Transmission was clunking bad - how (I hope) I fixed it.

[micahdsmith]

I have owned my 2004 Volvo XC since July, 2011. 168 000 km when I bought it. It seemed to run well, but 2 months later the transmission started lunk and kalunking. Especially after getting hot and bothered, it would be wretched - I was just waiting for it to fall out behind me on the road.

I read everything I could in this forum that I could find without spending too much time searching. I had it checked out at the local Volvo dealership. Transmission is shot they said, 6000$ (cdn) to replace it.

I changed the transmission fluid. Instantly smoother. For 3-4 days. Then it started coming back, so I changed the fluid again - it had gotten dark again, so I must have not gotten everything loose. I tried translube this time, and did two cycles after some driving to make sure I got it all out. Great. Smooth, until 6-7 days later.

I looked at the servo body replacement. That doesn't seem like a ludicrous gamble to me ... but it is more than I can do in my garage likely ...

I read more, remember that the lunking is often due to pressure. Luckily, I'm working more on wishes than knowledge. Pressure you say eh? I can tell you about pressure. The fuel filter on this thing looks like maybe it is 170 000 km old. (not likely, but it sure looked old). So I changed it. 10 minutes.

Instantly the transmission was better, not great though. But better. 3 days later, and it's MUCH better. I'd say really good. There's a noticeable lurch going from D to R. But nothing like it was before. Back when it was bad, you could shift R to D or back, count quickly to 4, and then feel the big blang.

I used to get flares too - 2-3 mostly. Revs up, car decels, then clunk. Or on decel quickly into a corner - la-klunk. My forum reading put those on a different troubleshooting sketch than the massive clunks I got R to D. Monster Clunks.

All gone. Thank you 10 minute fuel filter job.

(the only question of course, how long will it last?)

[howardc64]

Fuel filter as in the filter for the gas coming from the tank beneath the passenger rear door?

Don't know how that would make the transmission shift better. Would be a mystery if it did.

Might check your lower transmission torque mount, the small bushing is likely busted and your shifts might improve with it replaced.

[micahdsmith]

I did the lower transmission mount and the upper mount (big one) back in October.

Did the fuel filter last Sunday. (rear passenger door). Nothing else done that day. Shifted better out of the gate, and then improved more so.

I realize that the fuel filter shouldn't fix the transmission. But as far as observable science goes - I can't pin the seriously different transmission performance on anything else - I didn't do anything else. And the improvement was immediate.

The difference is stunning.

It is either the freakiest coincidence, or the transmission needs a steady unimpeded fuel supply to the engine for it to do it's work.

I'll come back and post tomorrow after the transmission falls out and this was just a calm before it dropped - we can all have a good laugh at newbs who think changing the fuel filter does anything for the transmission.

[Astro14]

Coincidence. Logic states that correlation is not causality...I doubt that the fuel filter changed anything. If it was clunking during "garage" shifts (P-R-N-D) then it has issues, could be a couple of loose mounts, but it sure wasn't the fuel filter...

[howardc64]

I did the lower transmission mount and the upper mount (big one) back in October.

Did the fuel filter last Sunday. (rear passenger door). Nothing else done that day. Shifted better out of the gate, and then improved more so.

I realize that the fuel filter shouldn't fix the transmission. But as far as observable science goes - I can't pin the seriously different transmission performance on anything else - I didn't do anything else. And the improvement was immediate.

The difference is stunning.

It is either the freakiest coincidence, or the transmission needs a steady unimpeded fuel supply to the engine for it to do it's work.

I'll come back and post tomorrow after the transmission falls out and this was just a calm before it dropped - we can all have a good laugh at newbs who think changing the fuel filter does anything for the transmission.

I don't doubt you... we've certainly been through learning mysteries on this car since 2001.

Was battery disconnected? I wouldn't think so for fuel filter.

If you still have the old fuel filter... might do a 10min reinstall to confirm your observation :)

[micahdsmith]

Did not disconnect battery.

