Thread: Trans cooler lines, which is IN and which is OUT?

I have been searching all morning and I cant find this info.

The trans side is what I'm looking for.

Thank you.

The fitting that points straight DOWN is the outlet-hot fluid which needs to go into the cooler. The fitting that points horizontally into the trans-closest to the pan- is the return line which uses the cooled fluid to direct to lube passages in the geartrain.

I was hoping you would reply. Thanks for the info!

Next question. Is there any reason why I can't remove the stock lines from the fittings on the trans and go straight AN lines to and from the stock and aftermarket cooler?

It looks like 2 3/8 NPT fittings going into the trans. I know the stock cooler is 3/8 also.

Ahhh, we think alike Vinnie, but alas, as I believe Trannyman will confirm, there are check balls in those fittings on the transmission that have to be maintained. I too would like to do AN lines all the way but that put a damper in that idea.

Crap, they are on the tranny end of the stock lines?

Not in the stock line, in the fittings themselves where the stock lines connect to.

Thats exactly what I'm doing now

Unless a non-quick fitting trans is different.

My plan was to just use enough hard line to hook up an AN fitting to make it look like the AN fitting was connected somehow to the quick connect/disconnect fitting and then run it from there.

I just realized I put this in the wrong tranny section anyway

Well I didnt notice either, so dont feel bad. I'll move it over anyway.

Okay, moved over to the 4T65E section.

Only the feed side or fitting point straight down has a checkball and this is only on SOME 99 and ALL 00+ cases until early 04. 97-some 99 cases do not have the checkball. IF your case has a fitting with a checkball then it must be retained. These cases will have a larger thread on the feed side than the return side. There are fittings that accept the threaded cooler lines that do have the checkball and will work in a quick connect fittings' place.

This is honestly the biggest PITA project I have done so far. The lines on the radiator appear to be inverted flare and no one makes an adapter to AN that I can find. If you're doing this just get 4 3/8 hard line to AN fittings and go from there.

Done, not doing it again without that cheater tool for making AN lines. My finger tips hate me.

I only run one because of my higher stall torque converter and I tow every once in a great while.

My recommendation if anyone decides to do this is to just use a hard line to AN adapter, 3/8" to -6, on each side of the stock cooler lines and adapt you're aftermarket cooler with NPT to -6 fittings if you can.