Mechanics lien rights arise when work is done which permanently improves the underlying project property (i.e. the real estate). So, if repairs were done to equipment which is a permanent fixture attached to the property (rather than on movable property - like a truck, tractor, etc.), then it's possible that work on an engine might give rise to mechanics lien rights. However, for work done on movable property, mechanics lien rights would likely not arise. Instead, contract claims or other legal claims may be more appropriate.
For more background on Maine mechanics lien rights: Maine Mechanics Lien Guide and FAQs.