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Old 08-04-2018, 09:50 AM   #4
shorod
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Re: Did I correctly flush my transmission

You didn't mention if you had the engine running and the transmission in gear while you did this. Without the engine running and transmission in gear the pump is not pumping the fluid through the transmission so you are not circulating fresh fluid through the torque converter, transmission cooler and lines, etc. So what you did, while better than just a fluid change, is not equivalent to a flush. However, since you have a drain plug and apparently don't mind buying A LOT of transmission fluid, you'd be better served to just top the fluid level back off, drive the vehicle for 50 miles or so, drain again, change the filter, top back off with fresh fluid, then drive another 50 or so miles, drain and refill. That will cause you to dilute any of the old fluid enough that you have mostly fresh fluid and also keep enough particulates in the fluid that you shouldn't have slipping issues.


There have been reports of folks actually having worse transmission performance after a fluid flush than when they took it in for the flush because the transmission was relying on some of the particulates in the old fluid to properly engage the clutches. Modern transmissions update their logic to based on how much fluid pressure is required to prevent clutch slip, so if those parameters are not reset after the flush, the transmission behavior is abnormal.


-Rod
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