A while ago I bought a UK vvt motor. When I took the valve cover off it looked fine. 6,000 miles later I'm in the process of changing timing belt etc. I notice the rearmost part of the head is dirty and has a layer of sludge on it. 3k oil changes and the oil was dirty but not disgusting. I do have a catch can with lines running from the pcv hole, 1/2'' (no valve) and from the hot side, 3/8''. Both are vented to air via moroso catch can with dual outlets. Could my catch can setup be causing a sludge buildup? MK turbo, so oil cooled only, and running about 11 lbs. of boost. Is there anything I can do to get rid of sludge? I'm using Rotella T-6 now.

 

By “sludge” I assume you mean oil/dirt/grime? Having removed the valve cover 6k miles ago leads me to suspect that the VC gasket folded over on you, seeped oil down the back and driving on dirty/dusty roads. Been there, done that before, particularly using a thick gasket and was trying to put the VC back on in a hurry at the dyno. Another possible culprit is the corners on the CAS If it’s not the seal. Can you see/find a trail? Clean it off good, watch it closely and you’ll find it.

 

I had put a new gasket in before. The sludge is confined to the rear of the head, on the intake side. It's a kinda black tarry coating right in the corner. Will I wash my bearings if I use some kind of motor flush, or should I just do more frequent oil changes. I know Rotella is supposed to have heavy detergents and I'm perplexed how so much crud accumulated in such a short time.

 

I’m fairly certain OP is talking about sludge buildup on the head, beneath the valve cover; not on the exterior of the engine.

 

Sorry if I added confusion.....now wrapping my head around why and how sludge built up inside the head, just like OP.