Transmission Clunk 98 S70 T5

Post by **jblackburn** » 27 Aug 2009, 12:34

Today while driving to work, I stopped at a stoplight after coming down a big, maybe 3/4-mile hill where I had my foot off the gas the entire time. Usually, the car stays around 1500 rpms just coasting down that hill; today I noticed out of the corner of my eye that it seemed like the car was around idle speed, but thought nothing of it - the guy in front of me kept tapping his brakes so I figured I usually go faster. When I got to turn at the light, I hit the gas pretty lightly, and my car revved to about 3500 freely like it was in neutral, and then JOLTED forward with a huge clunk, screeching the tires and almost slamming into the car in front of me. The effect was sort of like when you pop the clutch in a manual, only I have an automatic. Once this happened, it seemed to both downshift and upshift fine after this point the rest of the trip, even after stopping again on an incline. No flashing arrow, no check engine light...I had a front tire explode on me last week randomly while driving, but as far as I could tell (til now) it had no ill effects to the car itself.

I did a transmission flush (fill & drain method - twice) for some brown-ish fluid that was in the car about 4 months ago - as far as I know the car was well taken care of before I owned it, but I didn't want to chance flushing an old transmission that never had been before, and since then it seemed to shift more smoothly and downshift less frequently. I checked the fluid towards the beginning of this month and it was still perfectly red and filled to the right level; I'll check it again after work, but any ideas what could have happened? Is my transmission on its way out?

Post by **jblackburn** » 27 Aug 2009, 19:10

Well, the fluid still looks perfectly fine to me, and filled to the right level after I got home. My car didn't do anything strange again on the way home tonight, but after today I'm kinda nervous about the 600+ mile trip through the middle of nowhere I have coming up next weekend.

OH! Another thing I should mention, about a month ago, the engine just randomly shut off going down the same hill. It was raining and kinda cold that morning, and the RPM's dipped below 1, bounced back up, and then to 0 and the dashboard lit up. Popped it in neutral, and it started right back up as I was still rolling, and it hasn't happened again. Perhaps totally unrelated, but I thought it was odd for it to stall in Drive.

Soooo...Any takers?

Post by **wheelsup** » 27 Aug 2009, 21:38

It's falling out of gear and into neutral. Mine does the same thing when hot. There are apparently 4 solenoids in the tranny and one controls the fluid pressure, it is probably failing. You can try replacing the valve body or just get a new tranny. Or do what I've done for the past 3 years and live with it. If I hear a clunk I pop it into neutral, tap the throttle to around 1500 rpm and then slip it into drive as I take my foot off the gas. More RPM = more pressure. Sometimes I just pop it into neutral as I slow below 35 mph if I know I am stopping and tap the gas. Then put it into D once stopped. Then it won't clunk for a bit.

To keep the fluid cooler you could try going to a synthetic and/or putting an aftermarket tranny cooler on.

P.S. If you end up replacing the tranny yourself give me a shout! I haven't ever done it but would like to help someone out to learn

. I'm over by Capital off of 540.

Post by **jblackburn** » 28 Aug 2009, 09:03

Thank you for that bit of advice. It hasn't "clunked" again so to speak (yet), but it felt like it missed a beat between first and second this morning...kinda like it thought about shifting up, hesitated, then changed its mind and stayed in 1st, revving kinda high, and shifting directly to 3rd when I let off. It could have just been that it was still in "grumpy mode" in the morning where it tries to keep the RPM's higher to warm itself up faster.

Switching to synthetic sounds definitely sounds like it's worth a try - I read a discussion about the proper transmission fluids to use in the 2000 models, and I don't remember if the general consensus was whether or not it IS ok to use the Volvo synthetic ATF for the 5-speed V70 transmissions in the old 4-speed boxes.

I'll definitely let you know if I end up replacing it (REALLY hoping I don't have to!) - I actually live in VA now, but my family still lives around the Triangle area, and my dad will probably help me with such a daunting task (hopefully it's much easier than my Honda was, where the transmission was a total PITA to get out of the car because EVERYTHING was in the way.)

Etheraldreamer · Post by **Etheraldreamer** » 11 Apr 2012, 16:14

Hate to resurrect this one from the dead, but I am having IDENTICAL issues, right down to the fact that it stalled out of no where before this started happening... was/is that related or just a coincidental redherring? I'll be doing ATF this weekend if I can. Thanks.

Post by **jblackburn** » 11 Apr 2012, 17:14

Did it choke out like it was in too high a gear, or just shut off?

Those transmission problems eventually traced back to a bad solenoid later down the road in my car, but the Mobil-1 fluid seemed to help for well over a year and 40K miles or something after that.

Post by **MoVolvos** » 11 Apr 2012, 17:35

Etheraldreamer wrote:Hate to resurrect this one from the dead, but I am having IDENTICAL issues, right down to the fact that it stalled out of no where before this started happening... was/is that related or just a coincidental redherring? I'll be doing ATF this weekend if I can. Thanks.

These discussions may be of further help.

https://www.matthewsvolvosite.com/forums ... 5&start=14

https://www.matthewsvolvosite.com/forums ... =1&t=47877

Heat is the main source of problem with transmissions leading to other issues. The second is the additive package which is in all oils engine or transmission.

Blessings,
BKM
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Etheraldreamer · Post by **Etheraldreamer** » 11 Apr 2012, 19:58

jblackburn wrote:Did it choke out like it was in too high a gear, or just shut off?

Those transmission problems eventually traced back to a bad solenoid later down the road in my car, but the Mobil-1 fluid seemed to help for well over a year and 40K miles or something after that.

I seriously just typed a well thought out and detailed response that took me like 30 minutes, went to click submit and my browser crashed... fml...

I will retype when I find the patience (most likely tomorrow) thanks for the quick replies all! More to follow.