When installing a tranny cooler on a Ranger with an automatic transmission, does it matter which side of the cooler hooks up to the radiator or tranny. The tranny cooler mounts to the core support sideways, but I wasn't sure if the line from the radiator goes to the top or the one from the tranny. Anyone know for sure if it matters.........I look at it as just an open flow so I didn't think it matters, but I want to make sure. Thanks

 

I would perfer to have the oil hit the tranny cooler first and then the radiator cooler. With this setup the fluid will come up to a "normal" temperature in cold weather.

I don't recall which line is the out from the tranny, anyone??

 

Ken: Explain further for me. How does routing the fluid to the auxiliary cooler first ensure that the transmission fluid comes up to temp properly in cold weather?

 

No, route in through the radiator cooler first, then the tranny cooler. You will have no problem getting it up to operating temperature even in cold weather. You want the returning fluid to be as cool as possible, and the coldest it is going to get after going though the radiator is the coldest the radiator gets during operation, which is probably between 150 to 180. The transmission can use all the cooling it can get.

Also be advised that running a tranny cooler is no excuse to use the transmission recklessly. Don't go towing up hills in OD. It is much easier on the transmission and produces less heat to disable overdrive whenever you pull up a hill or into a strong headwind.

 

Thanks, Bear River. That's what I think about an aux transmission cooler, too, but always like to hear lots of opinions.

I also thought of it this way. Most aux transmission coolers sit in front of the A/C condenser. As a result, heat from the aux transmission cooler is blown onto the condenser, which reduces the condenser's cooling efficiency. I figure I want the transmission cooler in the radiator to pull as much heat as possible out of the fluid before the fluid moves on to the aux transmission cooler. That way, less heat from the aux transmission cooler is transferred to the condenser.

By the way, this whole O/D debate has me curious. Is it true that the torque converter is in lockup whenever the transmission is in overdrive? If so, how is it that overdrive is so evil when towing? I've heard answers ranging from "it produces more heat" to "O/D is the weakest (mechanically) gear". It seems to me that if the PCM detects that O/D is unsuitable for the current conditions, it automatically drops the transmission into the next lower gear.

If I'm driving up a hill, the transmission should do its job properly and drop out of O/D if it cannot sustain the load. I can see how shifting in and out of O/D constantly could be hard on the transmission; however, it seems to me that as long as the transmission isn't shifting in and out of O/D a lot, then I should just let the transmission do its job.

Does anyone really have an evidence showing that towing in O/D is a "bad" thing? Or, is it all just presumptive?

 

towing out of overdrive also keeps the gear engaged when you let of the gas, therefore allowing for more engine braking when towing.

Also note, though you may not hear anything out of the ordinary from your engine at the time, hauling loads at lower RPM puts strain on the main bearings and thrust bearing surface, shortening engine life. Basically when these fail to the average auto or truck driver the engine is blown.

If you are towing over 50% of your rated capacity, you really want your engine RPM to stay near it's high point of the powerband. My 4.0 Pushrod hums along nicely at 25-3000 RPM while towing 5,XXX lbs at highway speed. (58-63 mph for me, according to my speedo). And I have been figuring about 11 MPG doing so. My best MPG is around 18-19 tops. At those speeds, and engine RPM, I can actually set the cruise and not notice normal grade changes on the interstate. I know this is usually not advised, but it doesn't drop speed or force a downshift on any grade less than 4%. I usually know the routes I take well, so I know when to kick of the cruise for the steeper grades that are coming up.

I never see my temp guage move more than a smidgen up or down from it's "just under half" spot that it normally is. When i stop from 90 mins of highway driving, and let the truck idle to "cool down", I can touch the tranny cooler tube and its very warm to the bare hand touch. In the 90 degree heat memorial day weekend here, it was to hot to hold, but not to hot to just touch. My stainless Dunkin' Donuts coffee mug gets hotter.

 

The torque converter does not remained locked up all the time in OD, the torque converter will come unlocked under heavy throttle. The reason this is so destructive is that since the transmission is in overdrive, the gear ration is greater than 1:1 when one rotation of the engine results in more than one rotation of the driveshaft. This puts significant load on the torque converter. If it is locked up, you get no slippage within the torque converter. Actually slippage is an incorrect term, since the torque converter is actually like a bunch of fan blades. When on set of these blades turns, it forces the fluid to move, which in turn moves the other set of blades. This transfers motion to the rest of the drivetrain. There is some heat generated within the fluid however, and the amount of heat that is generated is directly proportional to the difference in speed between the input side of the torque converter and the output side. When the torque converter is in lockup mode the blades are bypassed, and the clutches in the torque converter make physical contact. It is not unlike a maunat transmission clutch at that point. As a result, if everything is working properly, there is no speed difference between the input and output speeds of the torque converter. In the lower gears, the gear ratio is much lower, so the resistance that has to be overcome is much less, so the heat that is generated is also much lower than it would be in higher gears. In fact, on the A4LD, and its electronic versions, there is no lockup used in 1st and 2nd gears.

In overdrive, you will have to push the engine harder both because the gear ratios are higher, and also because the engine is operating below the powerband. If you tow in 3rd instead, the engine will rev higher, placing the rpms in the strongest part of the powerband. Also the gear ratios will be lower, decreasing the stress to the torque converter and engine. Since the engine doesn't have to work as hard, the the transmission is less likely to come out of lockup mode, since lockup status is most often governed by throttle position. Also since there is less stress on the torque converter, less heat will be generated if it does unlock.

A good tranny cooler will help the fluid last longer, and buy you more time to work with if you decide to pull loads with the torque converter unlocked, but even so, the heat from the torque converter while unlocked in OD can easily rise to the breakdown temperature of the fluid before it even reaches the cooler. In 3rd gear, the heat produced is significantly lower. You could tow as long as required with an unlocked torque converter in 3rd gear. The only limitation is cooling capacity.

