Puzzling problem

[Badhorsy]

I recently became the proud owner of a 1987 BII Eddie Bauer. It has the 5speed with manual hubs and manual transfer case. Upon the initial shakedown drive the truck ran poorly. Since I got it I installed new Autolite platinum plugs and wires. A new thermostat. Flushed and cleaned cooling system. New valve cover gaskets. New PCV valve. New fuel filter. New external frame mounted fuel pump. Put a can of seafoam in the gas tank. Also seafoamed the engine via the brake booster vacuum hose. Also installed a new cap and rotor on distributor. Engine runs much better except for an annoying problem. The engine smokes sometimes really bad when I'm in stop and go traffic. I know there's a chance it could be bad valve seals or worn valve guides but there's a catch. It only does it intermittently. So I did an oil change. I used the Motorcraft FLHP filter ($20!!) and went with 10w40 motor oil. Seemed to help some with the smoking but not too good. So I drained the 10w40 and put 20w50 in it along with a can of Restore engine treatment. It came highly remommended and I researched it good before putting it in. But the most puzzling thing about it is out of a typical week of daily driving 90% of the time it runs great.hardly any smoke. But once or twice every three or four days I can be sitting at a stoplight and it will begin smoking from the tailpipe like its on fire. I mean really bad. When I leave light it will gradually clear up and run perfectly again for a few days and do it all over. I'm stumped as to what this problem could be. Sorry for the long winded post but I wanted to be clear about how its acting. Any ideas? Thanks for all of your help...

 

[wildbill23c]

Is it using any oil? What color is the smoke? Could just be that your running rich, not sure how that's adjusted with the fuel injected engines but sounds to me like it's got something to do with getting too much fuel at times.

 

[Badhorsy]

Its definately oil. When it begins smoking you can really smell it. I'm having to add maybe a half quart a week. I'm not thinking its fuel related because its definately bluish white smoke. If I'm correct an engine running rich will release blackish smoke from the tailpipe. And the previous owner had a new FPR installed I think the fuel system is sound. Any more ideas guys and gals?

 

[Gasrunner]

Sounds like valve seals. Especially if it still runs Smooth while in gear at the light.

 

[Badhorsy]

I was thinking maybe those too but can't understand if it was the seals why does it only smoke occasionally and not every time I drive it?

 

[RonD]

Yes, it does sound like valve guides/seals are leaking.
When engine is idling the intake manifold has its lowest pressure, or highest difference with outside pressure, so highest vacuum.
This causes a leaky valve guide/seal to pass the most oil.

As you accelerate the intake pressure becomes more equal to outside pressure so less oil is pushed into the intake valve guide, so less smoke.
But it is always burning oil, just more when idling.

Why is it random?
Valves rotate in the guides, could be valve stems have slight out of round issues where gap is larger and smaller, just guessing.

You can replace the valve seals without removing the heads, that would lessen the oil burning, but removing the heads would be the best long term solution.

Oil smoke while accelerating is usually from leaking rings, more RPMs = more oil burning.
Oil smoke at idle and when first accelerating is from leaking valve guides/seals, higher RPM = less oil burning.