Not tested it, but maybe this will work, but I recommend you use pickups instead of markers for this type of script.
local myMarker = createMarker(3493.390381,-2223.425293,15.378421,"corona",3,225,255,0,255)
function markerHit6(hitElement)
if (getElementType(hitElement) == "vehicle") then
fixVehicle(hitElement)
destroyElement(source)
setTimer(function() myMarker = createMarker(3493.390381,-2223.425293,15.378421,"corona",3,225,255,0,255) end,30000,1)
end
end
addEventHandler("onMarkerHit",myMarker,markerHit6)