Car engine issues

[Espada]

I have a Mitsubishi lancer 1998 with 270000km on it i had the engine rebuilt and almost replaced all of its parts in the process at 250000, now after 20000km and almost 1 year my engine is burning oil like 250 to 500ml each 1000km of distance, the smoke rarely comes out like when i am driving fast and come to slow down then speed again it would give out some smoke and that's it no more smoke or if i am idling and then moving it would give a burst of smoke abit white to grey not black, its driving me nuts as the engine has full power I don't feel any loss of power i can use my AC and travel at 120 to 150km per hour with no issues, i tested the car by standing behind it and making my friend push the pedal to the floor and it give out a small amount of smoke when that's done but ofc that's insane rpm i would never do while driving, my mechanic said its either valve stem or valve guide anyways its now piston rings, my question is this " is it worth it to dismantle the cylinder head and check the valves ? " As if that engine has any issues related to piston rings i will burn it and get another one so could valves really make the car smoke either than early in the morning?

Sorry if my English isn't sufficient enough as its my 2nd language ...…

 

[Espada]

Engine oil: 20w50 API SJ changed every 2000km or 20w50 API SL changed at 4000km full mineral oil

 

[ctechbob]

Classic signs of worn valve stem seals. The reason it smokes when you are coasting down and get back on the gas is that when the throttle plate is shut there is high vacuum in the intake, which tends to pull oil down through the seals. Then you hop on the throttle again and the oil burns off. You might just start with replacing the valve seals, which shouldn't require a complete teardown.

 

[Espada]

Originally Posted by ctechbob
Classic signs of worn valve stem seals. The reason it smokes when you are coasting down and get back on the gas is that when the throttle plate is shut there is high vacuum in the intake, which tends to pull oil down through the seals. Then you hop on the throttle again and the oil burns off. You might just start with replacing the valve seals, which shouldn't require a complete teardown.

So valve stem could cause the car to smoke while running i guess my mechanic has a point and i will remove the cylinder head and pray to god it just stems

 

[ctechbob]

You'd want to check the play in the valve guides while you're in there. If you put new seals on worn guides it will just wear out the seals quickly again and you're back to square one.

 

[Espada]

Originally Posted by ctechbob
You'd want to check the play in the valve guides while you're in there. If you put new seals on worn guides it will just wear out the seals quickly again and you're back to square one.

Okay will do so a valve total check will be done

 

[Mad_Hatter]

Originally Posted by ctechbob
Classic signs of worn valve stem seals. The reason it smokes when you are coasting down and get back on the gas is that when the throttle plate is shut there is high vacuum in the intake, which tends to pull oil down through the seals. Then you hop on the throttle again and the oil burns off. You might just start with replacing the valve seals, which shouldn't require a complete teardown.

+1.. checking the guides as well is also 👠it's a good bet there's play.

You should look at the valve seats as well. Worn valve seats change the valvetrain geometry and can create wear on the valve and valve stem. If they're replaceable (not integral to the casting), you might consider that while you're in there. If I'm not mistaken, I believe aluminum heads use inserts.

 

[DGXR]

Yes it's the valve guides and/or valve stem seals.
If it was the piston rings, it would be smoking exhaust nearly all the time and you probably would not have full power.

 

[Pelican]

Espada, there is one thing that you ought to do due to the area you live in and that is change the air intake filter 4 times as often as recommended.

You'd be very surprised to the amount and where sand can get in an engine in or near a desert.

 

[Espada]

Originally Posted by Pelican
Espada, there is one thing that you ought to do due to the area you live in and that is change the air intake filter 4 times as often as recommended.

You'd be very surprised to the amount and where sand can get in an engine in or near a desert.

yeah its very sandy in here so i do oil filters like every 5000km maximum 10000km

 

[Espada]

Originally Posted by DGXR
Yes it's the valve guides and/or valve stem seals.
If it was the piston rings, it would be smoking exhaust nearly all the time and you probably would not have full power.

mechanic did a check today and informed me that its not stem or either guides and piston or piston rings :/, gonna kill that engine and get a new short block which is better

 

[Mad_Hatter]

Originally Posted by Espada
Originally Posted by DGXR
Yes it's the valve guides and/or valve stem seals.
If it was the piston rings, it would be smoking exhaust nearly all the time and you probably would not have full power.

mechanic did a check today and informed me that its not stem or either guides and piston or piston rings :/, gonna kill that engine and get a new short block which is better

What test did he do, compression?

