I am going to cleanup the EGR pipe in my VW Jetta TDI. Are there any special considerations on how to remove the carbon which might be blocking the flow?
Get a bunch of carburetor cleaner and some oil picks
Really, it's not a big job but it's a little nasty.
Having some metal mixing bowls to put the EGR into when you spray it down will help to contain the mess into a nice consolidated little package. Using some glovers as well is not a bad idea.
How I've done it and I've only done one.
Visually inspect it. Look for buildup that may block the operation of the vacuum valve. Ensure the vacuum diaphragm functions and the piston can retract. If it cannot, carbon buildup may be preventing it. Ensure the diaphragm is not compromised and can retain a vacuum. No splits, cracks or holes in the rubber.
Spray a bunch of carburetor cleaner into it. Pick away the chunks with the oil pick. Let the carb cleaner soak in. Wash, rinse, repeat.
When your done, you'll know it
You can use a mityvac to test the operation of the vacuum piston
Tools you'll need
Extension for socket
Old tooth brush