Original Video/spark plugs 9 months ago VIDEO: Spark Plug Insulators And Flashover Share Tweet Print Email ImportCar Staff Writers, View bio Bio Recent Posts Popular Posts ÜRO Parts Introduces Lower Radiator Hose For BMW 3-SeriesPenray Now Offers New Tough Max All-Purpose CleanersMotovicity Speeds Into 2018 With Its Newest Event, Never Lift24 Sessions On Tap In 2018 For Bendix In-Person Brake Training SchoolDorman Wins 2 Awards At 2018 O'Reilly Auto Parts Manager's Conference Nissan Working On Brain-To-Vehicle TechnologyTech Tip: Honda Accord And CR-V Rattle At Start UpMAS Industries Introduces 97 New Part NumbersOTC Introduces Tech-ScopeRobinair And MACS Worldwide To Provide Free Section 609 Test Prep Webinar And Online Test Andrew Markel shows the importance of keeping a spark plug’s insulators clean to prevent flashover. Sponsored by Denso. Gabriel Velazquez Flashover happens because the cop boot is crying uncle, and nobody ever sells customers new coil boots, because the industry has not made it a known serviceable item. Whenever you hear tune up these days, nobody mentions new coil boots, which usually fail long before a vehicle even needs spark plugs. I have seen them leave tracing in as little as 25k miles. You have to be an absolute slob to gunk up a plug enough where it would cause flashover. Some smudging on a plug will not do anything.