Chrysler Repair: Why blue smoke from exhaust?, dodge spirit, piston ring

Question
I just bought a 93 dodge spirit for her , when you give it gas to go. it blows out blue smoke . what would cause this ? some one told me , the rings would ! but to tell you i have no clue.

 Thanks for your time

Answer
Hi Don,
Blue smoke is a sign of oil in the combustion chamber being burned at the time of detonation. It comes from either leakage around the 6 piston ring/cylinder wall interfaces or from excess space between the valve stem and valve guide into which they fit (12 such interfaces in a 6 cyl engine). The 3.0L V-6 engine which may be in her Spirit has a track record of the valve stems being the source of oil burning. There was an improvement made in the early 90's that was supposed to improve this so it is a bit unusual to have it in a '93. You can distinguish valve stems from rings by doing a leak down test of the compression with or without a teaspoon of oil added thru the spark plug holes (one cylinder at a time). If the compression improves with oil added significantly then the problem is the rings.
Another symptom of the valve guide is that after the engine has cooled down from an earlier drive, the initial cold start will produce copious amount of smoke whereas that is less likely if the rings are the cause.
The valve guides can be replaced without removing the cylinder heads which makes it a less costly fix than were it the rings. With either cause the symptom that you describe ("when you give it gas to go") will occur because whenever you decelerate there is a temporary increase in vacuum within the combution chambers which sucks oil in around worn rings and guides with equal facility. So notice the first start in the morning as a more reliable determinant of the specific cause. You may have to weigh the oil consumption costs (pollution, oil costs) against the cost of the valve guide replacement and also consider the mileage that she puts on the car each month and how far she might drive it before you sell it in deciding whether to invest in the repair.
Roland