I also say leakdown test. If it hadn't been for that particular test, I'd have been totally lost in finding the dead cylinders in my m110. Mine was rebuilt when the frame had 221k miles on it because it was burning excessive oil.

I did clearance checks once i had torn it down. The skirt to wall was way over spec by about 400%. The valve stem seals were hardened and leaking. The valve guides were just slightly over. Some valves were also out of spec and had to be replaced.

80k km isn't a lot of miles for an engine like that. I'd say you should check for oil consumption. I'd doubt its rings at so many miles. When researching my own, I had found that many people did the valve stem seals more frequently than anything else.

It can be done with the head on the car, but if you're going to do anything to the head, I'd just go the full nine yards. stem seals, valves as needed, guides all around, reangle the valves and valve ports, and check the block and head mating surfaces. That'll get you holding pressure again.

-Troy

__________________
- - - '77 federal 280e - 222k miles
- - - '85 380se - 129k miles
- - - '07 Chevy truck
- - - '79 Datsun 280zx with '82 turbo motor
- - - Currently looking for a clean 190e with less than 160k miles.