Tstealth32

2008 A8 4.2 FSI 144,000 miles

I'll be walnut blasting the intakes shortly. While I have everything apart, I'll also change out some other gaskets and parts.

Here is what I have so far:
Intake manifold gaskets
valley pan gasket
Both valve cover gaskets
Oil filter housing double Oring and single Oring
PCV fine oil separator
oil check valve
Oil spray valve
And adding an oil catch can

Anything else I should replace while that's all apart and easy to get to?

Thanks

MP4.2+6.0

Suggestion: figure out where coolant sensor is. On port 4.2 it was in a metal water line running across back of motor low down. If still in same place, way easier to get at with intake off. Sort of a "when not if" part as the motor gets older.

Plan to clean the throttle body with the assemble out and easy to access, and perhaps ditto for the MAF w/ some MAF or electronic (no residue) spray cleaner.

Tstealth32

Good suggestion. Looks like part coolant temperature sensor # 06A919501A. There are 2. One in the rear that you suggested, and one up front.

TSHong

How about a thermostat if you already have not done one yet? Also Injector orings since they are cheap.

Sci-fi_Wasabi

Would you mind posting a picture of before walnut blasting and after. i'm just wondering just how gunky the valves look in an '08.

Thanks

Tstealth32

144,000 miles on the FSI engine.
Oil valley pan gasket and double Oring oil filter housing gasket leak.
Failed fine oil separator caused a lot of oil inside the intake manifold.

Tstealth32

Valves have been walnut blasted and scrapped. The carbon was so thick in 2 of the valves that I don't think much air was even getting by. By the time I scrapped the walls and the valve, the intake was full of carbon. Then I did walnut blasting, soaked it with oven cleaner, scrapped, more blasting, and wiped it clean.

I got the valley gasket and oil filter gasket changed, as you can see, there was a big leak.

Put it all back together, went to start the car, and it kicked and bucked. Lots of misfires. Cylinder 1,6,7,8 all misfires, throttle sensor errors, manifold flaps stuck closed. Cleared everything, restarted the car, less bucking, misfire on #1 only. Cleared faults, revved it up, smoothing out. Cleared codes one last time, started it back up.....smooooooth as silk!

Hit the road, and the power is back!

Sci-fi_Wasabi

thanks for the pics! I had no idea it would be that gunky. Now I'm all paranoid that that is what mine looks like inside too. I'd probably do that if something else goes bad that involves manifold removal. I did change my fine oil separator without removing the manifold.
thanks again

richard-tx

And that caused the majority of the excess carbon buildup.

Tstealth32

Yes, that was a big factor. I have the stuff to add an oil catch can. It'll be interesting to see how much oil it catches.

I also have the equipment and additives to do the BG induction cleaning. I ran 2 cans through my intake, plus their gas tank additives (yes, I know the gas tank additive does nothing for FSI, but it's what they do at the shop). This was done a couple months ago, as you can see, it's a complete waste of money once the carbon has built up. However, I will start to do this every oil change now that my valves are clean.