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Transmission chatter when cold, but goes away when fully warm

I just recently swapped out my Automatic Transmission in my 91 MR2. The person i received it from had the system completely drained, including the torque converter. I found this out kinda hard the way, knowing that the pan was empty, but not expecting the torque converter to be empty as well.

After filling up the system, i thought i may have overfilled it, because the fluid level was reading above the hot mark on the dipstick. So i drained the fluid and replaced the transmission filter. I put in 3 quarts of fluid and added the 4th quart of fluid over time, mainly letting the car run and warm up to operating temp and then adding fluid and letting it settle. I kept doing this until i got to the full mark on hot.

So this is where im at now…

On a cold start, the transmission will chatter in all gears, from park to low. Give it about minute or so to start warming up the chattering slowly goes away. When its at operating temperature, there is no chattering at all in any of the gears, and it presumes to be normal and fine. It takes about 5 minutes to fully warm up to operating temperature. Should i worry about the chatter at the beginning while its warming up? i have to drive the car because i want to be sure that the transmission is okay. I have thought about adding an additive, but all that i have read is just bad results, and failed transmissions.

Any suggestions?

Don’t add any additives. This can make sense if the thing is obviously near death, and some people can report squeezing out a few more miles - but you just put it in there so I assume you’d like to get it working properly.

I also have to assume that the one you put in is used? What do you know about its history?

I also have to assume that you’re checking the fluid the right way - with the car hot & running & either in Park or Neutral. (The Park/Neutral difference matters and you’d have to check an owner’s manual to see what is correct for this car).

Other than that you’re going to need to clarify your description. “Chatter” isn’t a routine way to describe an AT issue. Furthermore I’m having trouble figuring out chatter while in park since park is out of gear. Go from relying on the word “chatter” to your best description of what is actually happening - what you feel & hear.

Yes the transmission is used, and has under 130k on it. The person that i picked it up from swapped out the transmission to convert it to a 5spd manual. He said that he had no problems with it at all and actually drove the car around as an automatic for a year. I trust the previous owners words as he is a part of owner of a specialty shop for MR2s directly and has a reputation to uphold.

I have been following the procedure on the full service manual, where i am to start in Park, shift through all the gears and then go back to Park to check the fluid level. The fluid level is supposed to be checked in park.

I took 2 videos of what is happening.

this video is on a cold start, where there is the noise that is through all of the gears.
I checked the fluid level right after i started the car, right after the video actually and it showed full on the cold side of dipstick.

This video was shot at operating temperature about 5-7 minutes after the first video was shot, and as you can tell, there is no sound at all going on until i rev it a bit in reverse. I checked the dipstick again, and it showed on the low side of full on the Hot range.

My only lead from here is to try replacing the ECU as it also controls the solenoids on the transmission as well, and this is almost identical to the problem that i had with my last transmission that ended up toasted.

I did drive the car around the block the other day and it drove and shifted flawlessly, through gears 1-3, i did not push it above 35mph as i was still in a residential area.
This is the best that i can describe my situation.

I can’t tell you exactly what that is - but its not internal to your transmission. Its something loose and/or bent out of shape or broken. It actually sounds like it could be a cracked exhaust manifold. There can make noise when cold and then quiet as they get warm because expansion seals the crack.

But it does sound rotational - like something on the engine hitting something as it spins - the two things on the outside spinning are the flexplate and an crankshaft pulley. I once had a noise something like that & turned out to be a loose flexplate bolt where the head of the bolt was backed out just enough to be in contact with the dust cover.

Right now you just need to find where the noise is coming from - because it isn’t in your transmission.

i thought it was the dust plate at first too, so i took it off and it still made the exact same amount of noise. I tightened all of my flexplate bolts as well just to be sure, and it still happened, with or without the dustplate in place.