Smoking at idle, valve seals or worse?

[5.0 Hatch]

I have an 01 and once it's warmed up, it smokes blueish at idle. No smoke on startup or while going down the road though. I'm leaning towards valve seals but 200k miles is telling me it could be rings. It's almost like flipping a switch from no smoke to smoke.

I changed the pcv and moved to 5w30 high mileage oil and nothing changed. However, I only put about 15 miles since those changes. Was thinking of maybe trying an oil separator.

Ideas? Car only has off-road exhaust

 

[CobraSam]

Best to start with proper diagnosis. Start with a compression test to rule out rings. Then move to a smoke machine. Valve seats will typically be showing blue smoke at all rpm’s and conditions. A valve opens and closes, that’s it. So it doesn’t really matter about any other engine parameters. I bought my car knowing it needed new valve seats and pistons (another story). That thing smoked as soon as I started it until the second I shut it off. You also might hear what sounds like a misfire coming from the tailpipes. Makes sense because the exhaust valve seats are never really closing.

 

[Roots-type]

What do the plugs look like? Always the first thing you check.

 

[52merc]

As said, pull and inspect plugs. Perform a compression test. 200K miles is a fair bit. Could be rings. Could be valve guides/seals. Could be both.

 

[MG0h3]

Valve seals actually leak more under decel as there is high vacuum.


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[5.0 Hatch]

I hate to even post this but I pulled the plugs and it's not pretty. Appears that they might be original which is hard to believe. Car runs much better but still have a little smoke with new plugs. I see number 2,6,8 appear to have oil and all are caked. Any ideas what I have going on here?

 

[Rich B.]

Don’t have a turbocharger by chance? The ceramic bearings seem to leak on those back in the days, valve seals a possibility also. My ‘67 one time I filled crankcase with kerosene and ran a few minutes at idle. Yup, it cleans things up; Marvel Mystery Oil is similar, don’t drive car or race engine while clearing.

Oil was terrible back in the ‘60’s. Just breaking out of the high detergent times if I recall correctly. Nope, car won’t start if running straight 30wt oil in January lmao.

 

[5.0 Hatch]

Figured I'd update this post for others that may experience this. It turned out to be fuel and ALOT of it. I ended up getting an obd2 scanner and the torque app and determined I had a non-working o2 sensor on the driver side.

The o2 sensor was completely disconnected. I went ahead and changed both since I already bought them and pulled codes again. This time it showed o2 heaters weren't working. After hours of research, I found fuse number 8 in the car was blown. I changed fuse and now all is well.

Still hard to believe the amount of smoke I was seeing just from bad o2's.

 

[52merc]

If you are running cats I hope they are ok. That much raw fuel can damage them.