Rebuilt/Swapped engines in car

[ShauKnee]

When someone in the marketplace thread says that they rebuilt their engine or swapped the engine and has approx # of km's on the engine. How can you tell if the # they told you is anywhere close to what is really on the engine?

[kwazy]

You can't, but if it is totally off like if it is an engine with 50k and they said that they rebuilt it but in actuality they never did, any mechanic will be able to tell.

If they lie about a few km's here and there you won't know.

[ShauKnee]

Oh okay, what if they say it was swapped? how can a mechanic tell then? i'm thinking they could probably just give me an estimate on the kms of engine?