2010 Mazda B4000, 192,000km (120,000 miles) manual transmission
4.0L SOHC

Just bought it, I knew it sounded like garbage and now I’m just exploring my options. 

After much research I’m fairly certain it’s the timing chain (death rattle). Other than that this truck is in beauty condition. 

The sound is the worst at cold start but then seems to die down into a more consistent ticking sound once hot and has been driven a little bit. Sound does not really go away though, as best as it gets it you can hear it if you strain to listen while driving. 

Also based on some research if the sound is this bad and consistent, I think it’s past the point of just doing the tensioners. My current options are to remove the engine and redo the timing chain system or just put a new engine in it. Unfortunately I live in an apartment and don’t really have an option to do any of the work myself so it’s gonna be at a trusted shop. 

Current costs are $5300 for the timing chain or $12800 for a new (rebuilt) engine with a 3 year warranty. 

The reason I’m considering a new engine is that I have no idea how long it’s been driving like this, I got it off an elderly woman and the truck had been sitting for a year before I bought it. 

Would I know if it jumped time or if the chain had started to cause further engine damage? Other than the sound it operates as it should. 

At the end of the day, should I drop a new engine into it or am I just being paranoid?

Timing Chain or New Engine?