I just change the valve stem seals in my 94 mazda mx3 1.6L. i did it right like i know w/c are the exhaust valve stem seals and the intake valve stem seals. i also grind the valve seats for better compression. now it still smoking every morning and im guessing oil is still going in the cambers when left overnight. It runs good and more power before i did the overhaul, its just the oil still going in the cambers, and 1 thing i noticed when i did the valve seals is that i drop a small thin washer but didnt know what it was and where it was from, i check everything before i put everything back but didnt know what it was for. couldnt be that im missing something? or did something wrong, i mean i did a lot of engine overhauling from import to domestic cars and truck. and this is my first mistake ever. pls help thank you

Valve clearances are the small gaps between the tops of the valve stems and the part of the mechanism which presses on them to open the valves . Check the clearances at regular intervals as specified in the car service schedule, and adjust if necessary. Reset the clearances whenever the cylinder head has been removed.
https://www.howacarworks.com/engine/checking-and-adjusting-valves
Incorrect clearances can cause the engine's intake and exhaust valves to fail prematurely, which can lead to engine idle and drivability problems, as well as excess pollution. ... If the valves are too tight, the vehicle may also exhibit rough running characteristics either cold, hot or all the time.
https://www.quora.com/Why-happens-when-the-valve-clearance-is-high

Do you only buy one shoe if it is worn? replace all of them, unless you want to cheep changing them one at a time.

burn oil bad rings or bad valve guides. if it using a lot of oil. or it can be the intake valves stem seals asn oil is mixing with th fuel. same on exhaust stem seals but its uses more dusty black as its not being burnt just pushed into the exhaust. these all can give black smoke. you can tell alot more from what colour your spark plugs are. and a compression test will identify if its a gasket or the rings or valves. do dry test then do a wet test with 3 drops of oil. and if the compression has gone up more than 1 psi you have a problem. also check the oil filler if you pump air into the piston and you can hear it a lot coming out of the oil filler its the rings gone. if you hear it out of the air intake its the intake valve side and if out the exhaust its the exhaust valves. all these is best to be done before you decide to take the engine apart to look for the problem as this will identify the problem., ecotec engine can also be the hydraulic valves blocked so if this engine is installed check them as leaves valves open to long. and can be loud tapping and also a ting sound. usually means they are blocked and oil change is also need. as they are feed from the engine oil.

Hey Anon..this is a serious problem ONLY if you do not keep your engine oil level full...but you do need to get it repaired as soon as you can..
Sounds like you may only need new valve stem seals...BUT.. you need to check and see if your car smokes when driving.. especially when you are stopped at a red light, then take off again...Does it smoke then.>??? >> THIS IS IMPORTANT!!... It determines whether its rings and/or valve stem seals.. If it smokes after a red light.. it could be rings and valve stem seals.. If it ONLY smokes in the morning.. its a 99% chance its just worn out valve stems seals...
Find a qualified professional (ASE Certified or Toyota Factory shop) ..This is NOT an inexpensive fix..BUT - ASK if they will replace the valve stems seals without removing the heads..( I KNOW they can..its just a matter of WILL they!?!?)...BUT....The shop will want to rework your head(s).. called a "valve job" and this is normal,-- they will remove the head(s), all the valves, regrind their sealing surface and regrind the valve seats in the heads, install new valve stem seals, new intake gaskets, new head gaskets, fresh antifreeze..(get a new -QUALITY- thermostat and have them install it - no need to chance overheating your engine), they should "surface the heads".. giving them a fresh gasket sealing surface.. this will restore the sealing surfaces and help with the compression, and I would recommend letting them do it if you can!!....if you do this -- MAKE SURE you ask/demand for ALL your old parts back,-- all of them!! Good luck,, please mark as/if helpful...thanks!!

Hello,
There is a service bulletin out for this code. Error Code P0300 indicates a need to replace the exhaust valve springs and seals. This mean the head has to come off and the proper repair performed. Your probably getting a little knocking at this point. If your truck should be under warranty have the dealership repair this. Parts to include

1. 2596078 - Spring Exhaust Valve x 10
2. 2596501 - Seal Exhaust Valve Stem x 10
3. 24100165 - Gasket Throttle Body x 1
4. 12565425 - Bolt, Camshaft x 1
5. 24100263 - Bolt, Camshaft Position Actuator x 1
6. 12586690 - Gasket Kit, Intake Manifold x 1

Regards, Tony

YES if you don't have the right tools
or the know how.
may want to take this one to a good shop.

Try this if you have rge 323 BG

Valve clearance - inlet: 0.30 c mm (cold)
Valve clearance - exhaust: 0.30 c mm (cold)

sounds like u haven't regularly serviced the car ! If there is oil coming out of exhaust it will most properly be a fouled spark plug or plugs but the reason 4 it fouling plugs would be either leaking valve stem seals or piston rings!!!
Change spark plugs and see if problem rectifies!

White smoke is usually oil...sounds like the engine is burning oil thru the pcv system. Somehow oil is getting sucked backed down the intake and getting used again. Try changing the pcv valve on top or near the valve cover. It usually has a tube going to the carb base. Remember, all engines draw air in like a vacuum.....find your oil leak, and you will cure your smoke prob. Good luck.

You either have had the wrong valve seals installed, they are physically missing, or the valves are incorrect (too loose in the guides/stem too thin). The rocker arm seals will not contribute to your issue. If it did not have the oil smoke before you took the head off, the issue is with whatever the machine shop did. Valve seals have to fit TIGHT, or oil will go down the valve stem into the intake.
Take the head back to the machine shop & tell them to fix it. For free.