Secondary Aux Transmission Cooler

[bobmannel]

I have a 2005 Explorer with 4.6 V8 and towing package. No transmission servicing has ever been done and I have owned this vehicle since new. I have 80,000 miles on it.

Recently I was pulling a car on an open trailer up a grade that was probably about 2 miles long at 6% grade. I consider it the most significant climb of my trip up I-81 into Christiansburg, VA. The trailer is probably about 1,800 pounds and car was probably about 3,200, so combined weight was probably around 5,000 pounds. I was driving in normal mode (OD on), the outside temperature was about 40°F, and it was nighttime. My speed was about 55 mph. The engine was pulling hard, transmission had automatically kicked down to a lower grade and I was probably taching about 3,000 rpm, maybe a little more. Engine temp gauge was rock soild at its normal position between 1/4 and 1/2 gauge deflection. In the past, I have been towing loads up steeper grades between 50-55 mph at higher outside tempatures, but with weights more around 4,000 total.

I was surprised that on this particular climb, nearing the top of the grade I observed what looked like smoke curling out the back, illuminated by the headlights from behind. I pulled over thinking that the transmission front pump seal had let loose as this had happened to me long ago on a C4 transmission in an early Fairlane. Sure enough, transmission fluid was all over the underside of the Explorer, dripping on the hot exhaust and onto the pavement. I was probably stopped for about 15 minutes when I decided to see if I could go a few more miles to get within 100 miles of home where AAA could rescue me. As I started out again, keeping the speed between 45 and 50, I kept checking for vaporized fluid in the headlights from behind, but did not see any. The transmission was shifting fine, so I kept trying to get closer and closer to home. Three hours later I made it. The next morning there was only a very small amount of fluid on the ground.

I took the Explorer into the Ford dealership and was told that my description sounded like the transmission had overheated the fluid and spilled it out the vent. However, I had no codes for overheat, no codes to indicate anything was wrong. The mechanic said there was no indication that the front seal had leaked. He determined that I had lost about 1½ quarts of transmission fluid.

He did a transmission flush, put in 12 new quarts of fluid, and replaced the thermostat and flushed the engine coolant system for good measure.

I plan to install a Scangauge II to monitor the transmission fluid temperatures (TFT), but that might only help me manage the temperature, not solve the problem. I have considered adding a second transmission cooler. There seems to be space above the existing one to install an identical second cooler. However, my concern is covering up more of the radiator and possibly causing increased potential for engine overheat under these steep grade climbs while towing.

Has anyone encountered the problem I mentioned and found the solution was a second cooler, in spite of the significant size of the stock OEM cooler? If so, anyone install a second OEM cooler above the existing one?

 

[fusseli]

Welcome to the forum.

Sorry i don't have any real help for your problem. Perhaps it is as simple as some kind of overflow valve discharging hot tranny fluid while tilted up a grade, then the remnants you found was just excess dripping off. My only reaction would be: why tow with O/D off, especially with a sizeable load. Pretty sure that's unrelated to your issue though.

 

[bobmannel]

Ever since I have bought my Explorer, I have towed thoughtlessly because I have a V8 and tow package. I figured Ford knew best. Until now. I did not expect trouble with such cold outside temperatures, relatively low speed, and normal temperature on the engine coolant. Ford had my complete confidence. Now I have ordered a Scangauge to monitor fluid temperatures and will tow up the really long steep grades out of OD and maybe lower gears and slower speeds. But, when the engine can pull, it's a shame to be unable to tap into it. If an extra trans cooler will allow me to gain back my confidence, I will do it, but I don't particularly like putting more coolers in front of the radiator and there is not a lot of room in the engine compatment for other locations.

 

[wood1]

Greetings and welcome to the site!

Many guys, myself included, have added a second cooler beside their OEM one. Some have also added motorcycle sized pusher fans in front of them too, very nice. Search it and you will see the threads.

It is considered common knowledge to not tow any amount of weight in OD especially in hilly areas. It increases the strain on the tranny, tow in D only unless your trailer is very light.

Lastly, the temp gauge is a good addition. At least you can then watch what's going on. Seems like you got away with it this time.

