The transmission in our original 1997 S90 started to "whine" under acceleration at a bit over 100k miles and a check of the transmission fluid revealed a bit of the burned smell. A check with several local mechanics had a worn torque convertor mentioned as likely cause, as there were cosmetic and other issues with the car we simply drove it carefully figuring to swap transmissions only if we had to. At 135k miles, the engine went and we found another low mileage car when the wife didn't want to drive anything other than a 960/S90.

Our "newer" 1998 S90 (by 5 months) purchased in 2013 now has a bit over 60k miles and I'm getting a transmission whine again. It started appearing only after a warm start (stopped at store for a short time, etc.) and it would fade after a couple of miles. However, it is becoming more apparent during all operation, although still louder right after a warm start. In this case, the transmission fluid smells just fine and I did a flush just in case that might help.

Any thoughts on doings something now vs waiting until the issue forces a repair? It is my wife's car for only local driving, about 6k miles per year. We are simply not hitting the accelerator very hard right now, which does not impact the wife's driving style very much.

 

The only transmission issues that I have ever heard of with those cars was when the radiator went bad and mixed coolant with the trans fluid. I think a few drain and fills will do it good. Maybe you should take it once per week and take it on the highway.

 

I'll probably do a full flush when I get some time, I did the drain, fill and drive a couple of times when we acquired the car in 2013. My rough calculation is that about 80% of the fluid is now new, with no change in performance. It is a pain in the ^&%$ to get the fluid level just right on the S90, I have a burned spot on my arm from getting to the trans dipstick back in 2013. I certainly wish Volvo had put in a slightly longer trans dipstick!

My only hesitation on the full flush (I don't have the equipment to connect to the radiator lines) is that two friends had that done (one Volvo, one other marque) and both ended up worse than when they started. At least I rarely screw stuff up, as an old aircraft / race car mechanic.

 

Hey Bob,

I have been thinking about flushing my gearbox. I'm going to save the old fluid in case it makes the gearbox worse.

This item fits the radiator: 6 x 16 1 5mm Inverted Flare An Fitting Metric | eBay
(-6 to 16-1.5mm-inverted-flare adapter)

With an additional -6 to push-on-hose adapter you can cleanly connect a piece of tubing.