How does one know that the engine mounts are gone or about to go?

 

Not sure how easy it is to detect with an auto, but with a manual, I think it's easy (assuming what I'm noticing is blown front & rear mounts...). At low speed, shift into 2nd, and slow down to where it's below 1500 RPM or so. Stay on the gas lightly, then take your foot right off. If you feel a repetitive forward-backward jerking that goes more than 1 or 2 jerks then I think it means they're shot. I'm experiencing this on mine... it's most noticeable in slow or stop'n'go driving. It's actually quite annoying. I'd like to put polyurethane mounts in there, whether they're homegrown, ES or PR brand mounts

 

So can i try the same by putting the auto in "2" taking it to less than 1500 and then letting go?

 

I guess you could try... I'm not sure with automatics though, the torque converter may soften it out (a manual works well since the clutch is a tight mechanical bond, while the TC in an auto is hydraulic)

 

Brake torque the car somewhat quickly. Put your emergency brake on hard, stand on the brake pedal and then mash the gas pedal. If the mounts are bad the engine will move up and down, it helps to have someone looking at the engine with the hood open. I have a set of good mounts for sale from my Maxima, I upgraded to Place Racing mounts a few months ago, and just kept the stock ones in case they are needed. Automatic tranny cars have the expensive electronic mounts, but you can uplug them and use the manual tranny ones with no problem or check engine lights or anything.