I took my 97 accord lx sedan for a tune up today to a mechanic, and they did the whole works including distributor cap, rotor, spark plugs and wires. They also replaced a valve cover gasket and oil pan gasket because I had some leaks, which I was aware of.

They mentioned my front and rear motor mounts are cracked, the two side ones are fine, and quoted me 280 for parts and labor, which seems reasonable from what I've seen. But what are consequences or symptoms of cracked motor mounts? I mean the only thing I experience is a little vibration or light drilling when I have the AC on and I'm stopped at idle.

 

If the rpms at idle are fine, you will get the "vibration". You might also feel it when driving. You might also notice a "clunk" when shifting.