How common is it for valves to leak oil into the cyclinder?

we always assume piston rings first, but what causes the valves to start leaking oil and is it more easily prevented than ring damageHow common is it for valves to leak oil into the cyclinder?
Depends on how old and how many miles auto has on it. The valves don't leak its the valve stem seals that leak.There are some oil additives that can help the problem for awhile but you will eventually have to replace.Which can be done without pulling the heads off.But to answer your question as to what causes them to leak is not changing the oil often enough and some types of oil are not as good as others and high miles. Hope this helps you. Good luck.How common is it for valves to leak oil into the cyclinder?
I DO AGREE WITH THE ANSWER GIVEN. IN ADDITION TO THAT, ONE SIGN OF VALVE SEAL FAILURE IS WHITE SMOKE WHEN U FIRST START THE ENGINE JUST FOR FEW SECONDS. Report Abuse

THIS HAPPNED RECENTLY WITH MY 1.8L JETTA CAR. I ALREADY REPLACED THE SEALS AND THE WHITE SMOKE NO MORE. Report Abuse

My Chevelle did this for a while and same with my truck both with Chevy 350, the number 8 cylinder would always leak a drop of oil when the engine cooled, then when starting it id get a small puff of blue smoke and it would clear out and run fine, to fix this add air pressure to the cylinder with both valves closed to hold them in place and then use valve spring compressor to take out the keepers and remove the spring and then replace the valve guide seal and put it back together. number 8 cylinder is under oil most of the time in the Chevy 350.
NO it is not suppose to leak.





What makes you think there's oil leak? If you have leaking fuel injectors the spark plug would look wet (like oil) too.





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The valve SEAL leaks as they get older. Some motor oils (high mileage oil) have additive to swell up the valve seals.








Good Luck...
You didn't say anything about mileage on the motor. A high mileage motor can have the valve stems wear away enough for oil to leak past them into the cylinders. Rings will not be far behind.
could be as simple as a valve cover gasket leaking oil down the spark plug tubes, more likely than leaking from the valves themselves.
valve stem seals would be a bigger problem. prevention is not so easy. a head job and routine maintenance.
the seal and not so common really nothing to do





thanks down there couldnt think of it