As detailed in my GMC Safari Thread I recently replaced the valve body in the transmission with a rebuilt unit. This seems to have fixed the torque converter lockup and accompanying harsh shifting issue. A friend of a friend who is a GM tech recommended having the fluid flushed after I swapped the valve body. The fluid that I drained out was fairly dark, and I have no records as to when it was last replaced. I replaced the filter and re-filled with 5 qts of clean fluid, but there was another 3 or so quarts in the torque converter.
I have heard varying opinions on flushing fluid in old transmissions. Some say that the new fluid can loosen old deposits that will float around causing havoc. The passages on the old valve body look to be clean though, and obviously the new valve body has no deposits in it. I am also considering just changing the fluid a few times over the next month as a "poor man's flush".
Thoughts from the hive mind? Thanks!
I've done a 3x drain and fill (with torque convertor lockup in between drains) a few times in our Honda Odyssey. You could just drain and refill during the next few oil changes. I'm following the "drain with an oil change" schedule on my friend's 99 Camry. Is there a filter that you can change in the transmission on the final drain?
Yes, there is a filter under the pan.
This is the way that I do a transmission flush.
First drain the fluid from the pan, Remove the pan and change the filter where applicable.
Next put the pan back on, And fill the transmission fluid to the high mark on the dipstick, but do not start the engine.
Now remove the trans cooler lines from the radiator and drop them into a clean pan. Now start the engine and let it idle while it pumps all the dirty fluid out of the torque converter. When you see fresh fluid coming out of the trans cooler line shut off the engine and reconnect the hoses.
Lastly add more transmission fluid Until level is correct.
I've been doing it this way on cars and industrial vehicles for years and haven't had a problem. I've never done a "power flush" I could see how that could cause problems in some circumstances.
This. Couldn't have said it better.
HappyAndy wrote:
This is the way that I do a transmission flush.
First drain the fluid from the pan, Remove the pan and change the filter where applicable.
Next put the pan back on, And fill the transmission fluid to the high mark on the dipstick, but do not start the engine.
Now remove the trans cooler lines from the radiator and drop them into a clean pan. Now start the engine and let it idle while it pumps all the dirty fluid out of the torque converter. When you see fresh fluid coming out of the trans cooler line shut off the engine and reconnect the hoses.
Lastly add more transmission fluid Until level is correct.
I've been doing it this way on cars and industrial vehicles for years and haven't had a problem. I've never done a "power flush" I could see how that could cause problems in some circumstances.
If it isn't really bad(smells burnt, no longer red, etc) just do another drain/fill, or invest in a vacuum fluid extractor, those things kick ass.
HappyAndy wrote:
This is the way that I do a transmission flush.
Can you still remove the converter drain plug, or is that option gone on newer vehicles?
In reply to pjbgravely:
I still think converter drain plugs are some sort of myth, like metric degree wheels, buckets of propwash, 68 beetle water pumps, etc.
HappyAndy wrote:
This is the way that I do a transmission flush.
First drain the fluid from the pan, Remove the pan and change the filter where applicable.
Next put the pan back on, And fill the transmission fluid to the high mark on the dipstick, but do not start the engine.
Now remove the trans cooler lines from the radiator and drop them into a clean pan. Now start the engine and let it idle while it pumps all the dirty fluid out of the torque converter. When you see fresh fluid coming out of the trans cooler line shut off the engine and reconnect the hoses.
Lastly add more transmission fluid Until level is correct.
I've been doing it this way on cars and industrial vehicles for years and haven't had a problem. I've never done a "power flush" I could see how that could cause problems in some circumstances.
as it is time to change the fluid on the Disco's trans.. I will look into this
In reply to Kenny_McCormic:
I drained a converter with the drain plug on a Mustang foxbody 4Cy so they did exist. After that I swore never to work on an automatic again so I have no knowledge of the newer ones.
