Bad engine

I have a 2002 Toyota Tacoma, 6 cylinder, with 78K and am told by 2 mechanics that the engine needs replacing – it has loud knocking noise. I have always changed the oil on time, never overheated the engine or driven with no oil. The same mechanic has taken care of it since I got it at 15K.

Any ideas about how/why this would happen?

Have your guy use a stephascope to listen if knocking top or bottom or motor, sorry for spelling.
If its the bottom it may be a spun rod bearing and your guy maybe able to drop oil pan and replace?
If not you can replace motor with junkyard motor or drive it till it quits hoping it stops knocking. Doing this you know it will stop at the worst time.

Is the knocking present at idle and at elevated RPMs?
Did this noise come on suddenly or somewhat gradually?
Is the knock sound a steady one or is it somewhat erratic?
Automatic transmission?

Just trying to formulate a wild guess here.

We have had some posts about Tacoma engines and camshaft gear retention problems, perhaps your noise is in a part other than a worn bearing.

You may try a search on “Tacoma engine noise” if not here then on a Toyota Forum. 78K is way early for engine replacement.

From 1998 thru 2002 Toyota 3.0 V6 engines had a sludge problem. Even if you changed your oil regularly there’s a chance it will still sludge up. The only way to prevent it was to use synthetic oil or to change oil every 3k miles RELIGIOUSLY.

When Toyota finally admitted their sludge problem, the letter we got from them for our 1999 Sienna (3.0 V6) recommended changing the oil every 5K miles - and not the 7.5K miles in the owner’s manual. That 5K interval has worked fine for us for 145K miles using dyno oil.

With that engine…I’d be using synthetic…but I tend to keep my vehicles to 300k miles.