Cleaning Gen III Intake Manifold

[coffeegoat]

I'm in the midst of my tear down for my engine refresh (timing belt, valve seals, head gasket, etc) and because I've only got a couple of hours at a time last night I finally got the air intake manifold off. It looks horrendous...





Certainly it needs a bit of a cleanup, but my question is how clean should I make it, and is there a best tool to do so.

My intention is to try simple green first, followed by brake parts cleaner to strip off as much of the varnish as I can, and then look upstream and downstream as much as possible for other stuff to clean up, is there a better way to do this?

Also, it seems dirtier than I would expect for an intake manifold, any thoughts on why?

 

[nwoods]

I've a similar discovery on my gen 2.5, actually mine looks worse. Theory is a bad EGR valve. Solution recommended by IncorporatedX was a cleaner called PurplePower.

 

[Schitzangiggles]

I used diesel fuel and then carb cleaner to clean mine. Purple power and like cleaner/degreasers are very acidic and will etch aluminum.

 

[montypower]

Warm dishwasher soap bath soak then brake cleaner. You can make it like new. It will look like this:

Good time to red loctite the butterfly valves.

 

[coffeegoat]

oooh, shiny!

I'm just finishing up pulling everything down to the heads, I'll start the cleaning and rebuilding this weekend, it looks like it should go well, if a bit tedious.