Overfilled Transmission

[Jon87V20]

So I'm not sure if my transmission is overfilled. I just installed the new TH400 with the deep dish pan, and a new torque converter. I started it up with about 5 quarts in there and I got it up to around 12 quarts before it started moving. Now, since I'm a noob, I thought I could run it with the rear driveshaft off while doing the initial filling and of course fluid started pouring out of the back of the transfer case when I put it in drive, so I shut it down quickly.

When I checked the transmission fluid level this morning when it was cold, it was reading up above "ok hot". So my dilema is, do I drain some out, or do I run a again for a while to make sure the cooler and torque converter are full etc. or will this damage the transmission?

I'd rather not drain a bunch out only to find that more needed to soak in other places.

FYI: It was running for about 15 to 20 minutes while I was filling it up and checking.

If I do need to drain some, I read someplace that you can remove the vacuum modulator and let it drain from there as the correct level is right at the modulator. Is this true, or BS?

Thanks!

[Irish_Alley]

first, the trans and transfer case do not share any fluid. when you had pour out was just out of the transfer case.

[Jon87V20]

Irish, yeah I know. I've since refilled the transfer case.

[Irish_Alley]

lol ok. but the proper way to check the fluid is drive it normally till reaching operating temp then turn off and let cool for 15 min then check while running. but 12 doesnt sound like too much. do you have a aux trans cooler was the Tc empty?

[Jon87V20]

Yeah the Converter was almost empty. I pre-loaded a quart before installing it. It has a cooler as well. I'm just worried it might damage it to drive it if it's overfilled. Do you think I'm ok to drive around the neighborhood a bit, and then check it, or should I drain some out first?

[Irish_Alley]

want to say no risk in that you overfilled it. its been a while but want to say a dry trans can take 11-12 quarts with a normal pan.

[Jon87V20]

Ok sounds good. I'll try taking it for a drive around the neighborhood for a few minutes, then check it again. Let's just say hypothetically, if it was too full, would it kill it if I used it just for a few minutes like that, or is it something that takes some mileage to hurt things?

[Irish_Alley]

depend on how much imo. a qt over wont hurt while 4 may. but dont take this as advice its just my opinion

[bd]

Overfilling can result in frothing of the fluid, which can cause the transmission to slip and overheat.  It can also cause the transmission to blow excess fluid out of the vent.  As little as one quart over can cause problems in some applications.  Bring the transmission to operating temperature.  Cycle through all of the gears and reverse several times.  Check the fluid level in park on a level surface with the engine running.  If the fluid level is greater than 1/4" above the FULL HOT mark, drain some fluid to drop the level into the proper range.

[Jon87V20]

Ok will do. Thanks, bd.