2001 Savana 1500 5.7 with 107,000 miles and no history of ever overheating has been intermittently having rough start and white smoke from tailpipe for months now. Van had complete tune up and new distributor at 96,000 miles. Symptoms started around that time. Van has never overheated and always runs on cooler side. Coolant overflow reservoir is often needing to be topped off. No external leaks detected and radiator/water pump/thermostat/hoses were replaced due to age last year. Van just started misfiring on freeeway very randomly. SES light comes and goes. Last time it was on, Pep Boys said it was misfire on Cylinder 6. SES light not on now. Van drove nicely down to shop...mechanic says, just based on fact that it is using coolant somewhere and puffing white smoke upon cold start, that it must be the head gasket. He has not done compression check, block test, or anything else to diagnose. Oil is fine. Does not look like coolant mixing at all. I am tempted to put some kind of Stop Leak in, since the symptoms are so intermittent and because he does not want to work on the van. However, the radiator/water pump/thermostat/hoses were all new a year ago, and I don't want to risk fouling anything up if that is not the case and it is not the head gasket. My mechanic told me, when I asked if it could be the intake manifold gasket, that I would have oil and coolant mixing for sure. He is convinced it is head gasket. Any thoughts? What kind of Stop Leak is best? Van will start and drive just fine some days, with initial white smoke upon start up that clears up when you start to drive it. Other days, it misfires randomly on freeway and will throw a code (misfire on cylinder 6) that goes away on its own after a couple hundred miles. Again, there is NO oil and water mixing, and the van NEVER overheats and NEVER has, in 30,000 miles of owning it. Main symptoms are rough start, rough idle, and white smoking upon cold start that begins 30 seconds after idle and goes away when you drive it.
