downshift transmission clunk!!

jeremypowell · Post by **jeremypowell** » 22 Jun 2009, 23:42

when ascending a grade in my v70 xc my car will clunk when it downshifts from 4th to 3rd gear. the car seems to upshift smoothly in every gear otherwise and is almost unnoticable in the flats(when overtaking and it downshifts from 4th to 3rd). this seems like more than a software issue which was the suggestion my local mechanic gave. to start he wants to flush $350, and reflash the trannys computer $???. has anyone experienced a similar problem or have any suggestions. thanks!

jeremypowell · Post by **jeremypowell** » 22 Jun 2009, 23:51

by the way, the car has 114k. if this helps or yields and relevance to the response.

Post by **FlyingVolvo** » 23 Jun 2009, 08:10

I have the same car; I wouldn't do a full flush from your mechanic. And he probably has no idea what he's doing with a "reflash".

Check the fluid first and note the level and condition. If you don't know how to check the fluid: Start the car, without driving and your foot ON the brake go through each position on the shifter all the way down and back to Park holding it in each spot for a few seconds. Then leave the engine ON in PARK and go check the fluid. It's the yellow dipstick under the air intake tube going to the air filter. Just remove the tube to have easier access. Wipe off the stick once with a clean lint-free rag, then insert for a second and pull back up for the fluid level.

It should be between the two marks for cold (assuming you do this first thing in the morning). The fluid color should be bright clear pink. If it is dark (or even black

) you need to do some drain and fills immediatley. A full flush (or "power flush" like some shops do) can be bad if the fluid is nasty; dislodging gunk and murdering the tranny.

There is a drain plug under the car where you can drop the fluid partially and refill it. It will drop about 3.5 quarts, put the plug back on, pour new fluid (3.5 quarts, or however much comes out) in THROUGH the dipstick tube (for this you need a longer funnel). Drive around for a while or so, I waited 50 miles, then do another. Then do one more so you've at least done 3 drain and fills.

These transmissions are very solid but the one thing they hate is bad fluid. I highly recommend Mobil 1 Synthetic ATF. It's a little pricer than regular Dex III but it should hold up to much more stress and heat. Hopefully this will clear it up for you. Let us know if you need any other help.

jeremypowell · Post by **jeremypowell** » 23 Jun 2009, 08:42

he's one of the highest recommended independent volvo specialist in the area so the trans reflash shouldn't be a problem. as for the flush i raised the same question about dislodging gunk and he said his machine doesn't force oil through like some. it merely ''replaces'' the oil cooler in the flow sequence..so as old fluid comes out new fluid goes in. i am wondering about the mobil one idea though. he told me that volvo shows my car to be a non-synthetic unit...should i go with that and just use volvo oe trans fluid? ..one clue i guess to the original fluid is the dipstick pull. if it is just flat on the top it is synthetic; whereas, if it has a hole for you to put your finger through, it takes conventional? thanks for the help

Post by **FlyingVolvo** » 23 Jun 2009, 08:58

I've never heard of the dipstick indicating fluid type. You should have no problems with synthetic fluid. I've been running M1 Synthetic for many months now with no issues (2000 V70XC with 127,000 miles). I had previously had some black/burned regular ATF from a Jiffy Lube years ago (bad!!!). I did a few drain and fills with no issues. My feeling is that like synthetic motor oil, changing a bit at a time will let the synthetic fluid clean up gunk deposits.

If you want to do a flush, do it yourself!

There are plenty of good write-ups on this forum and others on the procedure. It would actually be more or less the same thing your mechanic wants to do: Drain fluid, ass new, pump old fluid out w/ car running by pulling the line that goes from the cooler.

Keep in mind though... if all the fluid being changed and tranny re-flashed (I'd still wait for additional input from others before doing this though) still doesn't help the clunk, you may have a problem beyond these simple fixes. =(

jeremypowell · Post by **jeremypowell** » 23 Jun 2009, 09:23

yeah, i was hesitant buying this car because it was an automatic, my first. i'm told the stick version of this car is difficult to find because the nearest source was canada. i'm hoping these simple fixes will help..but i fear the worst. and to make things worse, my friends keep telling me i should've bought a subaru

volvomileage · Post by **volvomileage** » 23 Jun 2009, 17:59

i wouldnt trade a volvo for a subaru though....

subarus are good cars but maintenance is high..volvos are pretty bulletproof and buit like tanks...

just a hunch but maybe the clunking is caused by bad gear changes to a certain extent...such as hard shifting which can be also electronics related but i wont hurt changing the oil and having it professionaly cheked..

cheers !

jeremypowell · Post by **jeremypowell** » 26 Jun 2009, 12:59

fluid swap and reflash seemed to fix the problem. thanks all for the input and advice. since the fluid was way dirtier than i thought, i'm guessing that the clutch was not able to grab properly and that caused the shudder under load. it now grabs smoothly. i bought the fluid for my car from volvo and did two drain and fills; only 4 qts each time so i'll probably do another two in a couple of weeks. what a rip off the dealership is..i had a buddy who owns a shop buy it for me for the discount and he still paid 40 bucks a gallon. they would've charged me 80 per!!! i don't get it..it says dexron III right on the volvo bottle. next time i'll just go fully mobil 1 synthetic in another 30k or so. how many drain and fill cycles would y'all think it'd require to fully swap fluid from conv. to syn. ? i'm thinking at least 4? thanks again

volvomileage · Post by **volvomileage** » 26 Jun 2009, 15:55

hi...

i did 4 flushs and fill to change out the max from dexron iii to dexron vi semi synth but i used to get 3.5 liters max out of every flush...drove 50 miles flush and so on..shifts great

cheers !

Post by **Ozark Lee** » 26 Jun 2009, 20:10

It sounds like we have another satisfied customer.

...Lee