What did he say how oil is entering the combustion chamber?...Did he look at the valve seats?...there's only so many ways for oil to enter the combustion chamber.

Are you getting excessive oil through your PCV system? If so, install a catch can.

 

[Espada]

Originally Posted by Mad_Hatter
Originally Posted by Espada
Originally Posted by DGXR
Yes it's the valve guides and/or valve stem seals.
If it was the piston rings, it would be smoking exhaust nearly all the time and you probably would not have full power.

mechanic did a check today and informed me that its not stem or either guides and piston or piston rings :/, gonna kill that engine and get a new short block which is better

What test did he do, compression?

What did he say how oil is entering the combustion chamber?...Did he look at the valve seats?...there's only so many ways for oil to enter the combustion chamber.

Are you getting excessive oil through your PCV system? If so, install a catch can.

he started the car when it was already warm and pushed the gas pedal a few times to a high RPM and it smoked a little he told me to keep it running idle for abit of time then he opened the cover of the engine '' where you pour oil into '' and placed a piece of cartoon over it then closed it and increased RPM much higher on intervals and it smoked under load he told me '' it can't be stem seals as the car gets heated metals expand and should not smoke under pressure and because it does its either valve guides or piston rings or both anyhow you need to do both of them together '' so the cost is like 4000 EGP while a new short block would cost about 4500 EGP to 5000 EGP so i came to think i would use an oil treatment to stop the smoke and prolong the life of engine and using a shorter spark plug so it doesn't get fouled easily till i can change the engine

 

[Anduril]

Originally Posted by ctechbob
Classic signs of worn valve stem seals

I figured as soon as he said Mitsubishi

 

[Mad_Hatter]

Originally Posted by Espada
Originally Posted by Mad_Hatter
Originally Posted by Espada
Originally Posted by DGXR
Yes it's the valve guides and/or valve stem seals.
If it was the piston rings, it would be smoking exhaust nearly all the time and you probably would not have full power.

mechanic did a check today and informed me that its not stem or either guides and piston or piston rings :/, gonna kill that engine and get a new short block which is better

What test did he do, compression?

What did he say how oil is entering the combustion chamber?...Did he look at the valve seats?...there's only so many ways for oil to enter the combustion chamber.

Are you getting excessive oil through your PCV system? If so, install a catch can.

he started the car when it was already warm and pushed the gas pedal a few times to a high RPM and it smoked a little he told me to keep it running idle for abit of time then he opened the cover of the engine '' where you pour oil into '' and placed a piece of cartoon over it then closed it and increased RPM much higher on intervals and it smoked under load he told me '' it can't be stem seals as the car gets heated metals expand and should not smoke under pressure and because it does its either valve guides or piston rings or both anyhow you need to do both of them together '' so the cost is like 4000 EGP while a new short block would cost about 4500 EGP to 5000 EGP so i came to think i would use an oil treatment to stop the smoke and prolong the life of engine and using a shorter spark plug so it doesn't get fouled easily till i can change the engine

So it DID smoke at open throttle...ok, that changes things. I thought you had the engine rebuilt?

 

[Espada]

So it DID smoke at open throttle...ok, that changes things. I thought you had the engine rebuilt?[/quote]
Yes i did but it seems like it was a bad job done

anyhow the mechanic said he can't just change valve guides without doing the piston rings is this true ?

 

[Mad_Hatter]

Originally Posted by Espada

Yes i did but it seems like it was a bad job done

anyhow the mechanic said he can't just change valve guides without doing the piston rings is this true ?

No, it's not true. The valve guides are in the cylinder HEAD. You don't need to touch anything in the cylinder to replace worn valve guides. Maybe he was saying that if you're going to replace the guides you might consider also replacing the rings?? I'm surprised the rebuild didn't replace the guides. On old cars the carbon build up on the valve stems wears on the guides and creates clearance or can even "pull" or drag the guide down from it's inserted position.

Maybe they didn't do it because at the time there was no play??