I just bought a used 2003 Pilot with 62,000 miles. I quickly noticed a that I hear a faint rumble sound that lasts about 2 seconds at speeds between 30 and 40. It sounds like I ran over a very short and shallow rumble strip. It can happen very quickly as I slowly accelerate. It only happens once, but not every time that I slowly accelerate. It also happen as I am coasting at these speeds. I took it back to the dealer, but they are puzzled. They thought I was crazy until I took them on a test drive and we eventually heard it. They tried adjusting the sway bar, but the sound continues.
I’m afraid you likely have the failing torque converter that’s common to Hondas and Acuras of those years. It’s typically described as a rumble strip sound around 40 MPH under light acceleration.
I believe that lion9car is correct about the cause.
The transmissions on Hondas of this era are a real weak point.
I suggest that you take the vehicle to an independent trans shop (NOT AAMCO, Lee Myles, Cottman, Mr. Transmission, or any other chain operation) for examination. Have them diagnose and document the problem.
Then, if the vehicle still has the typical 30-day used car warranty from the dealership, take that documentation to the dealership and ask what they are going to do to fix the trans problem. If you have no warranty protection, then you can expect to spend ~1,500-2,000 $$ (or more, depending on your location) for a transmission overhaul.
Will the problem show up on a computer? I took it back to Honda and they could not diagnose the problem. No check engine or transmission lights on. It shook pretty good today, like I was driving over a rough spot in the road.
These trannys are prone to failure. Have it checked out ASAP, especially if you have a warranty period or can return it within a period of time.
I also think it sounds like torque converter clutch shudder. This may or may not set a code (show up in the computer). It would eventually if it was bad enough & went on long enough but you can easily have problems without the computer ever saying anything about it. Too bad too, since often dealers will hide behind a lack of computer info trying to convince people that there isn’t really a problem.
Have the rear differential fluid replaced. The clutches in the rear differential are sensitive to the condition of the rear differential fluid. And since you bought the vehicle used, you have no idea the last time the rear diff fluid was replaced.
The dealer did change the rear differential fluid for me before I picked it up. I am going to take it to an independent mechanic on Monday. Then back to the dealer. The warranty runs out on Wednesday.
Be very wary of the transmission in this vintage Pilot. That may be why somebody got rid of it. Very expensive.