I picked up this 2009 f150 with the V8 3v engine, I opened the valve cover to replace the VVT solenoid then I saw this sludge.

I Am trying to do anything I can before having to replace the engine, considering a diesel flush.

Anyone tried that and what's your thoughts on it?

 

that looks pretty bad. But, don’t think you have a lot to lose by trying to get it cleaned up. I wouldn’t put the new vct in until after you do whatever flushing you are going to do.