A week or so ago I noticed that when I put my Cube in reverse, or drive, and don't move, the drive belt tensioner seems to rattle/oscillate loudly. The sound will disappear as soon as a load is put on the engine. After driving for a few minutes and coming to stop (while in gear still) the sound is gone.

I ordered a replacement serpentine belt and tensioner and replaced the belt yesterday. I manually tested the old tensioner and compared it's smoothness in spinning and movement with the new one, and there is no difference - the old one still spins smoothly and has just the same amount of play as the new one. I haven't replaced the tensioner yet because I'm not certain that is what's causing my problem, and also I don't have a way to support the engine since I can't actually get it off without dropping the engine (thanks Nissan).

Does anyone have any ideas what it could be? I plan on having a local mechanic take a look, but before I do I wanted to have a better idea of what it could be. I was thinking it might be a spark plug issue, if there aren't enough RPMs at idle, but the rattling stops after driving. I did notice once on my OBD2 reader (using Torque Pro) that there was an issue with the evap system, but I only saw that come up once on the test results, it's passing all tests currently.

Car specs are:

2009 Nissan Cube 1.8L 230,000mi Idle RPM: 950(approx, at idle it sits about 1 needle-width below 1000) MPG: 29mpg average (most of my driving is highway, 76mi/day) Temp: within spec, no overheating Other: no misfires on the ECU, no CEL, no warning lights on dash, all tests passed on OBD2 reader

TLDR: tensioner rattles and oscillates when not moving at first, then stops after being driven for a minute or so.

1 Answer 1


You have a bad tensioner. The problem isn't in the spinning idler, it's the worn bushing and dampener mechanism. You already own the new one. Install it. See this post to learn about the bushing and dampener.

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