: Seeking opinions on adding an external tranny cooler in addition to the radiator



jimsbox
10-28-10, 12:52 PM
Seeking opinions on adding an external tranny cooler in addition to the radiator. I am wondering if there is any inherent reason not to. Is it likely you could overcool the fluid and damage the tranny (4T80E).

Submariner409
10-28-10, 02:45 PM
Seeking opinions on adding an external tranny cooler in addition to the radiator. I am wondering if there is any inherent reason not to. Is it likely you could overcool the fluid and damage the tranny (4T80E).

Remember that the existing transmission cooler keeps the fluid at coolant return temperatures - way below 200 degrees but still warm enough to cook off condensation and oil vapor, and the fluid is not subjected to anything close to the damage that engine oil receives - one reason why transmission fluid easily goes 100,000 miles, no problem.

Unless you're setting up to drag race every weekend, pull a boat trailer or 3,000# camper, an extra cooler is not even close to necessary, especially in a DHS - the 3.11 final drive insures a calm, sedentary transmission speed on the highway.

jimsbox
10-28-10, 05:00 PM
Thanks Sub,

I agree, I am going to drop that idea.

Submariner409
10-28-10, 05:30 PM
Thanks Sub,

I agree, I am going to drop that idea.

.......here's one for ya': Cooling fans go to FAST at transmission fluid temps of about 302 degrees ! Figure that one out. If anyone in here would know why, it's JimD.

jimsbox
10-28-10, 05:58 PM
Sub,

Obviously the coolant won't be at 302 but the thinking may be to increase the efficiency of the radiator to draw more heat away from the transomission fluid.

Ranger
10-28-10, 09:02 PM
A 302 degree trans fluid passing through the radiator side tank will obviously transfer that heat to the coolant and cause the coolant temperature to increase and I would guess, pretty rapidly. I suspect that may be the reason, not to mention as Jim said above, I would guess that there is a limit to the temps they want to see in the trans and 302 might just be it.

tateos
11-03-10, 03:56 PM
I added an external transmission cooler when the original trans lost TCC lockup. I live in Phoenix where daytime highs are commonly 110+ in the summer, and with no TCC lockup, I'm sure there was some more heat being generated than expected when the trans was designed. Since that time, I have replaced the trans with one that has a TCC that works as designed, but I left the cooler on - I think it can't hurt in my climate.

I tried to fit a cooler on my wife's 2004 Grand Prix GTP, but couldn't find an easy/good way to route the hoses and mount the cooler, so I decided to pass. Trans fluid temps are displayed on the Driver Info Center, they are frequently in the 230-240 range in the summertime, and the fluid does turn to a reddish brown color, so I drop the pan and refill with fresh trans fluid every year or so. I've been using the Dexron III called for in the owners manual, and which I already had - maybe the Dexron VI would be better. She's gone only about 60K miles, but no trans problems so far.

republic
04-09-11, 12:43 AM
Greetings and apologies for posting on an old thread. I too have a failed TCC and although the transmission seems to work fine in my 2001 DeVille I was wondering about adding the external cooler to correct some of the overheating that the slipping creates.

Has anyone added a cooler like tateos did? If you are looking tateos, how long did you run the first transmission, do you think the cooler helped?

Regards

Republic

jimsbox
04-09-11, 12:56 AM
Click on Tateos (in blue letters) and you can send him a private message ( I think you may have to make 10 posts to the forum first)

00 Deville
04-09-11, 09:13 AM
Republic, If your worried about increased temperatures due to slippage you might want to consider changing from Dexron III to Dexron VI. The Dexron VI is synthetic and fully backwards compatible with Dexron III.

republic
04-09-11, 07:50 PM
Thank you both. The car drives flawlessly but has not been more than 400 miles from home since the code first occured. I am planning a trip to Arizona, about 1500 miles, and would really like to drive the DeVille. It is the most comfortable and economical in my fleet. I will look into the synthetic fluid. I had not considered that as an option. Again thanks and regards.

Submariner409
04-09-11, 07:58 PM
The "slipping" does NOT create extra heat in the transmission fluid. If the TCC is stuck off then the torque converter operates exactly like 95% of all other vehicles without a TCC feature. There is NO reason to add external coolers unless you intend to tow large trailer loads or race the car. The internal radiator cooler is perfectly adequate for the job, and the transmission is supposed to run at over 200 degrees in order to boil off contaminants and moisture in the fluid. The transmission fluid temperature alarm goes off at 304 degrees - yes - 304.

Change to the new (2006) DEXRON-VI fluid - it's now standard maintenance fill/exchange on all GM vehicles.

Ranger
04-09-11, 10:43 PM
:yeah:
The slippage will be minor and of no consequence.

republic
04-10-11, 08:19 PM
Thanks for the replies. I was just looking at maintenence receipts for the last trans service. 20K miles ago the garage (not GM) installed a filter and Dexron III along with a quart of Lucas transmission treatment. I believe their logic was that without the TCC woking properly the additive would get rid of slip. I've heard more bad than good about Lucas. I'll be changing the fluid (Dex VI) and filter this week. Can't imagine what crud will be in the pan.

00 Deville
04-10-11, 09:00 PM
I'll be changing the fluid (Dex VI) and filter this week.

Don't bother with the filter... it's only accessible during a transmission overhaul. Most parts counters will sell you something they call a filter... but it's only the 2 pick-up screens that are accessible when you drop the pan. There's no need to change these unless one of the screens is ripped... you'll see what I mean when you drop the pan... don't bother with a pan gasket either... it's reusable and very expensive.

http://www.cadillacforums.com/forums/attachments/cadillac-deville-1985-2005-including-1985/74366d1302411116-2000-deville-dhs-dexron-iii-vi-drain.jpg

The filter inlets is where the screens connect. Also pull the hidden drain plug to drain additional fluid.

republic
04-10-11, 09:28 PM
Appreciate that 00. I would not have known about the hidden drain.

Regards

00 Deville
04-10-11, 10:53 PM
Appreciate that 00. I would not have known about the hidden drain.

Regards

The hidden drain plug empty's the fluid in the side cover. The FSM states that you can change 11 of the 15 quarts by dropping the pan and draining the side cover. Let us know how much you actually get out... I was only able to get 8 quarts out when I did my 00 Deville.

Submariner409
04-11-11, 09:10 AM
Can't imagine what crud will be in the pan.

Use DEXRON-VI and DO NOT put any snake oil in the transmission.

Chances are good that there will be NO crud in the pan.

I just posted this somewhere else............transmission fluid amounts for the 4T80E...............

Bottom pan and side plug - ~11 quarts
Overhaul with original converter - ~12.6 quarts
Total overhaul, dry - ~15 quarts

Remember - this is a dry sump transmission - there should be NO FLUID on the stick with the engine off. Check the level with everything hot, idling in P.

republic
04-11-11, 10:17 PM
Thank you for the continued support. I will note how many quarts I replace.

Regards

republic
04-19-11, 12:01 AM
Drained the transmission tonight. I replace eight quarts. That puts the level to the middle of the 'HOT' section on the stick.

There was no sign of the Lucas additive the mechanic included on the last change but there were a few very small aluminum flakes and some glitter in the pan. Would appreciate your observations on these. Regards