Why did this happen? The motor sounded Healthy and there was oil and everything on it ..

wow that really sucks bro

Rods don't just bend/fail for no apparent reason, especially at idle speeds.

How do you know for sure it's a bent rod? Have you taken the engine apart already?

If it's a bent rod, chances are it was bent originally in the 3.5 engine, yes? Sorry man

Yeah I took it apart , replaced it . And I don't think it was originally bent.. The motor wouldn't turn I think but the motor turned and stayed idling for 20 mins before it locked up and I opened it and was a bent rod :/

did you check all of the torque specs on the block? Impossible to know why but if it happens again you know something is off

sound like your engine has some unexplained history to share with you...

Please expand on this. Was it running and then seized? Was it already seized and then you somehow hot it running? Was it free to a point and then came to a stop while turning by hand?

Was the cylinder full of fuel or water when you tore it down? Any bent valves?

This is nothing new for the early year vq35 this is pretty common

I find it very hard to believe that a rod bent without doing more damage to the engine.
Just doesn't make sense.

This.

This^^ or the motor had no or little oil that's the only way i see this happening. the motor won't rotate without any oil causing it to seize up.I will assume this was an oil burner or the owner just never changed the oil causing this to happend. bent valves can interfer with the flow of the motor's flow and bang the pistons and brake a rod or two. Water can do the same and just cause corrosion and break the motor down like it has no oil. water and oil don't mix.

i have to disagree, having an engine idling for 20 minutes and bending a rod is not common.

Word!!^^^ a bent rod means that engine was driven hard and beaten. A rod bending on idle?! That's a first.

I don't know what you did to the engine but it is not easy to bend a rod. rods bend when you ingest water or possibly coolant if head gasket is blown or if it was running rich as in one injector was fully open and flooded the cylinder, but again, it had to be at higher than 750 rpm (idle speed).

theres more to this story I'm sure. You did fill engine with oil, right?

i have a friend who bent a rod on his 3.5 swap here in ky after about 5 mins of running he reved it up 3 times (KNOCK) lol i think he had the timing off some where he swaped the crank pulley out to the old 3.0 because he wanted to run the 3.0 timing instead of redoing some stuff but now hes got another in his and has not had any issues yet but i still bust him with my 3.0 after he had a tune and everything where both auto and i bust 3.5s all day so thats why i decide to keep my 3.0 plus 3.5's have issues with oil pumps ive heard

You only will bust his 4.5th Gen Maxima only....He had some timing issues apparently....

Liquid is not compressible!!!!!!