: Bbob - Tranny Oil Cooler Line Quest.

06-12-04, 02:48 PM
I know that you have stated that the factory radiator tranny oil cooler is perfectly adequet for all normal usage, but being a "belt and suspenders type" I want to add a small oil-to-air cooler in series with the factory cooler. I've done this type installation on several previous vehicles, but I've run into two areas on my '03 Deville DTS that perhaps you can help me with. First, can you tell me if the return line to the transmission is the upper or lower hose connection on the radiator end tank ( on drivers side of car)? Second, the upper hard connection to the radiator tank fitting seems to be some type of plug-in quick-connect coupling (with a small spring ring on the fitting screwed into the radiator and covered with a movable plastic shield). Is there some type of special tool needed to disconnect this line, or does it just pull out of the fitting, after removing the bracket that supports the line? I tried to remove the portion of the upper fitting that's threaded into the radiator fitting, but it only seems to loosen about 3/4 to 1 turn and then stops, so I did not to force it. The quick-connect seems to be o-ringed. Any guidance you can offer will save me a lot of trial and error. Thanks so much. John.

06-13-04, 04:11 PM
the connector you are talking about is made by jiffy-tite. you can release the clip without the tool but i strongly reccomend against it. GM uses the same connectors on oil cooler lines on trucks and i've seen them blow off after radiator replacement weeks later. the tool is available though jiffy-tite.com i bought the set from my local snap-on dealer expensive but worth the money

the release tools are also available online separately. they are made by snyder manufacturing, and are of high quality

06-13-04, 04:14 PM
also if you have removed the clip without the tool REPLACE THE CLIP. cheap insurance. available through jiffy-tite.com or your local GM dealer

06-14-04, 12:07 AM
Why not cut the line in another spot , flare it, and tap into it with your new cooler lines?

06-14-04, 11:38 AM
Actually, from a cooling standpoint, you can put the aux cooler in either of the lines. It won't make a difference if the conditions are harsh and the system is cooling to it's maximum capacity.

Sometimes it is nice to have the aux cooler in the feed line from the trans as in cold weather the radiator will always warm the trans oil going to the cooler after the aux cooler so that it warms up quicker and doesn't run too cool in cold weather.

In hot weather, if the aux cooler is really performing, it will cool the trans oil before the rad cooler if it is in the feed line to the rad and reduce the cooling load on the radiator.

06-14-04, 12:30 PM
Bbob, never quite thought of it that way -- makes a lot of sense for a really hot climate like SC, where it's consistently in the upper 90's during much of the summer. (And the traffic in Myrtle Beach in murder because of the visitors).
Tapping into the bottom connection on the radiator will be much easier too, since it is a standard compression fitting and not a "jiffy-tite" quick connect, like the upper fitting. To satisfy my own curiosity though, is the lower line the supply from the tranny or the return? John