However, on arrival in Canada, the team confirmed the upgrade would be delayed until the French Grand Prix in two weeks' time.
Renault and Honda are set to bring updated engine components to this weekend's round of the championship, with the outcome of the upgrades set to be a factor in Red Bull's decision-making exercise for 2019.
Teams can only use three engines per season without incurring a penalty.
A Mercedes spokesman told Sky Sports: "Although we had hoped to introduce PU2 [power unit two] this weekend, a quality issue means that this has now been delayed by one race".
"So all Mercedes-powered cars will be running PU1 for this weekend, too, before receiving new units in France".
Mercedes lead Ferrari by 22 points in the constructors' standings going into the Canadian Grand Prix while Hamilton is ahead of Vettel by 14 in the drivers' equivalent.
Another went even further, putting the Ferrari slogan Forza Ferrari alongside a GIF of a Mercedes Benz vehicle ornament. If the four-times world champion wins again on Sunday he will equal Michael Schumacher's record of seven victories in Montreal.