I've seen this on a few trucks heads at the junk yard, and I do believe I have a similar condition I checked through the Air temp sensor hole and the sensor end and the inside of the tube is caked with build up. Looks like someone spackled the inside with the crunchy grease drippings from my grill. I have tried Sea Foam, no noticable difference. Is there a preffered manual way to do it? I was thinking of closing the intake and exhuast ports off, taking the upper manifold off and filling the heads with oven cleaner. Maybe chucking a bottle cleaner in a drill and running it through there? BTW I have an '87 4.9L.

 

Probably the only way to completely remove these deposits would be to remove the intake and hot-tank it. The intake that I have is clean from the injectors down due to the cleaning of gasoline, so I would assume the head ports are fairly clean. The gunk just builds up in the runners due to the fact that only air and pcv/egr vapors are going through there.

 

What exactly is hot tanking, and were would I have to take it to be done?

 

Most machine shops should have them. A radiator shop may also be able to do it.