2005 Mercedes-Benz C-Class - Not worth fixing?

Beautifully maintained older MB with 283,000 miles. Ran perfectly, never had any issues requiring engine work. Car started running sluggishly for a couple days, had to keep foot on gas at stoplight to prevent stalling. ( Check engine light has been on for 6 months - Crankshaft Position Sensor - mechanic had said to ignore “as it wouldn’t stop car from running”. ) No loud or weird noises…

Mechanic checked car - now saying car has no compression and says vehicle not worth fixing due to high diagnostics cost. Suggest replacing engine with used one for $2800. Nothing is “Broken”, I.e. piston rings shot, crankshaft broken, head gasket blown or anything of the type. Is this an electronics issue? Timing chain? Why would there be a sudden problem like this? Having hard time understanding/accepting that car is done for and just went ‘poof’ and died…

There’s probably nothing wrong with the engine. Changing the engine probably won’t fix it because it’s probably a sensor, electrical, fuel system or vacuum, or one of many other things.

He just doesn’t want to spend a bunch of time diagnosing it.

I would not trust the diagnostic skills of a mechanic that told you to ignore the check engine light for six months because a crankshaft position sensor won’t stop your car from running.

I have no idea what he is talking about a high diagnostic cost to rebuild your engine. If the compression os low, he would just have to do a wet test and if the compression cam up, it would need rings, if it didn’t come up it would be valves or head gasket. An engine cannot run at all, if it has no compression.

If your engine needs rebuilding at 283000 miles it is not surprising and yes it would be more expensive than a used engine, but I would want a second opinion because of what he said to you.