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Transmission flush/check

1664 Views 1 Reply 2 Participants Last post by  ImperialCrown
I took the 727 Transmission (circa 1975) out with the motor. I know the transmission would move forward and reverse without hesitation but I could not check the upshifts as the car was not roadworthy. The transmission fluid was red and did not smell burned, however the pan had a lot of sludge in it. I ran a magnet thru the sludge and did not pickup any metal, so my first impression is that the Trans will be OK. I plan to flush out the trans and the convertor, replace the filter and gasket and put it back in... Is there any harm in hooking up air pressure to the cooling line inlet to the trans to flush out the old fluid and does it matter which line is the inlet and which is the outlet when flushing? Are there any bench tests that I can run to make sure the trans is OK before I put it back in?
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· Super Moderator
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
17,317 Posts
If the sludge material at the bottom of the pan is clutch lining, it still may need a rebuild sooner than later. If the transmission is already out of the car, now would be the time to address it.
You can use shop air pressure to see what pushes out of both ports. The outlet front fitting goes to the converter and the inlet rear fitting is lube to the rear carrier.
Use ~10 psi and a mineral spirit solvent if you plan on reverse-flushing the radiator cooler. With the valve body out, you can air test the clutches and bands with a rubber-tipped air gun. A hiss is a leak.
Service information and diagnosis is available here:
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