold. Built up carbon can also set rich fuel mixture or air mass trouble codes. The carbon restricts the amount of air that can flow into the cylinder. You remove the carbon by blasting ground walnut shells into the intake ports. Turn the engine over by hand until as many as possible intake valves are closed, tape off the ports with open valves. The blaster has an adapter that fits into the port, connects to a shop vac, and has a hole for the walnut blaster wand. Clean the intake ports. Rotate the engine until the remaining ports have closed valves then clean them also. I remove moderate to heavy amount of carbon. About 5mm think in some places.


I remove both valve covers. Give them a clean and install new gaskets into them. I clean the cylinder head sealing surfaces and the spark plug tubes. I install both valve covers. I give the engine valley a clean and install the intake manifold with new gaskets. I replace the two knock sensor connectors. I get the engine all back together. I start the engine and let it run for like a minute, before I fill the coolant and put the rad support back. If I forgot something or something is not right I want to know about now. Everything is all good, I install the rad support, bumper and cover. I vacuum fill the cooling system and let the engine run until the thermostat opens.


I'm about to take this vehicle on its maiden voyage. I modified the intake manifold, it is going to flow less air at idle and low rpm's. I put about 15km on the car while watching the idle and partial load fuel adaptations learn. They are -2%, this is ok, no trouble codes are going to set. The engine runs very smooth and has good power.


I had to wait for some parts, and I got pulled off of this job repeatedly. Which killed my efficiency. But I spent about 20 hours doing this job. Cleaning intake valves are actually one of my favorite jobs. I enjoy diagnosing the problem, cleaning the valves is very satisfying, and the engine runs so much smoother and has much more power than before.

[Ca_Silvia13]

How many KM's on the motor? Shocking to seem that much build up.

[Flexray]

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How many KM's on the motor? Shocking to seem that much build up.

170 000km

[Maxx Mazda]

Good work!

[bjstare]

That was an interesting read.

Also, a great case for buying the best example of a car that you can afford when going used vs. going the budget route, and possibly getting a car where the owner intentionally decided to leave it broken even though the engine was torn apart for other work

[JustinL]

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170 000km

This is fantastic. I'm sure that car has been very well enjoyed.

[Masked Bandit]

I don't know anything about fixing engines, but that looks damn masterful! Guys that can do stuff like this should make as much as doctors.

[BavarianBeast]

awesome rebuild, I’ve heard these engines are nightmares compared to the R8 V10

[g-m]

That's super cool

[SJW]

Do I need a v10 in my life?

[LilDrunkenSmurf]

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That was an interesting read.

Also, a great case for buying the best example of a car that you can afford when going used vs. going the budget route, and possibly getting a car where the owner intentionally decided to leave it broken even though the engine was torn apart for other work

I'm torn. It'll obviously cost to go back in, but $7k for an intake manifold is a lot of money.

Either way, love the photos and write up.

[bjstare]

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I'm torn. It'll obviously cost to go back in, but $7k for an intake manifold is a lot of money.

Either way, love the photos and write up.

I'm a moron and just assumed this was an R8. I was thinking it was weird he was taking the front bumper off . There's zero chance I'd buy a $7k intake for an S6 (?) haha. I actually probably wouldn't have done any of this if it was my S6, I'd have sold it to someone in the NE and moved on with life.

[LilDrunkenSmurf]

I knew it wasn't an R8, because the engine is in the front, but wikipedia tells me it could be an S8/S6/RS6. I want to assume this is an S8.

[Flexray]

The car was a 2011 S6.

Fixing this engine in the S cars is a bit easier than the R8. But not by much.

[94boosted]

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I'm a moron and just assumed this was an R8. I was thinking it was weird he was taking the front bumper off . There's zero chance I'd buy a $7k intake for an S6 (?) haha. I actually probably wouldn't have done any of this if it was my S6, I'd have sold it to someone in the NE and moved on with life.

I LOL'd pretty hard. Sorry but "You must spread some Reputation around before giving it to bjstare again."

[zipdoa]

Damn, that's a lot of work. I was never a huge fan of the N/A V10 VAG stuff but the C6 RS6 with the twin turbo v10 is on the hit list lol.

That manifold is big money! Pretty easy to find new for less than $7k but $2500USD is still a lot of money:

https://www.moddedeuros.com/products...fold-701116080

[Sentry]

Mini hijack:

I'm just buttoning this V10 R8 up at work. I built these headers from scratch, 2.0" primaries with 5-1 collectors, also putting on a VF supercharger kit at the same time.



Your eyes don't deceive you, the whole engine is offset to the left of the car a couple inches to make room for the front driveshaft. Made the driver's side header clearance very tight.

[SJW]

Do you have to balance the weight some how?

[Sentry]

Audi did when they built the car I'm sure