A whining, turbine sound is a common characteristic of a failing Volvo (or any) transmission. This occurs when the transmission is starved of trans fluid.
MVS Contributor Precopster has a 2001 V70 T5 (a turbo) and guess what? Whining sound, no forward or reverse.
Here Mike (Precopster) details his efforts to avoid replacing the transmission by draining the trans fluid (was black) and unblocking the transmission filter. It’s a monster thread with lots of good DIY transmission info and experiences.
Car is 2001 V70 T5 has about 130K miles and has a blocked transmission filter. Car won’t go forward or backward. The characteristic sound of a turbine from the transmission tells me the transmission pump is not getting fluid. There are no offered alternatives other than to get the transmission replaced or rebuilt with these symptoms. Many posters here have given up on their Volvos because of this exact symptom. Can we reverse the blockage at the filter? In this article I’ll examine how I tried (and hopefully succeed) in achieving this
PLAN OF ATTACK
1) Yesterday I replaced all the fluid by dropping 3.5 litres then using Gibbons method to drain about another 6 litres while refilling at 2 litre increments. This took about 2 hours because it was often just a trickle and sometimes was not pumping at all
I was using clear hose to drain and I could see that the fluid was struggling to get up the hose and into my container marked at 2 litres. Fluid was filthy black at first.
2) PHASE ONE, ESTABLISHING THAT THERE IS A BLOCKAGE
Blew compressed air back through the cooler through the hose and managed to get normal pressures back to the drain hose. I had UNBLOCKED THE FILTER!! Temporarily unblocked I might add. FINALLY the turbine-like noise was gone and wheels were turning with force in both Drive and Reverse while up on stands. Left it up on stands with engine running for another 30 minutes. No strange whining noise present. Wheels were still turning with great strength against the brakes in Drive. Took it for a quick spin and was great. After a longer drive (2kms) the noise re-appeared and the car slowed to a crawl. The filter had blocked again
Looking at this teardown video of a AW55-51SN out of a Nissan Maxima, I would say after you have your hole drilled you would then back flush it with compressed air at the radiator connection like you’ve already done. The junk that’s repeatedly plugging it would push out the hole with the fluid where you could catch it with a pan.
Without pulling the transmission from the car to separate the bell housing this might be the only ‘method’ that might actually work. You’d need a junk trans to inspect/partially take apart to determine exactly where and how deep to drill the hole. It would probably also be useful to see a new filter to determine whether you need to also make a hole through the lowest bit of the plastic filter in case the junk is getting trapped inside and has to resist gravity to push up and out. You could make a larger threaded hole in the transmission–say M17 in the main transmission housing and a smaller hole- M12 or 13 in the filter plastic so that you could install a plug on the filter before reinstalling the larger bolt into the main housing. It might take several rounds of backflushing, or devise some method for pushing fluid through instead of compressed air.