Replace timing set?
 

My sister was told by her mechanic that her 2001 Blazer needed a timing set. 187,000 mi. She said that it made a screeching sound sometimes when it started and occasionally lost power and stopped while running. Now it doesnt start but cranks. I read where a timing set change is seldom needed. I'm not familiar with this engine, but any suggestions on things to check first. Thanks

the timing chain is what connects the crankshaft to the camshaft. so one easy way to check if it broke is pull off your distributor cap and crank the engine. if the rotor doesnt spin then it needs a chain. but that wont tell you if it just jumped or brook a tooth.

i think most manufactures recommend a timing chain swap at like 100,000 miles. though they can go way longer then that.