2.3L ('83-'97) 2.3l burning oil

[frozenrabbit]

94 ranger 2.3l, unknown actual miles.
has been using oil, only has visible smoke some days, if parked overnight on an angle. Just replaced all valve stem seals last week.
Was thinking rings. Ran a compression test, dry numbers were 155, 160, 165, 170. Fresh head earlier this year with proper lapped valves. Pressurized cylinders to replace valve seals, no excessive air leak down.
Isn't the compression numbers in a range for not being worn rings?
No leaks anywhere, block, pan, and below rear main are all clean.
I did have some oil behind the throttle body when changing valve seals, what would cause that?

 

[rusty ol ranger]

Check your PCV valve.

 

[RonD]

+1 ^^^^

Also pull a spark plug or two, from different cylinders, and have a look to see if they show signs of oil burning

And O2 sensors....................they need to be changed every 100k miles or 12 years which ever comes first
Smoke could be Rich mix from old O2s


Oil types
All piston engines have "Blow-by" comes with the territory
When a cylinder fires some of the HOT gases will "blow by" the piston and rings and into the crank case, hence the technical name blow-by, lol

These HOT gases WILL vaporize some of the oil coating the piston, rings and cylinder walls, its the ONLY source for oil VAPOR in an engine, bearings and valve train don't get anywhere near hot enough to vaporize oil

PCV system was added to pull the blow-by gases(exhaust) and oil vapor into the intake to be burned instead of just venting it to the outside air, which is what pre-1960s engines did, lol

As an engine gets older Blow-by will increase, so oil vapor in the engine will increase
So cleaning/replacing PCV Valve needs to be done more often
Generally on newer engines clean/replace PCV valve every 4 or 5 oil changes
Over 200k miles every 3 oil changes
Owners discretion after that

Some add "Catch Cans" on PCV systems even on newer engines
Catch can is put on the vacuum hose between PCV Valve and intake manifold, it promotes oil vapor cooling so it condenses inside the "can" instead of going into the intake, then the can is emptied of oil as needed

Less expensive oil tends to vaporize more, so.......................more oil vapor
Which is why oil Type can matter

 

[frozenrabbit]

Going to look into PCV, don't know how else would put some oil behind the throttle body. Plugs all looked good and clean burning, no oil residue at all.
Smokes only some days, if parked at an angle overnight. Clears up after a few minutes of driving. Some oil soot in exhaust tip, but not soaked. Doesn't seem down on power, doesn't run rough at all.

 

[RonD]

PCV systems have a Breather hose that allows fresh filtered air to be pulled into the valve cover area as the PCV valve pulls out Blow-by/oil vapor

If the blow-by is too much at certain RPMs/engine loads then the Breather flow is reversed and blow-by/oil vapor goes OUT the breather hose and into the air "tube"(from air filter box to upper intake) where it is sucked into the intake(throttle body) and the oil vapor condenses on the colder metal of throttle body
This is NOT unusual, normal operation for PCV system because the blow-by is burn in the engine regardless
The amount of oil vapor coming out the Breather is what would be unusual

Remove Breather hose and check it for oil residue, clean it out