Valve Seats or Piston rings?
 

1997 stock except headers, Honda civic hatchback DX. D16Y7 engine.


Car has welded headers and starts and runs fine. Idles great with a small amount of bluish smoke at start up. Today while driving with my coworker (her car) from 50-60mph a huge cloud of blue smoke would come out and it would slightly misfire. Keeping the car at 70-75 no smoke and below 60 was fine until we hit a hill and the same thing happened under load. Got my compression tester and got after 8 consecutive cranks;

180
179
179
180

Car has 131,000 miles on her and she says it's being doing it for the past 2-3k miles when she had a shop last do the water pump and timing belt. On one car I worked on it was the valve seats. Another i worked on it was the piston rings. Adding oil to the cylinders didn't raise the compression more than 6psi.

Re: Valve Seats or Piston rings?
 

General rule of thumb, assuming things like PCV and oil level are ok......

Smoke under high manifold vacuum: valve stem seals.
Smoke under load and higher RPM: Rings. Oil rings stuck.

Compression test cannot evaluate oil control rings. They could be completely missing and still show good compression test numbers.

Re: Valve Seats or Piston rings?
 

Havent checked the pcv valve BUT heres an odd twist. She just texted me saying the engine light came on and all the smoking completely stopped! Said it drives like how it was before smoking but I told her to use the code reader i left her to see what's going on. p1457 code and p1457p showed up on the reader. She told me that the odo shows 62miles since we checked everything earlier and nothing has dropped in level nor has the exhaust fumes started to smell.

Weird one on me. I'll see it tomorrow at work to see if it has indeed stopped smoking.

Re: Valve Seats or Piston rings?
 

P1457 is an EVAP leakage in the canister system, completely unrelated to oil smoke and consumption.


It's DARK out, so how would anyone see smoke from the exhaust if they aren't following behind the car right now?

Re: Valve Seats or Piston rings?
 

She and her boyfriend were driving home from a party. Both in seperate cars. I'll see tomorrow for sure if it's stopped. Earlier this morning it wasn't full light and that smoke came out thick as fog

Re: Valve Seats or Piston rings?
 

Maybe it ran out of oil? It can't smoke if it has no oil. :rolleyes:

A hot catalytic converter can hide a lot of smoke.



I've seen engines with stuck rings that can mosquito fog an entire block on first startup, then abruptly quit smoking once the piston heats up and the rings can seal against the cylinder walls again.

My truck will do it almost on command if I shut it off during the first minute after a cold start.

Re: Valve Seats or Piston rings?
 

Valves.

Re: Valve Seats or Piston rings?
 

Havent had much time to look at the car, shes still driving it sparingly and today I was able to pull the new plugs we put in the car to see what they looked like after 107 miles.

Looks like the tip of the plug has white powder (like they were dipped in flour)

Crown of the plug had a few white specks nothing like the tips.

Electrode is completely clean, no marks whatsoever.


I drove and it definitely does have a lot of smoke still, randomly would go away then come back at various throttle. At one point it was like fog was behind us at throttle, and at another push of the throttle none came out at all.

Told her a mechanic would be able to diagnose better than me.

Re: Valve Seats or Piston rings?
 

Wouldn't have the oil overfilled, would it?
Baffle missing from the PCV breather tube area in the valve cover?
PCV valve broken or stuck open?

Is there a ton of oil sitting in the intake manifold?

Re: Valve Seats or Piston rings?
 

Oil level was the same, right at the top hole of the dip stick.

Baffle in the breather tube area? Thats a new one on me sorry haha

There is oil in the intake manifold looking down the throtte body. I took some pics a while back and it totally escaped my mind until you mentioned it.

Didnt check the PCV valve, she is driving over tomorrow and I can then.


Attachment 90474

Re: Valve Seats or Piston rings?
 

I think you might always have a little bit of oil in an intake, they are not perfectly dry.

The breather tube in the valve cover....if it were a big open hole then oil could be free to enter the tube, and that tube is connected to the air intake snorkel.
There should be some sort of covering inside the valve cover to keep it from getting liquid oil in the tube.



Just flailing in thin air here. You could disconnect PCV and breather tubes for a short test drive to see if smoke quits.




I think it'll be a combination of rings and stem seals

Re: Valve Seats or Piston rings?
 

Smoke stopped with the PCV tubes unplugged.

cleaned out the valve as well, just put it back together and went on a 20min drive.. no smoke!

Re: Valve Seats or Piston rings?
 

I think the 'randomly' is what made me think of PCV. But issues are so rare for me to see.
Rings and stem seals usually follow stricter rules.

At least you're on to something ...hopefully

Re: Valve Seats or Piston rings?
 

PCV: replace every 4th oil change (12,000 miles). Autozone sells an aftermarket for $5

Re: Valve Seats or Piston rings?
 

One month and 1200 miles later I get a call about the car smoking again. So this time I got her to leave the car here for a few days.

Leak down test has 15-18% loss in each cylinder, I can hear air coming out of the rear oil passage in the head behind cylinders 3 and 4. No air seepage through the oil dipstick area, exhaust, throttle body, and no bubbles in the radiator.

As of now the car is mine for a few weeks while she is on vacation. Told me if it's able to be fixed under 1000 then she'll pay me and my boyfriend.

Re: Valve Seats or Piston rings?
 

How much oil is in it?
Too high or too low?
Has the oil level dropped since you last saw it? Has the driver added oil?



IDK.... air filter clogged causing suction on crankcase? Pffft.

Re: Valve Seats or Piston rings?
 

Oil about 1/8 away from the top level, she has done nothing to the car since the last time we looked at it haha.

I hooked up my scanner to it and drove around, nothing popped up as off to me.

Re: Valve Seats or Piston rings?
 

Haven't done much, car still here as they have her boyfriends Mazda to use, here's what I got some daylight to look at it.

Added oil to the cylinder after the guy who sold me my valve stem seals told me to try a old trick;

cylinder compression dry/wet:

1: 180psi/180psi
2: 175psi/210psi
3: 180psi/180psi
4: 180psi/180psi

Looks like I need a ring job on this car, someone stole my old compression tester, had to use some cheapo one that isn't exactly but that cylinder 2 looks like a problem.

Re: Valve Seats or Piston rings?
 

How much oil did you get in there? The 3 that didn't change at all should have changed SOME amount if you got enough oil in them.

If #2 was the sole culprit, that spark plug would probably show more evidence of oil burning than the other three.

Re: Valve Seats or Piston rings?
 

Shows more white residue. Yeah this cheapo harbor freight tester isn't that great but tested them all twice and the same readings at 10 cranks