Smoke from exhaust!?

[Lonewulf]

So I just bought my first 240sx about 4 days ago. It?s a 1995 S14 coupe. When I bought it. It had a tick from the timing chain which is getting a new timing kit soon. It ran and drove but it was sluggish and sputtered and also had a leaking i injector. I just went ahead and replaced all of the injectors along with a new fuel filter and that solved my sputtering problem. It is kinda low on oil and the oil in there is dirty, I plan on doing a oil change later today. Anyways yesterday when I went to start it, it started right up no problem and the sputter went away but I noticed as I revved it, it had some grey or white smoke coming out the exhaust and a decent amount of it. As I let off and let it idle and slowed down a ton and was just a tiny bit of smoke. I?m thinking it?s not the head gasket cause if it were it would be pouring out smoke even at idle right? Let me know if you have any advice or if you have had the same problem and how you solved it! Thanks!

[S14rebuild]

Change the oil to start....

What motor and how many miles are in the car?

More then likely valve stem seals are bad and possiably bad piston rings(washed out) due to leaky injector.

Have u compression tested the motor?

[Lonewulf]

It?s a KA24DE with 156k on it. I?m waiting for a buddy on mine to get back from vacation to use his compression tester. I?m also trying to find the best oil to run in it. I read some guy had the same problem and it did turn out to be the valve guide seals

[NukeKS14]

I?m thinking it?s not the head gasket cause if it were it would be pouring out smoke even at idle right? Let me know if you have any advice or if you have had the same problem and how you solved it! Thanks!

Not necessarily. head gaskets can give at different points. between coolant and oil passages, between coolant and combustion chamber. blown headgaskets have a few symptoms, not always smoke.

I second the compression check. here's the FSM on what to expect. If you get low numbers and put a little oil and get better numbers that tells you it's rings/ringlands.. if you get low numbers and oil does not improve them then it's probably valvetrain related, but could also point to headgasket (especially if it's blowing bubbles in your puke tank. check there at idle, that's a dead giveaway for a blown HG, high non-condensible gas content in the coolant.)

Cylinder washdown sounds probable if you truly have a leaky injector. Especially if your compression is markedly lower on that cylinder.

https://www.nicoclub.com/nissan-service-manuals

download an FSM for yourself.

https://i.ibb.co/ThSBtpm/em9.png (https://ibb.co/kcfgXkQ)

The fix depends on what the problem turns out to be.

Might also buy a valve cover gasket set and pull the upper timing chain guides while you're at it. They can disintegrate and clog the oil pickup tube. There are a number of threads on that topic, just do a quick google search. One of the Nico links has a ton of pics.


'best' oil depends on your climate. I run Amsoil Premium Protection 10w40 (https://www.amsoil.com/p/premium-protection-10w-40-synthetic-motor-oil-amo/?code=AMOQT-EA#pills-home_0) on my KA-T. It has a high zinc content which is good for our cam-on-bucket heads. There are quite a few good oils with zinc. the FSM shows recommended oil weights for climate. I run a touch thicker from the added heat my turbo throws in there.