I call this "the scrunch". Comes from that action of pushing against the floorboards and firewall with one's feet while getting comfortable in the seat. Usually the pressure is up and to the right, thus the top right corner of the seat frame moves.

Couple of things can happen. Most common, as mentioned previously, the weld in the top corner of the frame breaks. When I rebuild seats, I put a reinforcement corner in there and weld it in.

I have found on several occasions that the scrunch causes one side of the seat adjuster to jump a tooth after years of scrunching. While this usually cannot be fixed without disassembling the adjuster sides, which join in the center with a tube, and moving the right side up a notch; I have on several occasions been able to get just the right side to jump a notch by putting a board against the seatback, reclining in the back seat and pushing it forward with both feet. A little brutal, but it has worked!

DS

My '89 245 has @275K and a similar driver's seat condition. On mine it's neither the foam nor broken seat pipes. I haven't looked closely but it appears to be that the hinge stop on the right has worn so that back will recline more on that side. I anticipate a nut/bolt type solution.

It's a common problem.

Question: can you see the tubing on the bad side pushing against the Cloth or does the tilted side still feel like the foam is there?

Try to figure whether it's the very typical Foam tare or the frame breaking away or loosening from the bottom.

There are 4 13mm nuts to take off and the seat comes right out of the car.

Look for these Nuts slightly above the slide rail that is mounted to the car.

Look under your seat from the backseat of the car. Right where the heat duct is there should be a wire, pull it until you see the white connector...disconnect that first.

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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

It might be some loose bolts in the frame, this happened to me. Take the seat out and look at it. Dan

I had the same thing on my 89. It was that way when I got it. The problem is that the top of the seat frame is held together with nothing more than a couple of small spot welds, which can break loose.

The simplest cure is to replace the entire seat, if you can find one with matching upholstery. Otherwise, you can use any seat from an 86 or later 240, from either side, to get the parts you will need. You will have to remove the seat back from the bottom part, disassemble it down to the bare frame, and reconstruct it using the better of the two foam cushions (which you may need to repair/reinforce) and your original outer cover. You can also repair the adjustable lumbar support at this time if it is not working properly. It is not that difficult of a job---perhaps the hardest part is dealing with the "hog rings" that clip the edges of the upholstery to the seat frame and each other. You can either twist them open with two pairs of pliers and reuse them or simply cut them off and replace them with plastic zip ties. Getiing the backrest angle adjusting knob off can be tricky too. It looks like one piece of plastic but is actually an outer knob with a round trim piece in the center, which has to be pried out to reveal the spring clip that holds the knob to the mechanism. Practice on the donor seat before doing the one you are going to keep.

I think your seat foam is broken . The seat back looks tilted in such a situation. You can rebuild a seat.Try this site and this link.
http://home.no.net/ebrox/Tony1.htm
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DD-1990 240 DL SW M47II FI 3.1 220 K miles Turbo Sways,Custom headlight circuit ,Insulated roof,Tinted Glass,

its pipes in the frame of the seat that`s broken, you can weld it together again just pull the seat out of the car and take of cover and foam.
this is a common problem with 240:s seats.

Claes
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V70 2,5T -98