head rebuild question

[bonestock240sx]

91' 240sx 186xxx miles
ka24de/ intake/ 3inch exahust/ gutted cat

My car blows blueish smoke when starting up and when accelerating from a stop. just a puff or two and then its gone.
my compression is pretty even at 150 besides my 2nd cylinder is 145. I know blue smoke is oil. So my question is since the compression is pretty consistant would the rule out my rings being worn out? and that the smoke is coming from worn valve seals? if so, i will be replacing the seals, should i replace anything else im a on a very stringent budget so im not going with ne thing performance. i was thinking about replacing my valves but they add up pretty damn fast. let me know what you think.

thanks

[jak89]

I have the same problem I'm pretty sure its the stem seals. I would just change the seals, I'm just gonna wait till i build the whole motor.

[ReX2SX]

Besides valves seals theres not much else to replace. I mean, you could have the shope maybe check clearances and the condiiton of the guides and seats, maybe even the flatness of the head.

But for now since its just a DD id worry about the straightness and your seals.

[the converted]

Since you're on a budget, I'd just replace the seals and see if that does anything for you. Everything else would require going into the engine to fix, and can get expensive quick.

[bonestock240sx]

ight thanks guys.... i heard that you dont have to take the head off to get the stem seals out... is this true? i heard you can use an air compressor that keeps the valves up and you can pull the stuff out.

[ReX2SX]

Yeah you could.

[the converted]

Air compressor if you have one, or if not you can feed a small rope into the spark plug hole and then turn the engine to hold up the valves up. It might be ghetto, but it worked damn well for me before I had a compressor.

[bonestock240sx]

http://www.frsport.com/Supertech-VS-N7E ... 15388.html

this is what everyone is referring to as stem seals/ valve seals? is that name interchangeable. my dad is saying that its not the seals its the guides... idk much about the head and whats leaking. but im just trying to do this with out having to take my head off so i figure i replace the valve seals using the compressor method and it doesnt fix it then i will have to take the head off, but if it works and it stops the smoking no need to take the head off.......

[bonestock240sx]

i guess im not seeing how i can get to the seals without taking the valves out.... can someone explain this a little better to me?

[ReX2SX]

i guess im not seeing how i can get to the seals without taking the valves out.... can someone explain this a little better to me?

IF you have enough air pressure pushing the valves up. As you for the spring down and remove the keepers you can pull off the from the valves, hoping that if the valve did move it returned to its seated postion. Now the problem you MIGHT run into is pushing the spring down. You can use a regular vave spring compressor...but theres many ways around that, you can hink of something. Also dont take me word for word. This is just w/ the knowledge ive gained from bulding other motors, never a KA though.

Valve guides are different. There could be excessive oil clearence between the guide and seals but im not sure what the effects are.

Just letting you know valve seal and umbrella seals are interchangeable words. Valve guides are completely different

[bonestock240sx]

cus my dad is saying there is no way.... judging from the pictures that we can get to the valve seals. i went to everythingnissan.com and looked at their view of where everything was at and it looks like its at the very bottom of the valve. so he is saying you cant get to that without taking the valves out.

[the converted]

Valve seals are under the springs. Here's a quick step by step to get to them.

Pull cams
Remove shims over valve springs
compress valve springs, remove the keepers, the retainers, and then the valve spring
you'll be left with the valve stem with the seal
grab a pair of pliers and yank of the seals

Hope that helps. It's also not going to be the guides, all they do is guide the valves

[bonestock240sx]

okay... well i just got my spare head cleaned up and rebuilt. so im just gonna install that and take the other one off. my dad wasnt listening to anything i was saying and saying the guides were messed up and stuff and that it wasnt the valve seals. so idk. thanks though!

[ReX2SX]

ask him to check oil clearance of the guides. They CAN contribute to oil consumption.

Just 1 of the MANY LINKS out there..
http://www.aa1car.com/library/ar696.htm