Some follow-up questions regarding the timing chain issues on 4.0 SHOC E- VIN number engines. I drive a 2002 Explorer Sport Trac with 94,785 miles. Over the last several months I am hearing a small amount of additional noise from the engine mostly when cold but still not as quiet as it used to be. There is also a tiny bit of vibration at idle. I have tested the engine as described in the TSB by driving with the transmission in 2nd gear between 2,000 and 3,000 RPM and do not hear any noise like an engine ping. I have read through the many threads and posts about this issue but am still unclear on how to proceed. I purchased the vehicle 2.5 years ago with 79,850 miles and it is in excellent condition. I would like to keep this truck for the long haul.

Is this a problem that a dealer or qualified repair shop can diagnose just by listening to the engine or do they have to tear it apart?

Is it worth first trying to replace the front and rear chain tension springs as some have suggested?

I have checked several of the online repair cost estimators for my area and they suggest a cost of $1,900 to $2,400 for 19 hours of labor and parts to replace both the front and back timing chains and gears. At this price some have suggested it is better to just replace the engine. Is this the best approach considering the relative low mileage of my engine and about how much more would that cost to put in another engine?

Any other suggestions or advice would be appreciated.