- “I know you feel bad for what you did. And I do want to be friends with you. But I don't like being bumped. No one does! If you want to make friends, Diesel, you need to change your ways.”
Springtime for Diesel is the first episode of the twenty-first series.
Diesel is always bumping into the other engines and finds it very funny. It is his way of saying hello, but none of the other engines find it funny whatsoever.
One day at Arlesburgh, Diesel bumps into Daisy while she is getting ready for refuelling. Daisy crossly tells Diesel that the bumping could be bad for her swerves and springs, but Diesel just ignores her.
Out on the branch line, Daisy's springs give way and she ends up slanting to one side. She carries on to the next station to let her passengers off before heading to the Dieselworks. Meanwhile, Diesel bumps into Thomas before noticing Ryan passing by with Daisy on Judy and Jerome's flatbed. Thomas wonders what happened to her, but Diesel thinks Thomas is about to blame him for Daisy's accident and hurries away.
At the Dieselworks, the workers cannot find the required parts to fix Daisy. Mavis tells 'Arry and Bert that Den and Dart say she may have to be scrapped, horrifying them. They tell Diesel, but he again thinks that they are blaming him. Later at a level crossing, Paxton arrives to tell Diesel about the rumours, but this time Diesel has had enough.
That night, Diesel comes to see Daisy at the Dieselworks. Thinking she is asleep, he apologises for bumping into her and tells her that he only treats the other engines badly because they treat him the same way and blame him for everything. Nonetheless, Diesel admits that he wishes he could do something to make everything alright again because he likes Daisy, but he resigns to the possibility that Daisy may never want to be his friend.
The following morning, Percy arrives with new spare parts from the Mainland, including spare springs for Daisy and the workmen fix her up in no time. As she leaves for work, she spots Diesel. She tells him that if he wants the other engines to be friends with him, he has to change his ways.
So that is just what Diesel does. Whenever he sees Daisy and Ryan on the Arlesburgh branch line, he wishes them a good morning and no longer bumps into them.
- 'Arry and Bert
- Judy and Jerome
- Albert's Wife
- Trevor (cameo)
- Jem Cole (cameo)
- One of Dowager Hatt's Friends (cameo)
- The Film Crew Leader (cameo)
- Daisy's Fitter (mentioned)
- Arlesburgh West
- Arlesburgh Goods Yard
- Arlesburgh Yard Shed
- Arlesburgh Harbour
- Arlesburgh Maritime Museum
- Mavis' Shed
- Anopha Quarry
- Knapford Yards
- Harwick Branch Line
- Vicarstown Dieselworks
- The Mainland (mentioned)
- Joseph May as Thomas
- Christopher Ragland as Percy
- Kerry Shale as Diesel and 'Arry
- Teresa Gallagher as Mavis, Judy, Albert's Wife and some Passengers
- Tracy-Ann Oberman as Daisy
- William Hope as Bert
- Keith Wickham as Den and some Passengers
- Bob Golding as Sidney
- Tim Whitnall as Jerome
- Steven Kynman as Ryan, Paxton and Dart (uncredited)
- The title may be a reference to Springtime for Hitler, a fictional musical in Mel Brooks' 1968 film The Producers, his 2001 Broadway Musical adaptation of the original film and Susan Stroman's 2005 remake of the former film.
- In the Nick Jr. USA broadcast of this episode, it is paired with Unscheduled Stops.
- This is the first episode for several things:
- This episode marks 'Arry and Bert's only speaking roles in the twenty-first series and their last speaking appearances in an episode to date.
- This episode marks Trevor's only appearance in the twenty-first series, though he would appear in deleted scenes from The Fastest Red Engine on Sodor.
- A shortened version of the episode, narrated by Joseph May as Thomas, can be found on the official YouTube channel and the Nick Jr. website.
- When Trevor crosses over the level crossing, he has Stanley's whistle sound.
- In the overhead shots of Daisy on the flatbed in the Dieselworks, the flatbed's shadow is not rendered properly as it looks like it has been cut off at the back.
- In the US end credits, Steven Kynman is not credited for voicing Paxton, Dart and Ryan. Additionally, Keith Wickham is credited for voicing Dart.