to flush tranny or not to flush that is the question

[dedrums]

have a 92 740 wagon it has 167 on it now I realy dont know where it came from or who had it what kind of maintanance so i ask when i pull out the at dipstick the color of the tranny fluid is a dark color(dark brown almost black) do you guys think i should flush it or drop the pan will this mess with my tranny.again i dont even know if the owner before me even checked the oil thanks in advance for any advice

[shiloh51933]

I wouldn't flush just yet, I'd drain/fill and run her a little bit maybe a couple of days then repeat this process a couple of times. Especially since you have no clue concerning the maintenance of her, flushing the tranny could be potentially dangerous. I'd also add some Lucas tranny treatment, I use full synthetic tranny fluid, engine oil and Lucas synthetic treatments. Same thing goes with flushing the coolant system out on a used vehicle that you have no clue what previous owner has done as far as PM's, Good Wrenching!!

[JDS60R]

On that tranny you have to start with dropping the pan anyway. Replace the filter and gasket. ( I prefer rubber gasket over the cork type). Clean the magnets in the pan and then you can flush or refill.

Yesterday I did a 1999 V70 with 186000 miles on it. The trans fluid was basically black water. I did a flush using the trans pump and not letting it run dry. I installed high heat high strength magnet in the plug ( replacing the weak Volvo magnet) . I then let it run for 20 minutes. This allows all of the new fluid to circulate and the magnet to pick up any slag that the new fluid is cleaning.
I double checked the level and drove it most of yesterday ( 30 miles or so). It works great .

Some caution that this type of flush has caused them issues. I have spoken to a few folks who have had issues and I do believe they "did" have issues. What caused the issue remains a mystery. So - for safety sake I would replace the filter and gasket, add strong magnets that can take the heat and bear the fluid. The do a few drain and fills.

This way you assure the pump never runs dry. It is not a tremendous issue if the pump runs dry and then you shut it down. I get feedback from some that they let the pump run dry for several minutes to "make sure" they got the old fluid out. I think this is part of what the problems may be.

If it were in my garage you would get a full flush with a quality new gasket and filter along with some new strong magnets. I run 1.5 times the amount left in the trans through it to fully flush the unit.

[edelmatt]

Hi. I've got another thread started on the topic of changing the AT filter on a 1990 240.

I'm curious if you dropped the pan and how many gaskets you ended up replacing. I found 2 gaskets on the filter housing itself and one for the pan. The kit I bought only has one gasket for the filter.

Thanks
Matt