 

[bobmannel]

What Explorer do you have, what second cooler did you use, and where did you put it? My big concern is blocking more of the radiator. The Explorer is supposed to suspend A/C operation if the coolant temp gets too high, which would give cool air to about two-thirds the radiator, with the other one-third still running through the trans cooler first and being heated. If I install a second cooler above it, I feel I am reducing the radiator efficiency in steep grade climbs, even when not towing. I am wondering of anyone has seen this kind of problem with adding a second cooler in front of the radiator.

 

[Ronin8002]

Why not just help fight the heat issue by increasing the fluid capacity of the transmission? I bought one of these a while back and am about to get around to installing it:

http://www.summitracing.com/parts/PMA-PA27455

They also make a model with a dipstick to make fluid drain/fill easier.

 

[wood1]

He's right, whenever you increase the volume of the transmission fluid you decrease the temperature. I have a '93 (1st Generation) 4.0L V6, with a 4 speed OD auto transmission (A4LD). I added the second cooler beside my first and it is in series with the first. There has been some discussion that the "best" way would be to have two connected in parallel, I would replace them both in that case with two the same size to ensure good flow to them both. I also have an external filter set-up that I made from hydraulic parts from Princess Auto.

If you are afraid of increased engine temps from blocking airflow I wouldn't be. This is not an uncommon modification. You can add Water Wetter to your coolant, tow with your AC off... you already have an electric fan don't you? I do not think your engine temp will get too high but that's just my opinion.

I don't think you can hurt a 4.6 that way anyway, I once ran one without the lower rad hose connected for 20 minutes at highway speed, half the cylinders shut off to keep it from killing itself. The Ford tech shrugged and told me I wouldn't hurt it that way. He thought it was funny that the throttle position was 100% during that time though...

 

[wood1]

Here is Aldive's thread where he installed an extra filter and cooler. There is a lot of good info here. The cooler should have unrestricted airflow. It does not necessarily need to be in front of the rad.

http://www.explorerforum.com/forums/showthread.php?t=127283&highlight=tranny+filter+relocation

 

[The Electrician]

I suggest either Ford OEM Transmission 4-rows Oil Cooler # 9L3Z-7A095-A
DORMAN #918204

or Ford OEM HD Transmission 6-rows Oil Cooler # 7L1Z-7A095-B

 

[bobmannel]

I picked up a second OEM cooler. I will probably T the lines to the first to run the second in parallel. I guess if I wanted to get fancy, I could put in a shutoff valve to disable flow through the second one. That way I could use it just for towing.

Seems in this day and age with all the bells and whistles they put on vehicles, they could have put in a regulator with a big cooler for towing packages. The regulator could work like a thermostat to keep the fluid temperature at optimum. Buy, heh, what do I know!!

 

[Joe in NY]

I picked up a second OEM cooler. I will probably T the lines to the first to run the second in parallel. I guess if I wanted to get fancy, I could put in a shutoff valve to disable flow through the second one. That way I could use it just for towing.

Seems in this day and age with all the bells and whistles they put on vehicles, they could have put in a regulator with a big cooler for towing packages. The regulator could work like a thermostat to keep the fluid temperature at optimum. Buy, heh, what do I know!!

I know this thread died long ago...

But for those who come across it, these transmissions actually do have built in thermostats for the fluid. So Ford actually did try the larger cooler with a thermostat. If you look up and compare an Explorer cooler to others, you will find that the Explorer cooler is SIGNIFICANTLY bigger than an Expedition and F150 cooler. Explorers coolers are best compared to an F250! Ours are 14 Row coolers but not extremely wide. An F250 cooler is only 10 rows but wider. So basically Explorers have a cooler that is considered by Ford to be "adequate" for an F250. BUT, some idiot approved the location to be behind the AC Condenser! This kills the effectiveness tremendously.

Just some info for you readers!

 

[Drewmcg]

You can monitor your trans temp with a cheap bluetooth (or wifi) OBDII scanner and program on your android or iphone. At least I think so. I've tracked mine on a Bosch OBDII wired scanner--my '02 XLS has a transmission PID (actually, two) for trans temp.