Burning oil, valve seals bad?

[talon1997420a]

okay, well i had a previous thread about rebuilding the motor in my n/t talon, but i'm going to college next year at university of northwestern ohio for high performance/ auto tech and i decided if i could make it last, i'll just use resources there to build a motor for my car. heres the problem. i was told that my valve seals are bad, because the car will sit there and blow blue smoke out the exhaust while its idling but then when you rev it or are driving, it clears out. also, when i drive it it feels like there is no loss of power whatsoever. i did a compression check and it read 195 psi, 193, 204, 200. that sounds pretty good to me if they are all that close and it makes me wonder if the motor in this car has been done before, because for 187000 miles i'd say thats pretty high. my question is, does anybody think it could be anything other than valve seals? and everybody who has built a 420a before, how hard is it to just change the seals if that is what it is? do i need to pull the head?

 

[Griffeclipsed98]

Whats up! I have a 98 n/t 420a. and have had my motor built in the past year, and your compression is right where it should be, and it looks as if you have the typical crank walk issue that pleagues the 420a i'm guessing that your lower compression numbers start on the timing belt side of the motor, its pretty much the same in almost every motor, but this wouldn't cause the smokeing issue becouse your compression is fine if it drops down to 150 160 then yes, but your fine. there is another typical issue with the 420a and its a reall easy fix. and it has to do with the use of a pcv vavle on the intake manifold, they never really work they way they are suposed to work and i dont really know why there is one on there in the first place. in my case i was getting excessive amonts of oil in my intake manifold. you can check by looking past your tb. and also on the backside of the butterfly valve of the tb, to fix this just slap a catch can on your breather line that go's into the intake manifold from your valve cover also remove the breather line that gos into your intake pipe. i just capped mine off.

now your question about replaceing your vavle seals, Yes, you have to remove your head to do this. due to the fact if you remove the valve spring retainers the valve will not matter what slide down into the cylinder. there is a Youtube video call " how to mirror valves on a 420a" its a good example of a way to do it on your own with out the use of a shop valve spring press. check it out, its cool how he does it, i hope that this will help you out

 

[inthecease]

I dont know what else it could be considering your compression is pretty much where it should be but it isnt terribly hard to replace the valve seals and you really dont need to pull your head becuase everything you need to acess is right on top but if you want to take the time and save your back you could pull your head but then you will have to worry about replacing other things like your head gasket which can be a headache and a half especially if you dont do it right the firs time and you will have to replace it again which involves pulling the head again.

 

[KevinRR]

Why don't you do a leak down test to find out what is exactly wrong. Because a compression test will not tell you if the valve seal is bad.

 

[TYGRR]

I'd do a leak test just to be sure. The blue smoke definitely sounds like the seals to me.

 

[talon1997420a]

i've been told by several people that they think its the valve seals and myself also thinks this is what it is but i will do a leakdown test to be sure. and i knew that crankwalk can potentially happen to any engine, but i have never heard of any instances of it happening to a 420a car but maybe i'm wrong? everything i've read about on here has to do with a seven bolt 4g. and all the vacuum lines going from the valve cover are taken care of already. i was given an idea last night on how to change the valve seals without lifting the head by my girlfriends dad, who has hot rodded stuff all of his life and i believe it will work. he said he's done it before working on small block chevy's and what not. it involves just the hose from a compression tester, and you screw that into the spark plug hole and hook it up to an air compressor and it will put air pressure in the cylinder and hold the valve up in place so i can do what i need to do. it sounds like it will work to me so i'll have to give it a shot.

 

[2soon2]

A leakdown test will definately help.

 

[Blak Pearl]

I'm confident to say its your seals for sure, but the leak down test will make things a lot easier and quicker.