I installed temperature strips in my lines in and out of the radiator, and the output line from the tranny registered a peak temperature of over 280 degrees farenheit at its peak. The way I drive, I leave in in OD for the level areas, or whenever I can maintain my speed in OD without unlocking. As soon as I detect it has unlocked, I downshift manually. So you can see that it doesn't take long for the heat to build up in the torque converter while in OD. The second strip located on the line between the radiator and my factory tranny cooler indicated a peak of 230. I am just in the process of hooking up my transmission temperature gauge. I located it just after the tranny cooler. This way, I can get a fairly accurate reading of the fluids temperature after it has passed through the coolers.

On the driving methods I use, I don't necessarily recommend them to everyone. I try to stay in OD for two major reasons. One, I am traveling at speeds between 75 - 85 mph on the rural highways. At these speeds, the engine is operating on the lower end of its sweet spot, between 2500 - 3000 rpm. As such, I can handle many of the lesser hills and grades without losing significant speed, and without the torque converter unlocked. The second reason is fuel economy. This is my second priority, since fuel economy is largely a wash while towing. But since gas is expensive, I try to use as little of it as I can. By keeping it in OD when I can, I reduce the fuel consumption somewhat. When I come to the steeper hills I try to maintain between 65 - 75 mph, and if I drop down to close to 65, or the torque converter comes unlocked, I promptly downshift. If the torque converter is not unlocked and I want to downshift, I just mash the throttle down to force it to come unlocked. I then downshift and let off the throttle a little bit to allow the torque converter to engage again. The reason I wait till it unlocks is because if I downshift under load with the torque converter locked, the downshift is is hard and jerky. If the torque converter is unlocked it is a very smooth transition.

 

As I understand it, the main concern about towing in OD is when you encounter conditions where the tranny is hunting between gears, causing the locking and unlocking of the torque convertor clutch. The back and forth between 4th gear and OD can generate above-normal heat which gets transfered to the ATF (by design). This is above and beyond the additional heat that the drivetrain is already generating on account of the increased load. The bottom line is that you may end up with ATF fluid that is breaking down under extreme heat, and a hotter-running tranny in general. Keeping in mind that the torque convertor clutch itself (among other things) is applied and released by virtue of fluid pressure, you can get an idea as to how things can start going downhill real quick and accelerating toward disaster once the tranny overheats and the fluid gets burnt.

Darn good reason to add a tranny cooler if you tow, IMO.

 

Bob, I have a factory installed tow package, with a aux tranny fluid cooler, in my 99 4.0L 5R55E tranny.

The hot fluid coming out of the 5R55E trannies lower connection point, flows to the TOP radiator connection, for precooling, then out the bottom radiator connection, over to the input side of the aux tranny fluid cooler, (which is mounted on the lower right front of the AC condenser), through it & back to the tranny via the return line & connecting to the TOP fitting point, on the 5R55E tranny.

Don't know what kind of cooler you are going to buy, or may have, but those with turbulence vanes in the cooler, to cause the fluid to mix & come in better contact with the coolers heat exchanging elements, MAY be sensitive to fluid flow direction.
So if your unsure what you have, check the coolers instalation instructions, or call the coolers manufacturer, about line hook-up!!!!

 

Great O/D discussion. It gives me some things to watch out for while I'm towing.

I'll be attempting to install a Hayden Rapid-Cool #678 plate & fin style transmission cooler (7 3/8" x 9 1/2" x 11" x 3/4"). www.haydenauto.com. This larger one isn't going to fit directly against the front of the condenser on my '97 since there's only about a 3/4" gap between the front of the condenser and the bodywork. I think I'm going to have to attach the transmission cooler to the front of that same bodywork and then protect it from debris with a cover. I plan to take pictures and do a write up when I'm done.

 

The ideal temp for auto trans is 170*. If you can keep it from 170* to 190*, it would be ideal. Regular transmission fluids breakdown rapidly in higher temps. Flow should be from bottom up. Honeycomb type coolers are the best. jd

 

Thats why I went with a B&M cooler. The plate style cooler has a lot of surface area, but is very thin and is not vulnerable to damage from debris. The heat exchange is excellent, though I won't know how good till I finish getting my gauge hooked up.

 

As promised, here's a link to the transmission cooler installation I did today: https://www.ford-trucks.com/forums/6...th-photos.html

 

Bet that tranny has a big ole grin about right now!!!!! lol

 

Feel the line after a drive the cooler line is the one you want to place the cooler in.
I recommend a trans temp gauge, I got the digital one from JC whitney it has a quick response time, So you can modify your driving habits quick!! You should see how fast the temps rise in the drive thru or at stop lights even not to mention towing uphill!!
A $50.00 gauge can save you a $500.00 repair bill(low side) So it is money well spent
even for non towing driving, Believe me you will take it when you buy a new vehicle kind of makes boring drive more fun guessing what the temp will be at the top of a hill!
A oil cooler is another good thing to have for towing that not many people get. If your going long distances it will help keep your oil in good shape and take some stress off the regular cooling system!! Always mount the incoming(hot) line on top and the cooled line on the bottom!! Heat rises so if the hot is on bottom it will eventually conduct the heat to the top and won't cool as well. A good thing to hqave also is a infra red thermometer, You can check the temp on everything trans, engine, rear end!!
tires, Wheel bearings, that chick in the mustang!!JK!! On a multi axle trailer if you have one tire that is hotter than the others it could be it is low on air or the axle isn't in line with the others and scrubbing trying to turn, adding more strain to your vehicle!!