Trans Oil Cooler Lines

2002 Grand Caravan Sport, 3.3L, 2wd. I am having trouble locating the lines to flush the ATF. In my Hanes it shows "Transmission Oil Cooler Nipples" on the drivers side of the Radiater, one on the top and one on the bottom but no lines going to them. It also shows "Auxilery Transmission Oil Cooler Lines" on the other side of the Radiater but Im pretty sure that would be for an external additional cooler, right? I only see two lines coming from anywhere on the transmission that could be them. They are on the top of the Transmission, side by side, and run to the driver side of the Radiater wrapped in a plastic netting like thread. But they are rubber and I was expecting some type of steel lines? If those are the lines how would I trace to know which one is the return. I cannot see where they connect to the Radiater because they run behind a piece of plastic. Please Help

Anyone? Does the Transmission have a seperate Radiater?

The fitting closest to the engine, on the transmission, is the return line. Just unhook the rubber line from trans and dump it in a bucket:)

Thought it was the other one. Thank You Very Much. I will do it this weekend.

Sometimes, it good to put a line on the case fitting also. Just in case documentation is wrong:) Any 5/16" line will work for temp use. It could get a little messy otherwise... Have fun.

Thanks for the correct advice Rex. I flushed it today. Measured my 5 gallon bucket in quarts and got 3 for 3, I ran 12 through. Nice and clean, unlike working on my explorer....No ATF showers tonight. Thanks Again

Have a 99 GC 3.8L also trying to flush my cooler. Traced 2 rubber hoses that lead to the cooler but not sure which is the return line the top one or the bottom one.
I use the factory service manual on alldatadiy.com. Doesn't say which one is the return line. Can anyone help? Thanks.
Also is there anyway I can back flush the cooler to see what's in it without using a back flushing tool?

Im not sure if your 99' 3.8 is anywhere the same as my 02' 3.3, and I do not know anything about back flushing. Sorry. However I found it much easier to take the line off of the Transmission rather than hooking a new line up to the cooler. On my 3.3, the Tranny cooler lines are on the drivers side of the engine compartment directly on top of the tranny. They are two rubber lines with a plastic like netting around them. They run sided by side into the transmission and the return line was the line closest to the engine. I just put it up on ramps, pulled back the netting, slid the clamp down with a pair of plyers, and pulled the return line off by hand. I had a 5 gallon bucket under the van that I pointed the return into that I marked in Quart increments so I knew exactly how much to add. The pressure decreased alot after 3 quarts at a time so I figured that was safe. I had my wife start it up while I watched the line and I had her quickly run through all of the gears each time to get everything moving in the tranny. Hope that helps sorry I dont know anything about the 3.8.

If you are still going to go the route from the cooler end, on my Ford Explorer the bottom line is the Return on the cooler, and from what I here that it usually is. If you have to guess I would guess the bottom. If you get the wrong line alls you will miss is the fluid in the cooler......

Have a 99 GC 3.8L also trying to flush my cooler. Traced 2 rubber hoses that lead to the cooler but not sure which is the return line the top one or the bottom one.
I use the factory service manual on alldatadiy.com. Doesn't say which one is the return line. Can anyone help? Thanks.
Also is there anyway I can back flush the cooler to see what's in it without using a back flushing tool?


The best way to see "whats in the cooler" is to drop the transmission pan. Then, you could cut open the filter to see whats in it. Theres really no reason for cutting a filter or examining flush particles unless you really need to know whats in it. Like a paticular part failing in a transmission, or reasons for a repeat failure after an overhaul of the transmission. Don't get too caught up over the "backflush" marketing thats used. It sounds cool and all. But its not rocket science to get 90%-95% of the old fluid out, safely.