I had the same smoking front brakes experience on a SUV but not on vanagon

according to the mechanic:
- failed brake hoses (brake fluid returning too slow of not at all)
- failed brake caliper (not retracting fast enough or not at all)
- failed brake cylinder which gave same result as failed brake caliper

it quite hard to pinpoint the culprit so I had the whole front brake
replaced to be on the safe side.