I drove my truck 20 minutes to school. Ran fine after the usual hard cold start. Turned it off, sat about 20 minutes and then turned it on and it had a pretty bad clunk. It was mis firing and I was waiting for it to go away for about 10 seconds, noticed the smoke and turned it off. Turned it on again a few minutes later, misfire was gone and there was no clunk but it still was smoking and Less than the first turnover. I checked my fluids and my oil looked fine, checked my coolant and the reservoir was pretty much empty. The system was fairly pressurized too. The smoke didn’t smell sweet. But it was very thick and bright white. Hoping its just spark plugs or something. Anyone have any ideas besides blown HG?

 

Welcome to YotaTech.

"Bright white" exhaust is usually an indication of water (coolant) leaking into the exhaust stream. If you hold your hand in the exhaust, it may get wet, rather than oily or black. The lack of coolant in the reservoir is confirmatory.

I don't think spark plugs can cause a coolant leak like that. While I don't know an explanation for the "clunk," I don't see an obvious way to avoid removing the head.