Sulaco

As title says. 180k miles, pulley and headers and tune and all that. Car has had the same mods since about 100k miles. I've had it 50k miles.

Today on a road trip I noticed consistent smoke out the back for about 5 seconds and only after a wide open throttle pull. Car runs fine, everything else is golden, no codes.

Valve seals? Early sign of ringland failure?

Sulaco

bump. Something in the PCV/Vacuum system? Valve seats or stem seals? Spooky piston rings? I've also only noticed it does it after WOT pulls above 70mph. Never does it below interstate speeds.

drothgeb

I have a motor down because rings/ring lands on cyl 8 (granted, it was a high comp motor I beat the **** out of). But started just like that. Smoking a sec after WOT, and it got worse over a couple years. Check if you have exhaust pressure coming out of your oil cap. Do a compression test or a leak down test if you can. You can ignore for a good amount of time. The harder you ride it the worse it will get. Mine eventually blew the rear main seal out so it just pissed out any time the car ran haha.

SICAMG

You will notice it at higher speeds because you're pulling a strong vacuum on the engine when it is in a decell / down shift mode which will pull oil more easily into the intake through rings or seals.

Sulaco

it's rings vs seals that makes all the difference here.

if it's rings, then I'm smoked. Time for a rebuild!

But if it's seals, then that's a way easier, cheaper job that I can probably DIY. Is there a way to know which one it is?

Sulaco

How do I check for exhaust gas coming out of oil cap? Cap off, hand over cap, rev the engine, see if it pushes back?

drothgeb

Yeah if it's bad enough you'll feel pressure at idle(will do this if it's either though sry) You can also pull the valve cover, do a leak down test on the cylinders. If it's ring the pressure will go into the crank case. Make sure the valves are closed on the cylinder you're testing

Sulaco

Got a video of the issue today

Sulaco

For what it's worth the oil cap is cresting zero suction at idle. Compared it to my C55 and both behaved the same. No pressure differential from either motor at idle with hand over it.

SICAMG

Sulaco take the cap off and have some one rev the engine and see if any air / pressure comes out. If no pressure ...that is great and you can look towards valve seals.

Sulaco

Oil cap off, engine warm, zero push back at idle on oil cap. When I had my wife sit in the car and hit 4k RPM, I felt a very very faint pushback. The pressure was so slight I couldn't tell if it was real or if I was imagining it. So I pressed a plastic ziploc bag tightly over the hole to verify: just a very slight bit of pressure from the engine when revved to 4k RPM.

So is that an indicator that my rings are starting to go? The car is sitting still so the blower isn't engaged for this test.

SICAMG

No... that's an indicator that it is NOT the rings. Things may change under boost but I would say not rings and must be valve seals.
So valve seals from FCP Euro are around $50.00 plus whatever the labor is but it is time consuming.

Sulaco

well if you're right then this is great news. Being a wagon I wanna keep the numbers matching engine.

But it is high miles at 185k and I beat the absolute snot out of it every day. So if the motor needs rebuilt i fully deserve it.