After fixing lots of little things with my MC1, I now have to face up to the task of fixing her major oil consumption issue. When I bought the car I was told from the previous owner that it consumed around 1l of oil per 1000 miles.. however, after driving to the Hockenheimring and back, I measured its consumption at more like 1l per 300 miles.. not so good eh? The car has done 190,000 miles, and gives a puff blue smoke when approaching the redline.. but will also consistantly burn through oil if I stay under 5k rpm. From outside the car you can really smell the burnt oil even on tickover .
I ran a compression test last night, and to my surprise I found out that cylinders 1-3 were all running at around 195psi (-+5psi) after roughly 4 cranks of the engine. However, cylinder #4 was blowing max 110psi, and was literally coating the end of the compression tester with oil after each run. Well there's the problem. I tried the test again with 2 teaspoons of oil in the cylinder, and she blew 120psi.. however there is SO much oil entering the cylinder anyway, that test probably isn't very useful.
I am very inexperienced with car mechanics like this, so i will need some help trying to figure out what is going on.
So the oil is either entering the cylinder via the valves stem seals or the piston rings right? But with cylinders 1-3 showing such strong compression readings, I find it hard to believe that the rings are going.. unless cylinder #4 has some sort of catastrophic piston ring failure (is that even possible?!). My other theory is that the stem seals have sh*t themselfs on cylinder #4, leaving an oily mess on the valve seat and therefore ruining the seal (and causing my compression and oil consumption issue).
I am tempted to pull the head off, give everything a clean and replace the stem seals.. Should I do this or does anyone have a better idea of whats going on?? Cheers