Garage shifts were less than before mount change in October, but still quite bad - especially after getting the engine warmed on a drive. But all shifts were bad. Now, after warming up on a drive, no noticeable change in shifting.

I should totally reinstall the old filter. I am wishing I didn't just chuck it after draining -- maybe it hasn't gone out yet.

Certainly a single correlation does not imply causality. But it can sure mess with your head if you're there to observe it. Now if only it were reproducible ...

Correlation is how we learn many things in life. I don't touch pots on the stove because I've experience them as hot before when in that position.

Other possible explanations - going up on the ramps under the front tires, and the jack in the rear with an axle stand under the rear axle twisted the car sufficiently to alter the transmission's alignment so that now it works better than it did before.

Or, it was going up or down the ramps that did it.

Correlation cannot prove causality. I'm not claiming the fuel filter fixed the transmission. But it sucked going up on the ramps, and it was good afterwards.

I think I've given all my evidence, as it were - unless I can find the old filter.

[howardc64]

and the jack in the rear with an axle stand under the rear axle twisted the car sufficiently to alter the transmission's alignment so that now it works better than it did before.


How did you jack up the rear? This car obvious has no rear live (solid) axle to put the jack stands on. There are drive axles in the rear but you don't want to put any jack stands on that (not sure if you can even get to it). The only place to put a jack is on the jack points under the rear door or liftpad platform just in front of the wheel wells. And where did you put the jack stands? Not sure how this would change how the car shifts. Just wondering how you jacked it up and where did you put the jack stands.

I do get the impression there are a ton of electronic data that goes to the transmission computer. If fuel filter was indeed the cause of change... it'd be cool to figure out the causality. But certainly, we are all stumped :)

[micahdsmith]

I drove it up onto the ramps. I then put the jack under the rear passenger door (front of it) where the jack fits on. That lifted the back enough without dislodging the front - though the jack was very close to car centre.

The jack stand I put under what looked like a very solid frame attached part between the rear wheels, stand more on the passenger side than driver side. Rear wheels may not even have been lifted fully clear of the ground. Probably should have been more careful on jacking/standing [4 points instead of 3], and not sure what part I put the stand under! Now I'm just imagining part X collapsing on top of the stand and car tipping to passenger side where the fuel filter mechanic fumbles with a wrench.

[jda2000]

mica,

don't reinstall the old filter, please. The car is shifting fine so enjoy it. Do cut open the old filter to see how it's inside.

Remember, positive thinking is a powerful thing:p

[jkochis]

I have owned my 2004 Volvo XC since July, 2011. 168 000 km when I bought it. It seemed to run well, but 2 months later the transmission started lunk and kalunking. Especially after getting hot and bothered, it would be wretched - I was just waiting for it to fall out behind me on the road.

I read everything I could in this forum that I could find without spending too much time searching. I had it checked out at the local Volvo dealership. Transmission is shot they said, 6000$ (cdn) to replace it.

I changed the transmission fluid. Instantly smoother. For 3-4 days. Then it started coming back, so I changed the fluid again - it had gotten dark again, so I must have not gotten everything loose. I tried translube this time, and did two cycles after some driving to make sure I got it all out. Great. Smooth, until 6-7 days later.

I looked at the servo body replacement. That doesn't seem like a ludicrous gamble to me ... but it is more than I can do in my garage likely ...

I read more, remember that the lunking is often due to pressure. Luckily, I'm working more on wishes than knowledge. Pressure you say eh? I can tell you about pressure. The fuel filter on this thing looks like maybe it is 170 000 km old. (not likely, but it sure looked old). So I changed it. 10 minutes.

Instantly the transmission was better, not great though. But better. 3 days later, and it's MUCH better. I'd say really good. There's a noticeable lurch going from D to R. But nothing like it was before. Back when it was bad, you could shift R to D or back, count quickly to 4, and then feel the big blang.

