Sudden onset of oil smoke

[brianlay]

I was driving my 3.2 Carrera hard at the track this weekend and mid-way through the second day started to get large clouds of oil smoke during decel.
Prior to that I hadn't seen any smoke.

Thought maybe it was oil into the breather pipe from hard cornering and hilly track but we couldn't see any traces of oil in there when we inspected it, and we hadn't added any. Level slightly above the bottom dipstick mark.

The engine has about 15K on a complete top end rebuild including rings. It smoked some before the rebuild but never like it does now....and I had some pretty worn exhaust valve guides.

Through the remaining sessions it continued to smoke but seemed to subside a little bit. No smoke at idle or on hard acceleration.

Any suggestions about how to diagnose this, besides the usual compression check and leakdown tests?

[E Sully]

You could remove the exhaust and look at the exhaust valves and guides.

[Por_sha911]

Assuming no overheating or over-revs, a bad valve guide? Does it make any new noises?

[brianlay]

No new noises....and seems to run strong

I can't believe guides could wear out in less than 15K. I'm hoping there's another cause.

[brads911sc]

How is your compression and leak down numbers?

[brianlay]

Examined spark plugs and found 5 grey/brown ones and number 6 very black. Didn't seem like oil fouling (i've had that).
Replaced the injector and problem solved.
Runs much smoother and no smoke!

[kodioneill]

Well done!! good diagnosis and repair.