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I have a 1990 Caravan with a smoking problem - some blue puffs, but mostly white and only when the engine is cold, especially on damp, cool mornings. ?With 178K I’m sure it’s due for retirement, but oddly it passed a dynamic SMOG test a few months ago. ?I suspect a hairline crack in the head gasket, but it would seem to me the problem would not go away after warm up it that were the case. ? I only drive it a couple K a year - (Home Depot and back) and it is perfectly suited for that purpose. ?Hate to have to replace it with something similar with unknown problems. ?Suggestions?

My guess is wearing piston rings, how often did you change your oil, Black is gas, white is oil in my experience.

Blue puffs are due to a slight seepage of oil, either past the rings or through the dried out valve seals. Normal on an engine this old with this many miles. The white is moisture, but if only happens when the engine is cold, and never once warmed up, I doubt seriously the head gasket is compromised. The engine runs very rich when it is first started up on cold mornings, and that extra fuel also produces extra moisture, mixing with the moisture in the air.

Truck on. These are normal observations for your van considering the age and mileage. Drive it until something expensive breaks. Your worried about nothing.

White smoke when the engine is cold, particularly on damp cool mornings is perfectly normal. One byproduct of combusion is water. When the exhaust system is cold, you will see this vapor. As the car warms up, the exhaust system is hot and you won’t see the vapor, although it is still there.
The blue smoke may be due to bad valve seals. When the car is parked, the oil leaks down into the combustion chamber. As long as you pass the smog test and keep your eye on the oil level, this isn’t a real concern.

Don’t consider it ready for retirement just based on this.

As others have said, water vapor (moisture, a cloud) is normal from a cold engine. As they pointed out, your engine actually generates water vapor by freeing up the hydrogen in the gasoline (hydrocarbon) to bond with oxygen in the air and form H2O, and on a cold day it condenses as it exits the tailpipe. If it’s really cold out, like it has been lately on the entire east coast, the white cloud can continue all the way to work. It can also condense on cold exhaust pipes and drip out the tailpipe. This is all perfectly normal.

Honestly, on a 20 year old vehicle with 178K I’d consider an occasional puff of blue smoke as normal also. And pretty much harmless. It may over the years eventually affect the oxygen sensor and converter, but it may not…and at that age who’s to say it was the blue smoke’s fault? Everything dies eventually.

As long as you routinely check your fluids and do your scheduled maintenance you’re fine. And engine can run indefinitely burning a bit of oil as long as the level never gets low.

Happy motoring.