(Another) oil consumption problem

[Whaler]

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 

[KiNK43]

Well if the rings or stem seals are gone the head will need to come off anyway so may aswell just go for it. But you can remove exhaust manifold for example and see if the exhaust valves are wet.

[KiNK43]

Seems to me like youve got a bad piston ring Or maybe a damaged valve. No expert myself  but the low compression would not solely come from a bad stem seal.

[Whaler]

I pulled off the head last weekend and took everything apart for a good clean. I lapped all the valves, replaced the valve seals, changed the headgasket etc etc. Compression is now up to 190psi on all 4 cylinders (not bad for a 190,000 mile motor). I will monitor oil consumption over the next few weeks, but the early signs are looking good   

[dr_broon]

Fingers crossed mate

[Whaler]

Right so I have been monitoring the oil level for the last 500 miles after the head rebuild.. and its not good news. She's still consuming about 1 litre of oil every 300 miles. This is all very confusing as its got near factory compression on all 4 cylinders, new valve seals, new head gasket etc etc. Also the car doesn't appear to be smoking, I can take it up to 6000rpm with practically no blue smoke in the rear view.

 

After some research, I found it could maybe be a broken/stuck open PCV valve?? but Im not sure if that could be responsible for such a large loss of oil? I guess if its loosing a small amount of oil constantly then it could all add up, plus that would explain why Im not really seeing blue smoke.

 

If swapping the PCV valve doesn't work then I guess it must be the rings.. maybe the oil control rings are shot but the compression rings are still good. (in which case it would probably be bye-bye aerodeck )

 

sooo does anyone have a part number for the PCV valve for our civics (d16)?? I can't find anything online

 

Also if anyone has any other ideas then let me know!! Cheers