Re: intake manifold gunk (marsrocco)
To clean it, the only proper way to do it involves getting the intake manifold off the car. I have only done this on A3 and B4 engines, the A4 is a bit different, but the general idea will be the same.
1. Remove the engine cover and the various intake and intercooler pipes that are in the way.
2. Remove the outlet pipe from the turbo compressor. When you do this, the turbo will be somewhat exposed ... cover it with a clean rag to prevent anything from getting in there.
3. On the '96 B4, you have to remove the oil feed line to the turbo, it's in the way of one of the manifold bolts. Other models may or may not have this issue. The fitting at the turbo will probably be quite stiff. Be CAREFUL but persistent, once you get the threaded sleeve off, the line can be carefully but firmly popped loose if it's stuck. COVER THE OPENING in the oil feed to the turbo, and put the oil line in a clean place so that nothing will contaminate it.
4. Disconnect the EGR vacuum hose connection, and remove the EGR feed pipe. On models equipped with an EGR cooler, you can unbolt it from the back of the intake manifold (2 bolts) and swing it out of the way, no need to drain the coolant.
5. Remove the single bolt that holds the air intake pipe to the intake manifold. On A4-chassis cars, you might not have this, but you'll probably also have to disconnect the various things that connect to the anti-shudder valve.
6. If there's anything left in the way of the intake manifold, get it out of the way. If there's anything still attached to it, get it un-attached. Various models might have different minor issues here.
7. Remove the 6 bolts which secure the intake manifold to the engine. On some models the heat shield over the exhaust might partly block a couple of the bolts ... a careful tap with a screwdriver and hammer will solve it. Some of the bolts are tricky to get to, 6mm allen socket on some, 6mm ball-end allen wrench on others.
8. Clean out the manifold using suitable nasty solvents, glass-bead-blasting, high pressure water and detergent blast, or whatever works. Paint remover apparently works well, but don't get it near anything painted.
10. Re-assemble. Don't forget the oil line!
Check everything over before starting the engine, make sure that all fasteners are accounted for and properly tightened, make sure all electrical and vacuum connections are put right.
DO NOT attempt to clean the manifold while it is still attached to the engine. For one thing, you won't be able to get at the stuff further down. For another, if solid particles get into the engine, that's bad news.
This is a good half-day job for someone who knows which way to turn a wrench.
Brian P.
'96 Passat TDI mit UPsolute
