Ditto on the good info.
I've temporarily plugged up the three vent slots on the valve cover and added the new vented oil cap. Took it out for a 30 mile round trip.
There was no milky sludge afterwards so I'm pretty confident it's definitely condensation.
This 216 does have blowby and that no doubt is contributing.
I'm hopeful that routing all the blowby and any heat generated in the valve cover out the one single outlet will help retain more heat & help clean it out. And in the process minimize the buildup at the highest point in the engine. I thought it unusual that the buildup was around the front of the valve cover around the filler hole.
I haven't ruled out going w/a 180 thermo but this engine had a 160 in it and I'm pretty sure thats what has been run in it since new.... I'm the 2nd owner and knew the original owner.
I'll be monitoring and will update also.
Dave
