ghostly240

Hi, I have a 1992 240sx with a ka24de that I just recently purchased. now this a tough boy because its read 247,xxx on the odo. I have no idea if it's the original engine.

Well, everytime I come out of 1st at a light or stop,when ever i rev it, and when im in reverse, it likes to blow blue smoke. It's pretty noticeable. It doesn't blow smoke when I idle or anything. And some days, it just won't blow smoke at all. The car doesn't have overheating issues at all.

I've replaced the spark plugs, wires, and did an oil change with 5w-30 high mileage syn blend. There's no signs of coolant in the oil or oil in the coolant.
I recently did a compression test at school and got:
1 - 190
2 - 185
3 - 195
4 - 190

So that basically tells me the hg isn't bad, which im curious about since it has so many miles on it. The car does kind of like "pop". not a misfire, or any backfire. doesn't sound like an sti. but like a little pff from the exhaust, especially if i hold it at 2k you can hear it.

When i bought it, the dude said he only drove it here and there because it was going to be project car but he never got around to it. it has a straight pipe welded megan racing exhaust if that has anything to do with it.

I read a lot of threads and stuff about ka's blowing blue smoke and the only thing I think it could be is the valve guides. If it is, should I just replace them or just buy a new head?

snowsurfdirtx

Mine does the saaame thing. Haven't done a comp test on it. Curious to see what the issue is. Just picked mine up a few days ago.

Sent from my SAMSUNG-SM-N910A using Tapatalk

RoastedBumper

Try doing the compression test after pouring a little oil in the cylinders and look at the difference. Could be your piston rings

__________________

silviamang

Valve guides probably would not have to be changed unless there was some kind of damage to the head or if you are rebuilding it.
I am guessing some valve stem seals would be your answer. Does the car blow this blueish smoke when you first cold start it?

ghostly240

Ehh, not really. It will just blow white smoke because of condensation but that goes away after warming up. But the blue smoke doesn't really start until driving around for a little bit. Really noticable at night in peoples head lights. The amount of smoke varys all the time.

Could a thicker weight of oil help a little until i can get to fix it or no?

snowsurfdirtx

Mine does a little bit. Gonna run 10w30 and see if that helps.

Sent from my SAMSUNG-SM-N910A using Tapatalk

RickBlaine

Valve stem seals, piston rings, and/or even the PCV valve. A clogged PCV valve will cause some oil burning. There are good write-ups on how to change it, though its location is not the best.

A thicker weight oil will help- but it will be masking a symptom- not curing the disease.

Those are good compression numbers but still, add a squirt of oil in each cylinder one at a time and check the numbers again- just to rule out piston rings.

Remember that an engine is essentially an air pump- any clogging of the breathing means that the engine will pull in oil, not air. Just make sure the previous owner did not do some weird things with the intake or breather tubes.

Report back please....

snowsurfdirtx

Thanks. I'll check the pcv and report back. In my case I just need it to last til spring in which case it'll have a new ls3 heart transplant.

Sent from my SAMSUNG-SM-N910A using Tapatalk

ghostly240

Alright, I can probably do it at school this week, I'll be sure to write back