Packard Forum Index » Post-War (1946-54)

Today I was driving my 1950 Packard. It was smoking. The smoke color was kind a gray blue. Not heavy but more than there should have been. Also as I was driving it would backfire. What is going on? Anybody. How can I correct this?

Usually blue smoke indicates oil burning, white is water and black is fuel. The backfire could be an ignition timing issue. Hope this helps.

Helpful to know if the backfire is out the carb or out the tailpipe.

As someone said depends on what end, but there's raw fuel or fuel mixture entering either the exhaust and the temperature is high enough to touch it off or it's backing compression through the carb as it fires. Typical causes; timing, misfire(no/intermittent spark - spark plug, bad/lose plug wire, cap/rotor, coil), or valve(s) sticking.
If it sits alot, the oil drains down and worn or gummy things stick. A dead cylinder with bad rings will send gas down into the oil and it can end up anywhere then plus thins the oil. Go through the spark electrical, check the timing and oil for gas smell/cleanliness, and run some valve ease or engine treatment.
Combined with blueish smoke, to me, it's pointing to possible a ring issue. Compression test is in order.

Probably not the cause of the smoking, but maybe worth mentioning. If the diaphram (sp.?) in the vacuum booster has ruptured you could be sucking oil into the engine. Check the line that connects to the intake manifold and see if is oily. Also, this would cause a vacuum leak and result in a lean mixture which could be causing the backfiring. Just a guess...

(o{}o)

Yes, do a compression test. I would bet on burnt exhaust valve.