Hi,
I replaced the rocker cover gasket on my TDI when i changed the injector harness. Main hassle is getting the cabin inlet out of the way. You need to take the wiper and the cowling off to get at the fasteners coming from the top. Then the four nuts down where the inlet goes through the bulkhead.
Then its awkward to get at the back bolts which hold the cover down due to the proximity to the engine inlet and egr valve. Youll need a nuckle or similar on your socket set.
But essentially it is as straight forward as getting the stuff in the way, out of the way, and then unbolting and the gasket sits in the groove in the rocker cam cover and bolt it back up again. There is also some liquid sealant required between the cylinder head and the cam caps at each end to prevent seepage along that joint. Audi of course recommend their own sealant... whatever that is.
One word of warning for me would be if you suspect any corrosion whatsoever of the bolts replace them as they will snap when torquing up (speaking from experience here...). They also have an o-ring which is captive with the bolts, so it might make sense to change the bolts too as you'll get a new o-ring for that area too, it seals up into where the bolt sits in the cover. Or replace the o-ring if you have any handy.
Gasket was around 13 quid plus VAT i think when i bought mine, dunno about the bolts.
Hope this helps.
Gary
