Are 2005 4.7 junk? Friend has Durango with dead motor. Used motors go for $1000 or so. Should we put on new timing chain/tensioner when we swap motor? He wants to get it running.
Why is his motor “dead”?
Without a whole lot more information it’s impossible to say what should or should not be done to the used motor. You’ve really given us nothing to work with here.
This is easy: if not repairing the original engine replace every thing that could fail and cause expensive and difficult repair. Part two: only the owner can decide what amount of money they are willing to spend.
There’s a saying amongst auto mechanics that Chrysler makes good engines except for the ones with sizes that end with .7. I’m not sure I feel quite that strongly but I haven’t been impressed with the 4.7 as being more durable or reliable than most other engines.
Without knowing exactly what’s wrong with the dead engine or what condition the used replacement is in I can’t recommend much. But I don’t think I’d bother with replacing all the chains. They don’t seem to fail particularly more than other timing chains.
The 4.7 is basically a 3.7 with two more cylinders & they both have the same problems which isn’t timing chains . They spit out rocker arms & drop valve seats . If ever overheated they are much more likely to drop the valve seats .
Motor has knock. Bad rod? Bearing? Wrist pin? Whatever. Used motors are not too expensive.
I used to have 2 guys that worked for me with this engine in their Grand Cherokees both with over 280,000 miles. Neither had ever been apart.