Potentially Bad Things

[APBAinMaine]

I'm afraid of what the answer is going to be as I've been searching and following several somewhat similar threads, but here goes.

I have a '97 Expo with a 4.6L that I bought for plowing, moving the band. So far, I love it. However, while I was parked, idling while I hooked up the plow to move it the other day, something happened. When I went to move there was *gasp* white smoke. Not a lot, just like a puff. After that there was just a little bit of wispy exhaust. I didn't think much about it because it's been abnormally humid here.

Well, I took it in for some unrelated service today, and when I got home was disconnecting the plow (in its new location), and left the truck idling while I did. This time when I backed up, a new pope had been elected. Once that cloud cleared, it was fine again.

I'm thinking head gasket and hoping I'm dead wrong. There have been no codes, and it's otherwise running great (notwithstanding a small exhaust manifold leak that I'm ignoring). I've experienced a blown head gasket before, but this does not seem to be the same symptom. I put my had over the exhaust pipe, though, and I'd definitely have to characterize the emissions as vapor. *sigh*

[bstedh]

It could still be a head gasket or crack somewhere. I have had them where you will get the smoke until the engine warms up and the heat expands everything and it seals itself back up. I have also had one where there was a bad head gasket but if you let the vehicle sit long enough the bad spot would rust up and seal until you put some stress on it like high rpm and then it would let go again.

I can't think of any thing else that would cause your white smoke but someone else on here might have more ideas.

[APBAinMaine]

A bit more info. Both times it has happened was when I was dropping the plow. I left the truck idling, then lowered the plow, then removed it. When I backed up, smoke/steam. Perhaps the angle or something? The truck has been completely warmed both times it's happened. I drove the hell out of it today (unintended, but was helping someone move) and it was aces all day. Just choke it till it pukes, I guess.

[TBIRD430]

Have you checked the engine oil & the coolant?

Has it been "using" coolant?

[APBAinMaine]

Engine oil is normal. Coolant level is stable.