I used to get flares too - 2-3 mostly. Revs up, car decels, then clunk. Or on decel quickly into a corner - la-klunk. My forum reading put those on a different troubleshooting sketch than the massive clunks I got R to D. Monster Clunks.

All gone. Thank you 10 minute fuel filter job.

(the only question of course, how long will it last?)

I also own a 2004 XC70, I had a flare issue when it was new, after long trips when trans was most likely very hot. VADIS sw upgrade fixed. Make sure your car has all the latest sw updates.

[sjonnie]

I read more, remember that the lunking is often due to pressure. Luckily, I'm working more on wishes than knowledge. Pressure you say eh? I can tell you about pressure. The fuel filter on this thing looks like maybe it is 170 000 km old. (not likely, but it sure looked old). So I changed it. 10 minutes.

Instantly the transmission was better, not great though. But better. 3 days later, and it's MUCH better. I'd say really good. There's a noticeable lurch going from D to R. But nothing like it was before. Back when it was bad, you could shift R to D or back, count quickly to 4, and then feel the big blang.

Lol!

[handyandy]

I had been having the odd shift problem on my 01 and by changing the brand of fuel it cleared it right up, Guess with the engine not running 100% the shift can be off.

:D

[kamiar]

I had been having the odd shift problem on my 01 and by changing the brand of fuel it cleared it right up, Guess with the engine not running 100% the shift can be off.

:D

Are you serious? if yes, let everyone know what brand did you switch from and to.

[Brown Dog]

I have a weird one too.. I had been buying gas at Sheetz consistently because it was so convenient, well a couple weeks back I stopped and got some BP ultimate premium and almost immediately my car started running better. It had more power and the transmission was shifting like new! Just a random thing? I have noticed that when my car is shifting smooth and working properly my idle is smooth as glass. But on those days of a slightly rough idle it shifts crazy and feels like a shudder when cruising at 35-40 almost like its bogging the engine down.
I dont know what the variables are to make this happen but I am trying to figure it out.

Maybe fuel pressure having an effect on engine power has some connection to transmission shifts.

[Astro14]

Cheap gas making a car run bad? Yeah...sounds about right...keep in mind too that the use of premium is recommended, lots of people use regular, but I am not among them. My car has no driveability issues....

[handyandy]

Are you serious? if yes, let everyone know what brand did you switch from and to.

I had been using CO-OP fuel in XC and a 350 chev and both started to run odd switch over to ESSO or Shell and once both had run through couple tanks both ran 100% again Even the other half noticed the difference so must be good.[thumbup]

PS just ordered up a fuel filter based on this post.

[passleft]

I was being cheap when working a crap job and while unemployed. I didn't notice too much issue on short drives, but did notice that the transmission seemed to be noticeably shifting oddly with a bit of a clunk. I took a few longer drives and was shocked at how horrible it was. I stopped at Sunoco and filled up with 93 and it was an instant difference. Wawa & QuickCheck out here started selling cheap gas, and it's just that.

I changed my fuel filter a few weeks ago and it was like I bought a new engine (and subsequently the transmission). Before this, even using good gas I was getting a noticeable turbo lag and transmission lag to go with it.

My boss at work owns an almost identical 2004 XC70 that he bought brand new. He's always used regular gas (87) and says he has no problems. I tried a few tanks of regular to see if the computer would re-calculate itself, but the engine just acts more and more sluggish. I have 170K+ on my 2004 and he has 55k. I'd say there's definitely a computer reactive correlation between the gas the the way the car acts, including the transmission.

[sjonnie]

I'd say there's definitely a computer reactive correlation between the gas [and] the way the car acts, including the transmission.

To paraphrase a pair of well known car mechanics. Booooooogus! :eek:

[drnukeit]

I just bought a 2001 XC V70 with 168,000+ miles. I havr noticed a similar issue on mine. I upgraded the gas to plus or 89 octane and i saw an improvement. I am filling up with 91 octane tomorrow and replacing the fuel filter this weekend. I will let you know if there is more improvement.