Smokey 200TDI???

Hi.

After selling my last 90 a couple of months ago I decided to get another for a bit of offroading.

Last week picked up a 182k 1985 90 with a disco 200tdi transplant.

On the way home I thought it seemed slow, both acceleration and top end but put this down to forgetting what they were like!!

Got home and found oil all over the rocker cover and engine casings. Seemed to be coming from rocker cover so I nipped up the 3 bolts. Tested and still small amount of oil from the oil filler cap.

Today I replaced the oil filler cap and drove down the road followed by a constant cloud of light blue smoke!!! Went back home and lifted the bonnet. No oil leaking from oil filler but lots of blue smoke and oil dripping from joints in the exhaust.

I have checked the breathers and none appear blocked. It seems the engine was breathing through the oil filler cap. Now that is air tight it's putting the oil out of the exhaust.

Where do I start with this?? I suspect piston rings but I'd happily be proved wrong!! Any suggestions gratefully received. Believe engine has done approx 160k.

Could be headgasket. exhaust gas into the oilways then escaping through defective cap, fixed cap now oil forced down exhaust pipe+burning in the hot exhaust manifold, am i wrong is saying early for rings? else its been well abused.
did you not look over engine b4 u bought it? sorry dont mean to sound like an arse, sorry if i do, but after a short test drive surely you'd seen all the oil. hope you paid little for it? new engine