CVT Downshift Clunk

[jcgct]

Hi Everyone,
I'm going to say within the past month or so I've been noticing a little *clunk* sound when my 06 Murano SL awd (~60k mi) downshifts. This can happen while in motion after I tap the accelerator to accelerate and it returns to lowest cruising gear or when I am driving out and about and decelerate to a stop. It does not matter what RPM, no matter what speed. I can be in a parking lot going 5mph, if I tap the accelerator lightly and remove my foot, it's as if after I take my foot off the accelerator, it clunks. Same thing on the highway at 70mph or a side street at 35mph or whenever I come to a complete stop. There is always a *clunk* as I slow down. It happens all the time and this is with no awd engaged. There is no degredation to acceleration performance and no odd feeling when decelerating. These are not loud, jarring, vibrating thuds but clear precise sort of quiet clunks.

Thanks for any input

[nitely]

Check your CVT and TC fluid level. Check for fluid leaks underneath. Its also possible the clunking is coming from the motor mount or the front suspension.

[njjoe]

I would suspect worn cv-joints or a broken motor mount. Could also be control arm bushings.

-njjoe

[jcgct]

Originally Posted by nitely

Check your CVT and TC fluid level. Check for fluid leaks underneath. Its also possible the clunking is coming from the motor mount or the front suspension.

Thanks Nitely, I know nothing about motor mounts, so can't comment on that. And I could see the front suspension but if it were not for the fact that this clunking sound is directly related to the moment I take my foot off the accelerator. This happens on perfectly smooth pavement. I can accelerate and then cruise (of course there is a clunk when I stop accelerating and take my foot off the pedal), and if I lightly tap the accelerator and remove my foot there is a clunk, lightly tap/remove and then clunk, lightly tap/remove foot/clunk. Then coming to a stop sign (slowly or not), I break and eventually there is a clunk, or maybe even two, before coming to a complete stop.

[jcgct]

Originally Posted by njjoe

I would suspect worn cv-joints or a broken motor mount. Could also be control arm bushings.

-njjoe

Thanks njjoe, the only experience I have with worn cv-joints is when you turn and get that tick tick tick sound. Had that with a honda civic many years back. This occurs as I described in my previous reply to nitely. It occurs reliably ALL THE TIME, fast/slow, hills/flats, turns/straight, smooth/rough pavement.

I'll make an appt to have it looked at and see what they say. I have my ext warranty through Carmax so, unfortunately, I must take it there first. It's proven to be a waste of time because they sometimes ultimately recommend me taking to a Nissan dealership but have to go there first. Argh.

[nitely]

Motor mounts are basically 4 big brackets with cushions holding your engine and tranny to the cars main frame. One on each 4 sides. When the cushion starts to fail then you get excesssive movement on the enigne when accelerating or decelerating. You can easily check this by putting on the ebrake and stepping on the brakes hard, and then accelerating the engine on drive. IF the condition is real bad (more than 1 motor mount is bad) lots of movement can be seen.

[jcgct]

Originally Posted by nitely

Motor mounts are basically 4 big brackets with cushions holding your engine and tranny to the cars main frame. One on each 4 sides. When the cushion starts to fail then you get excesssive movement on the enigne when accelerating or decelerating. You can easily check this by putting on the ebrake and stepping on the brakes hard, and then accelerating the engine on drive. IF the condition is real bad (more than 1 motor mount is bad) lots of movement can be seen.

Thanks nitely, I had to YouTube motor mount testing to see what you meant. I understand now what you and njjoe were referring to. Literally, upon acceleration the engine rises off the frame and when you release the accelerator, it falls and clunks back down on the frame. YIKES!

I am right around 60k+ miles and now I've read that these engine mounts and the rubber inside can wear and get torn. They are in god-forsaken places, so I'll leave it up the experts and, as usual, just open the wallet and let the money fly out.

[jcgct]

Nitely, no unusual engine movement when I performed the test as you had described for bad/failed/broken motor mounts. No clunk when revving in place with emerg break on, brake pedal mashed and in Drive.

I'll call now to start the dreaded process of scheduling service for the Murano.

Thanks.

[jcgct]

Dropped off the Murano this morning and within an hour and a half got a call telling me that looks like the front axle is loose. They said they will tighten it up and then take it for another test drive to see if that took care of the problem.

So, very well could be that it's a suspension issue, just like you guys mentioned.

I'll report back when I know more.

[jcgct]

I'm not exactly sure what "tighten up the axle" means, per se, but apparently doing that did the trick. No more clunking, so says the shop. I'll pick it up this evening after work and decide for myself if the clunking is a thing of the past.

[jcgct]

Yup that was it. A tightening of the axle did the trick. No more clunking when I take my foot off the accelerator or when I come to a stop.

[Pilgrim]

Interesting phrase - and I have NO idea what "tightening the axle" could mean. If you learn any more about it, please share with us.

[Halwg]

Sounds like dealer BS to me.

[Pilgrim]

Originally Posted by Halwg

Sounds like dealer BS to me.

I suspect it lost something in the translation to us. There may be some device securing part of the driveline which was loose...?

[Halwg]

Originally Posted by Pilgrim

I suspect it lost something in the translation to us. There may be some device securing part of the driveline which was loose...?

Possibly, but I have found over the years that rather than explain exactly what was done to the vehicle the service manager will use some very vague terms, and "tightening the axle" sounds like one of them. I generally ask them to explain (or as Ricky Ricardo used to say..."splain") exactly what they did.