My tech did an automatic transmission service on our 1991 Volvo 245 today. By the looks of the pan gasket she’s of the opinion that the car might well never had have had its pan gasket changed, and perhaps not the filter, and perhaps not the fluid either.
She cleaned the bottom of the transmission somewhat, and put a large drain pan underneath the car. She removed the 14mm drain plug and drained most of the fluid. She removed the 18mm lower starter motor bolt that was holding the dipstick tube in position, and undid the 24mm nut holding the dipstick tube against the transmission pan.
She removed fourteen 10mm pan bolts, and the five 8mm bolts that held the filter on. Fair warning: removing the filter (more a strainer, really) caused another deluge of fluid – sideways to some extent. Next time we’ll take a knife and poke a hole in the filter, since we’re replacing it anyway. That way the fluid drains more predictably.
She inspected the magnets and saw much sludge, and some metal slivers (perhaps ¾” long). She cleaned the pan and magnet. Brake cleaner works well.
She installed the new filter. Due to its shape it’s impossible to install it the wrong way.
The pan gasket was not flat, so she first re-inserted the pan bolts into the gasket and pan, so as to hold the gasket in place. The smaller size of the bolt holes in the gasket make this viable. She moved the pan-and-bolts-and-gasket assembly into position and started threading and then gently torquing the bolts.
She reattached the dipstick and starter motor bolts, and poured about ¾ of a gallon’s worth of Dexron/Mercon down the dipstick — what the manual recommends, and also approximately as much as had come out when draining.
We went for a test drive – perfect behavior.
After that, with the engine and transmission at operating temperature, she stopped the car, moved the shifter through its various positions, waited two minutes, and with the engine running, checked the fluid level again, topping up as needed.