My 91' Civic Si with 157k miles is buring a lot of oil. The oil is seeping in through the spark plug tubes. But i was thinking that isnt enough to slip through the threads. Does this mean i have bad valve stem seals? It seams like they are just went all at once. Cus i am buring a LOT of oil and its causing a misfire once the car is warm. Can you guys point me in the right direction here? Thanks.

 

sounds to me like you have 2 problems that are not related to each other at this point.
first, the leak from the spark plug tubes will cause a misfire once enough gets in.

second, i think either your valve stem seals or your piston rings are leaking if your burning oil.. i serious doubt oil from the spark plug tube will fall into the cylinders if the plugs were torqued correctly. also, you could have multiple leaks also, rear main seal, cam seals, crank seal, valve cover seal, distributor "O" ring seal, etc.. but i would start from the top and work your way down. replace your valver cover and spark plug tube seals first.. clean the engine and check under the hood every once in a while to see if u can locate any other external leaks..

but if your getting that burning oil smell from your exhaust, i would do a leak down test to make sure its not your piston rings. then go from there..

 

Thanks. Well i know the engine leaks externaly, that doesnt concern me much. And i am confident it isnt the rings because the oil burn increases the longer i drive the car. If it were the rings, i would think it would be worse on start up.

But i took auto a long time ago and i remember the leak down test. But i forgot how to perform it?

 

like a compression test.. pull the connectors off the injectors, put the compression tester to which ever sparkplug cylinder whole u wanna start with, turn the key and let the motor turn for about 8 turns. check the guage and write down what u see.
then unhook that and drop about 2 to 4 drops of motor oil into that same cylinder u just check and hook the guage back up. turn motor again for about 8 spins and check the guage again
if the guage reads the same as the first, then u know your piston rings are good in working condition
this test just eliminates the piston ring damage. but if your complaint is about burning oil, and the rings test out ok, then id go ahead and do those valve stem seals.

good luck, if i forgot something, im sure somebody will correct me.

 

That's not the correct method of performing a leakdown test. You will need to warm the engine to operating temp, remove the sparkplug from the cylinder, screw in the tester hose, and set the cylinder to TDC. Next hook up the leakdown tester according to its instructions. Make sure you have a compressed air source above 100psi, otherwise it probably won't be accurate.

Obviously the higher the % of leakage, the worse, but you need to figure out where it is leaking. This is why leakdown tests are much more accurate than a compression test. If you hear air leaking out of the crankcase through the oil cap, than its the rings. If you hear air leaking out of the intake, its the intake valves, if you hear air leaking out of the exhaust its the exhaust valves.


To the Op, you have a couple of things at play here. You need to stop the oil from leaking into the spark plug tubes. Replace the spark plug tube seals underneath the valve cover first, then replace the rocker tube seals if it is still leaking. If it leaking enough oil into the tubes, it most definitely can cause a missfire. Generally when valve stem seals leak, they will only smoke at start-up and then stop. When rings are going out, generally the car will smoke the entire time the engine is running. Leaking valve stem seals will not show up on a leakdown test because they are not within the combustion chamber. If you believe that they are leaking, then remove the intake or exhaust manifolds and visually inspect the valve stems, it will be obvious if they are leaking.

 

block test it see if your head gasket is good. I't might cause a misefire once engine is fully warm. If your leaking oil into the actual spark plug holes im thinking its your gaskets on the cover that are leting oil in if thats the case oil can foul your spark plug wires and cause a misefire also.
Also if your rings where that bad youd see blue smoke out the back the whole time the car is running the worst the ring are the more smoke youll see thats once engine has reached operating temp.