Just in case anybody else is reading this with the similar symptoms, I think it is the valve stem seals based on this article at
https://dannysengineportal.com/valve-stem-seal/:
Quote:
Idle and Stop and Go Driving
Bad valve stem seals will show themselves during prolonged idling at stop signs or stop lights in congested city conditions. When the vehicle sits at idle for prolonged periods, high levels of vacuum at the intake manifold result. The high vacuum attracts oil in the heads to congregate around the valve stems. Upon acceleration, the oil gets sucked past the seal and down through the valve guide. Huge clouds of blue-white smoke exit the tailpipe after each acceleration from a stop. The burning smoke will disappear during cruising or highway speed.
Off-Throttle Braking
Evidence of valve seals being compromised will also show up during off-throttle braking. More so when descending a steep downgrade where the accelerator pedal remains static. High manifold vacuum, coupled with the downward slant of the engine, oil collects toward the front of the valve cover. Upon pushing the accelerator after a long coast, burned oil will exit the tailpipe in large amounts. After that the smoke will stop again.
|