When the engine of a vehicle locks up, is it wise to get the motor rebuilt by a mechanic? What could go wrong if done incorrectly?
Yes and everything.
is it wise to get the motor rebuilt by a mechanic?
No. Paying someone to rebuild a motor is hardly ever worth it.
When the engine of a vehicle locks up
But , lets back up a bit. Why would you jump straight to the conclusion that an engine needs rebuilding/replacing? FIRST, you need to find out why your engine locked up, and then go from there. I can think of several reasons that can cause this which don't require throwing away the engine.
What could go wrong if done incorrectly?
There is a lot of room for mistakes when rebuilding an engine. Most mechanics do not know how to do it right because they don't need to. These days it's just not done often. It needs to be done by someone with experience.
If the engine doesn't turn over after I turned the fan belt with a socket, would it be ok then?
did you try removing the accessory belt?
Putting transmission in neutral?
Removing the spark plugs? Looked down in the hole?
Checked the flywheel? Starter? Clutch?
Timing belt/chain?
I think that buying a used unit is usually the way to go.
Unless it’s a common / simple to repair issue like piston deterioration on a VW 1.4L TSI - things get really expensive very fast.
But in the case of a locked up engine, when you know something is very seriously wrong - it’s best just to get a different unit.
(Also, sometimes when rebuilding engines, you just have to get new parts - like a new cylinder block, and then you either have to buy a good used engine or buying new parts. Either way it makes the already expensive rebuild even less economically viable)
Assuming the mechanic manages to get the engine to function correctly (sometimes they don’t and engines have terrible valve clatter, low power, or other issues),
Usually poorly rebuilt engines have oil consumption issues, or just don’t last long after the rebuild.
If you need help troubleshooting an engine that won't turn over, then please start your question with that instead of working bass ackwards.
