Maybe a transmission issue?

[patcal]

I think I have a tranny problem on my 2004 S60 2.5T with 186k. My car is making a clunking sound when I give it gas & when I let off. Only notice it in stop & go traffic. Seems to do it in auto or geartronic mode. Only had the car since Feb. 2021. Last June I had the tranny fluid replaced with Valvoline Maxlife. There are no codes & the car drives fine otherwise. I tend to panic in these situations. Could this me a bad motor mount? Any thoughts would be helpful.

[Krons]

Could be bad motor mount, could be CV joints. Checking the bottom front and top mounts isn't hard to do. A bit more work to get to the passenger lower mount. All three of these are pretty straightforward DIY, the other two a bit tricky.

I'd check mounts and CV shafts before worrying about the trans.

[- Pete -]

I think your suspicion of a collapsed motor mount is probably pretty likely. Although, anytime you are on the throttle & then let off, the front suspension gets loaded a bit also. Just saying have a real close look at all 5 engine mounts but also inspect the moving pieces that make up your suspension as well: control arm bushings, ball joints, top end of front strut assemblies ie top bearing plates & spring seats etc.

Typically transmission maladies present themselves most notably at shift points, whether it be up or down shifting. From your description it seems to me as if the car is still shifting well.

[patcal]

Thank you. I tend to always think the worst. The car shifts great up & down. No delayed shifts or anything I have read about these transmissions. I am now off to read up about mounts & CV testing.

[- Pete -]

The round hydraulic engine mounts (X2 in P2’s) would be lowest on my list of culprits. I do think it’s important to check them though. Here’s a couple effective ways to check them. Use a jack & 2x4 under the oil pan & gently lift the engine up. If you can hear slurping and gurgling noises emanating from either of the hydraulic mounts, their contents have been spilt by a split in the rubber (usually presents itself as a rusty looking stain around the area of the mount that is impossible to remove). Like I mentioned, I doubt the noise you’re hearing is due solely to a failed hydraulic mount, but if you find one is failed I would highly recommend replacing it. When these fail, the engine can move/vibrate/oscillate in a manner it wasn’t designed to. This, in turn, can lead to a premature wearing of your CV axle’s cups & rollers (a bad thing).

For the other 3 mounts (top torque, bottom torque, and mount by crank pulley) you’ll have to use your best judgment.

[- Pete -]

One more thing to check, make sure all the fasteners securing the front subframe to the main frame are tight. There’s a slim chance one has loosened. There’s also a slim chance of a worn subframe bushing. All things to consider while you’re at it.

[erikv11]

I had a P80 Volvo with a bad control arm that clunked like this. The bushing was shot where it mounts to subframe. How old are the control arms on your car?

I could replicate the clunk in the garage by shifting the trans back and forth between F and R so I had a helper do that while I listened around various places. It was pretty easy that way to pinpoint it to the wheel area on one side. No clunk whatsoever when shifting with the front of the car in the air on jack stands though this is not the best counter-test. Replaced control arm, solved it.

[Blacklab467]

Mine did that about six months ago, it was a precursor to the passenger side CV joint failing. I was concerned about the transmission as well until it developed into an acceleration vibration that gradually got worse and and undriveable. Telltale sign of CV joint failure in my case.