Nope, no time-serts or any other engine work for that matter.
172,000-miles and doing fine. WOT's almost every time its back on line.
Changed the coolant to Prestone 50/50 premix (mix with any color anti-freeze) and added the almighty "ginger root cookies" (Bars leak sealant pellets).
It hasn't owed me a thing for years.
When and how it finally does let go - it'll be long live the next Caddy