Still getting a thunk when going downhill - transmission?
 

2013 XC90 - Still getting a 'thunk' when I crest a small hill - although it doesn't happen if the car is in neutral. Replaced both the upper and lower engine mounts.

I plan to try to replace the transmission fluid - the car has just tipped 100k. Can someone confirm the correct method for a 2013 model? I've found a couple of different approaches but not sure which is correct for my year.

Also, what fluid should I be using?

Thanks v much for any help.

have you checked the gearbox torque mount?

These are notorious for causing clonks and apart from being relatively cheap ( about £30 ) are also very easy to change in about 20 minutes.

Ignore everything in this video prior to 4.00 minutes in at which point he shows torque mount. No special tools are needed it's simply 4 bolts .

+ YouTube Video

Yes, the rubber in it was shot. Sorry thats what i meant by lower engine mount. It didn't improve the situation unfortunately.

Replacing the transmission fluid is no harm, particularly if the vehicle has 100k on it & it hasn't been done before. I'd recommend doing that regardless of whether it solves your clunking issue or not being honest. If it solves the issue, that's a bonus. If not, at least your transmission has fresh fluid to keep the parts lubricated :)

Have you checked the suspension front and rear? Trailing arm bushings, or propshaft joints/bushings, control arms? Any play in these can cause a clunk noise.

The XC90 kept using JWS3309 transmission fluid up until 2014, but some other Volvo models used JWS3324 or AW-1 (Equivalent spec, just a different name) with the TF80 gearbox around the 2011 mark. There's a bit of confusion with regards to the right gearbox oil to use around this time, so you could give the dealership a ring & give them your reg. I'm sure they'll confirm exactly which spec you need :)

Just a thought from a non expert, but have you tried switching to manual on this streach of road and forcing the box into one of other gear?

It you traverse this part of road forced in one gear, let's say 4th and no clunks, then sounds like could well be harsh gearbox change alone.

John l

Unfortunately the dealer had the car for quite a few weeks on multiple occasions and when the warranty expired said they can't solve it. They also don't give out part numbers as they said because then i can do it myself :confused_smile:

Vwry good idea. Should have thought ofbl it myself lol. Thanks will try tonight.

Tried this and NO thunk! So definitely a transmission issue? Next steps a flush?

In which case what is the best approach for a 2013 XC90?

Thx

Can anyone give pointers on what fluid i need and the correct method for the transmission fluid change?

Thanks

Do you have VIDA? You need it to set the transmission counter & its best practice to do it that way. Its possible to do a flush without the software, but you need to measure what fluid you take out & add the same amount back in. By resetting the transmission counter when the job is done, you’re effectively telling the car that its got new transmission fluid.

The XC90’s used JWS3309 up until 2014, whereas many other models changed to JWS3324 or AW-1 around 2011/2012. I’ve been recently advised that these fluids are interchangeable & have similar properties, so it doesn’t make much difference which one you use. However, check your owners manual & it should tell you the recommended fluid to use.

Have a look on YouTube for videos. Its a similar process on most models.