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Help with Auto-Transmission Flush

I was flushing the automatic transmission fluid on my 2006 Scion Xa, and I ran into a bit of trouble.
I drained the pan and replaced the tranny filter and then filled it back up.
I then unplugged the cooling lines from the radiator and turned on the engine to pump the old fluid out of the system.
As the engine was running, the oil stopped coming out. I stopped the engine, poured my last qt. of fluid into the pan and turned the engine on again.
Same thing happened, where it started spraying out the old stuff again, but then it stopped.
I left the engine running for a few seconds before turing it off.
I realize now that I was not giving the engine enough tranny fluid, but what do I do now?
Are there pockets of air in the tranny because I wasn’t giving it enough fluid?
How do I go about filling up those pockets of air (if there are any)?
Can I just keep filling up the pan until the new fluid starts coming out of the cooling line?
Did I mess everything up?
Thanks :ooo:

You should not have flushed it. It might be damaged. About all you can to is refill it, drive a short distance, and then refill again. Continue until the transmission remains full. Be careful if it won’t move. You may need to get it towed. In the future, just drain and refill every 30,000 miles. If you want to get all the fluid out, drain and refill 3 times with a short drive between refill/drain cycles.

I sincerely doubt you damaged the tranny. Yeah, the 30K drain and refill is the way to go for DIYers.

When I’ve helped friends with this process before, it’s much easier as a three-person job: one person to watch the fluid coming out and tell the second person the rate at which to add fluid, and a third person to turn the car off when the process is done. I agree with everyone else, though, that the drain-and-fill is pretty foolproof. The little bit of old fluid left in the tranny won’t hurt anything.

My major concern is the hydraulic pump that ran dry. It is probably OK if it was only running dry for a few seconds. Fill the transmission, shift it through the gears and check the fluid level. Take the car for a short drive and check it again.

My concern would also be how long it ran dry. Most automatics have very few bearings in them and use bushings. Bushings do not take well to lack of lubrication. A few seconds is one thing; a few minutes or more is quite another.

No, you didn’t mess anything up. When you drain the transmission quite a bit of old oil stays in the torque converter. That’s the dirty oil you see when you pump it out through the cooler lines. As long as you stop the engine when you see a mix of air and oil coming out there will be enough residual oil in the pump to prevent any damage. As for air pockets, that doesn’t occur in transmissions like it does in engine cooling systems.

Just refill it like the others have said and you’ll be fine. I’ve used that method myself with never a problem.

Standard procedure after repairing a transmission after its re-installation is to fill the pan and then start the engine. Then, as the fluid leaves the pan and circulates you can continue filling the pan, occasionally putting the transmission in gear but not letting the wheels turn. Cycle from Park to Drive to Reverse, etc.

During this entire process absolutely nothing is rotating in the transmission except the torque converter in its bushing in the front pump, and the pump itself.

Obviously, you don’t run the thing without fluid any longer than necessary, but you HAVE to run it while it’s low on fluid while you’re filling it. If you just try to fill it until it’s full before running it, they usually just vomit the fluid back out because of air pockets.

Bottom line: fill it, cycle it through all the gears, check it and make sure it’s full, then stop. You’re done.

Are there any drivability symptoms or noises that developed from all this? Or are you just checking here for advice before proceeding to the next step of re-filling the transmission? If the latter, while I’ve never done it that way myself, I doubt any problem has resulted, provided all this happened during idling in the driveway; i.e. you didn’t drive it with low transmission fluid.

I’ve never disconnected the transmission/radiator lines myself. When I’ve done this, the only thing I do is drop & clean the pan, check for metal filings, clean or replace the filter, put the pan back on with a new gasket, and refill. The refill process can take some time I admit, I’ll add, check, idle, check, shift a bit, check, drive a little, etc until the level stabilizes at the dipstick mark. I like to slowly approach the mark from below, as going over makes for a messy job to correct.