Tips for cleaning blow-by buildup from upper intake

[stickboy]

I am almost done putting my 99 4.0 SOHC back together. The one thing I have left to do on the engine before I hoist it back in is clean out the upper intake. There is a lot of burnt oil caked on the walls from (it appears) blow-by. I am wondering what the best way would be to clean it out, or if I should even bother. I have mineral spirits, but after soaking the lower manifold and some other parts, I still had to do an awful lot of scrubbing and wire brushing to get them clean. Obviously that's not really an option on the upper intake. I saw someone mention on a different forum that soaking it in gas overnight might work. Would that damage the plastic manifold though? What do you guys do?

 

[rb142]

Don't soak it in gas. That's just dangerous and probably not that effective.

Try a spray throttle-body cleaner or let it soak in something like Seafoam for a bit.

 

[2000StreetRod]

intake crud

Much of the accumulation in the intake manifold is due to EGR. I used throttle body cleaner but still had to do a lot of scraping and brushing. rb142's suggestion of using SeaFoam might be a good one since it is designed to clean valves and pistons. Check the instructions to make sure it doesn't damage plastics, etc.