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Question on changing trans fluid

O

openheaders

New Member
I'm close to being able to fire up my Mustang for the first time in 13 years. :vic The engine is new, but the C4 trans has been sitting in the car this whole time. I plan to change the filter & top it off with fresh ATF before I fire it up. But what about the rest of the fluid in the converter? As I understand it, you're suppose to pre-fill a converter & can't simply drain /replace all the fluid while it's in the car. If that's true, how can I go about changing all of the fluid? Is this something I should even be concerned about?
 
Most (not all) torque converters have drain plugs that can be accessed via the inspection plate. When you see the drain plug you will realize it will not drain all the fluid from the converter... so it is not as if you will be starting up with a dry converter after you drain the old fluid. Personally I would not be concerned about a little old fluid left in the converter if the fluid was just old and not burnt.

If you are really concerned you can unhook the return line from the transmission cooler and run it until you see new/clean fluid coming out.

Running the engine with the transmission in park under low fluid conditions for short periods is not going to harm anything...

Good luck,
-Rory
 
im not a fan of changing fluid in an old trans unless it has been rebuilt. i would just top it off if low and leave it alone. check for an old thread on vintage-mustang about this subject and judge for yourself. wes
 
You only need type F if the trans hasn't been rebuilt recently. According to several local shops, the rebuild kits have been intended for modern Dex/Merc ATF for ~25 years. Heck, Type F won't hurt anything, even if it's not called for....B&M sells it as performance fluid. :lol
 
"gotstang" said:
You only need type F if the trans hasn't been rebuilt recently. According to several local shops, the rebuild kits have been intended for modern Dex/Merc ATF for ~25 years. Heck, Type F won't hurt anything, even if it's not called for....B&M sells it as performance fluid. :lol
Click to expand...

That's what I used when I had to replace fluid, B&M Trick Shift. On the label, it says it 'meets or exceeds type F requirements'.
 
Recently changed the fluid and filter on my ’65 C4. It seemed like I got more fluid from the torque converter drain plug than from the pan and filter. It took a total of 7+ quarts of Valvoline Type F for the refill.

Be careful during the refill if you choose to drain the converter. When refilling the fifth quart, fluid started pouring out of the trans vent pipe on the driver’s side of the transmission. If I change it again, I will know to add about 4 quarts or so, start the engine, and pour in the rest while checking the level periodically.
 
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