I have 2010 civic ex 110K miles on it. Auto tranny. My car recently started making a "rumbling" type sounds when starting the car after long periods of rest. I.E. first thing in the morning or long day of work. The car only makes the noise while in park then gets louder when in reverse. Once I put the care into drive the sounds disappear. This only happens when car has been resting for long periods of time. Any help would be appreciated! Thanks

 

You've got a problem with your clutch seal for the reverse gear is my guess. Possibly valve-body related but either way try doing a partial flush and fill of fluid, and i'd take it to a mechanic. If it is from internal wear flushing some of the fluid wont help, but when you drain out some, you can look at the magnet on the drain plug and if theres like major excess metal on it, that's a clue, or if there are any metal or black pieces that come out. If this is in fact an internal seal, this requires a transmission disassembly (and for the cost of what the mechanic charges you may want to consider getting a used or rebuilt transmission).

 

Thanks for the heads up!

 

It was a broken motor mount that was causing the rumble and shaking! Stoked I didn't have to drop $3K On a tranny

 

A video or sound clips from you as to what circumstances will cause this issue is very important here. A failed reverse servo fork seal will produce a grind or complete breakage of reverse components.

I've seen this complaint many times on many vehicle types, and it is usually an interference or vibration issue caused by another part, like the exhaust, contacting the frame in the park or reverse position. When you shift to forward speeds, the engine rotates the opposite direction on its mounts, and the noise "goes away".

What was the last thing done to the car prior to this starting up, and please list any powertrain repairs or removals that have been performed on the vehicle, including the exhaust system.