Learn English – Equivalent of “see in a new light” for hearing

Plain as day ( can also be used with the physical reference you are hinting at):

• very obvious, quite clear.

  • The secret to our success is as plain as day - make a good plan and stick to it.

• easy to see or understand:

  • I looked at the list and there, plain as day, was my name on the list of winners.

also, plain as the nose on your face :

• to be very obvious.

  • There's no doubt that he's interested in her. It's as plain as the nose on your face.

(from www.dictionary.reference.com)

In (British) English, a painlessly idiomatic usage would be

Mechanic: Do you want to repair your car?

You: Yes, but please don’t go overboard.

As thefreedictionary points out, ‘go overboard’ literally means falling out of a boat, but idiomatically one can also go overboard on a task: ‘to do too much; to be extravagant’.

That can mean a range of things, from taking a task in general more seriously than it could possibly merit, to polishing thousands of tiny details that no-one could possibly ever see.

In the case of your example, the not going overboard scenario would involve the mechanic simply fixing the essential problem efficiently, and stopping there.

John’s colleagues would understand each other perfectly if one of them were simply to say, ‘John is going overboard again.’ They might or might not try to stop him, but they would understand that John is expending unnecessary time and effort, as usual.