my 92 dakota died, tried to replace the timing chain, too little too late. I have no compression , either the valves are bent or the pistons were destroyed, iether way she is gone, Warning to anyone with an early 90,s 3.9 v6, if you hear that rattle in the front of your motor. FIX IT immediatly. P.S. anyone out there looking for a nice prts truck in the Baltimore / washington DC area.

 

Great tip for anyone with any engine that is making noise. Don't make it worse by keep on driving it.

 

im not exactly sure if this is true or not, but my dad (manager at an auto shop, been working on cars for prob 30 years) says the motor on these is non-interference (this would mean that the valves and the pistons cannot touch each other when fully extended). if that is the case, and the issue was just the timing chain, then the reason you have no compression is because your timing is now completely off.
(valves are open when they should be closed, or something like that).
you cant just pop the timing cover off and replace the chain, you gotta make sure the top half of the motor is where it is suppose to be in relation to the bottom half, hence why its called a "timing" chain.

 

I concur with your Dad.

 

If the key way on the crank and the cam and the timing marks all line up how can it be wrong.

 

maybe you can still have the marks line up and be 180 off

 

the bottom and top gear turn at different rates, so as crazy said, just because they appear lined up doesn't mean everything inside the motor is lined up right. lack of compression definitely tells me that the valves are probably open when the engine is trying to compress