Help - I'm Burning Oil!

I purchased my 1999 Forester with 62,000 miles about 30 days ago. It has a manual transmission and the 2.5L engine. I've driven it about 4000 miles and the engine has used 10 quarts of oil! That's 400 miles per quart of oil!

Compression test shows all cylinders about the same, 155 to 170 psi range Reving the engine above 4000 rpm, yeilds dark black smoke out the exhaust pipe. There are no external leaks from the engine or transmission area. There is no smoke in the exhaust at start up. Spark plugs may have a slightly brown dark ash, but the engine is running fine with no misfires or fouling of plugs. The well for Spark plug #1 was full of oil when I pulled the plugs.

I think the valve seals are leaking, but is there something else I may be overlooking? How difficult is replacing valve seals? Will I need to pull the camshafts or just the rocker assembly?

Thanks for all your help! Pete

Reply to
Peter Styer
Loading thread data ...

You may very well have some bad seals BUT ,if you want a shot at slowing the leakage, clean or replace the PCV valve (and maybe the tubing as well).

Carl

1 Lucky Texan

Peter Styer wrote:

Reply to
Carl 1 Lucky Texan

Reply to
Edward Hayes

Bad valve seals will cause smoking at idle, when the vaccuum in the engine is highest, pulling oil past the seals and burning. To check, let the engine idle when warm for a few minutes, then accelerate the engine a little. Bad seals will show up as smoke in the exhaust. If no smoke, oil must be leaking from somewhere that may not be obvious. Seals can be changed in place, but it's not a very DIY job. Ed B.

Reply to
ed

Dark black smoke from the exhaust means too rich fuel ratio. If it was grey/blue smoke THIS would mean burning oil. Are you sure about the colour of the smoke from the exhaust? Generally if the valve stem seals are leaking you will see the blue/grey smoke after idling at stop lights for a while. Are you sure there is no leak from the motor somewhere dripping to the ground?

Reply to
Lance B

Sorry - I forgot to mention that I replaced the PCV valve after driving about 3000 miles. The old one appeared to be working. The plunger inside the valve slid back and forth just like the new valve. Peter

Reply to
Peter Styer

It's definitly black oily smoke.

There are no external leaks. The engine was cleaned by the dealer and is spotless underneath. In fact, in thirty years of working on engines, this is the cleanest engine I've ever owned.

Peter

Reply to
Peter Styer

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.