Hey Everyone. I have some questions on tranny temps. I know there has been alot of posts on this, but my questions still linger. Therefore, I am posting my questions. From what I can tell, 225 is max sustained tranny temp. You can go up to 250, but not more than a half hour.

So here is the deal. I tow a 10k trailer and take it up some logging roads. They are pretty steep grades for about 10 miles. My tranny usually gets close to 250 going up them. I have tried everything to get my temps down, but nothing seems to work. I usually go up in 4 low, but it doesn't help. The fastest you can go is 5 mph, so you can't get much airflow. My tranny is a BD with the BD torque converter. I have a HUGE seperate tranny cooler with it's own electronic fan on it. That helped, but I still get really close to the 250 and the clime usually takes about 40 minutes.

Does anyone have any ideas on how to get the tranny temps down?

Any help is appreciated. Thanks much!

 

That's hot. I wonder if you could put a switch to turn your fan on and stay on for the climb. That may pull more air into the cooler.

 

Subscribing. I hit 225 and was really concerned.

 

You are going to burn up your transmission with those temps. Something is not working right if you have a 'huge' tranny cooler 'with it's own fan'. I have been told to remove your 7.3 trans cooler as it will restrict your flow if you install a 6.0 (goes by the radiator and the truck fan pulls air throught it) trans cooler. Where is this 'huge tranny cooler' installed? Something is not right with this set up. Your temps should be 50+ degrees lower..... or you have a new or rebuilt tranny in your future.

 

Out of curiosity, at what temp does the electric trans cooler fan come on? Where is your sensor located? Have you compared your trans gauge to the internal PCM sensor to see if it's calibrated correctly? Where is your cooler mounted? (Mounting it dead center of your radiator helps the fan clutch engage sooner) Are you hearing the clutch fan engage?

10 miles in 40 minutes is closer to 15 mph, but there still wouldn't be much airflow so it sounds like you really need the fans to work correctly. Why is your speed so limited? Is it a really tight road where you can't safely travel any faster?

Lastly, when I hear "logging road" then I imagine a road that is sometimes quite muddy so you would really have to stay on top of your maintenance to keep the radiators clean. A little bit of mud will restrict airflow quite a bit. Just throwing ideas out there. I hope you find a solution soon.

 

TC unlocked, high load, low speed... Not much you can do about it.

If you use 4low and get the RPM's up, you could throw a manual TC lock up switch on it and that would help, just have to remember to turn it off.

 

I have to agree with Joe. Do you have the cooler in the radiator also?
Make sure the cooler bypass is not stuck open.

 

'99s were built without a transmission cooler in the radiator. Some had it added later. Does your truck have one? If not, you really need it. That will lower your temperatures quite a bit.

Did the "huge" cooler replace the stock cooler? Is it a stacked plate or is it one tube that goes back and forth across the cooler?

 

TC lock button would be the best thing. What size is the trans cooler? It will take one heck of a cooler to keep the temps down if the TC is unlocked and tugging that much weight. Envisioning 3 stacked in a box, car size radiators in the bed of your truck. With a power fan, Maybe a inverter to run the 1/2hp 110v fan/blower.

 

How about one of these babies ? Claim lower temp 20 to 50 degrees. But you will have lower air flow at 5 to 15mph. Derale Transmission Pan Cooler for Ford E4OD, 4R100, 5R110 and 5R110W Derale Transmission Coolers D14208

 

No ammount of coolers with no air moving across them will cool a 4r100 tugging 10k-15k at 5-10 MPH...

With the TC unlocked all that thing is doing is building heat. Only way around that is to get the RPM's up around 1500-1800 and lock the TC.

DO NOT keep the TC locked at lower RPM's or the pump can not move enough fluid to keep the TC locked properly and you will have more issues.

Mark knows more then I could ever hope to guess about these trannys, but doing what your doing... TC lock, 4low and higher RPM's are the only way you will keep the heat at bay.

 

I don't believe the claims. That's from their webpage. The part they are leaving out is that the air under the truck is usually hotter than you want the transmission. There is heat dumped from the radiator and from the exhaust system. How can you cool the transmission with hot air? It doesn't make any sense.

If you want to cool the transmission use a cooler, not a pan.

The best way to cool this is to keep the cooler in the radiator and replace the other cooler with a cooler from a 6.0L truck.

 

Sorry to be so slow on the reply. So I will try to address some of the questions below. First, the logging road is very windy, requiring the speeds I am traveling on it. It isn't very muddy, so plugged coolers are not the issue. As for the cooler, I am running the BD Aux cooler (BD Power - Product: Auxiliary Cooler). It is mounted up under my bed and it is run inline with the factory 7.3 cooler up on the radiator. I thought the two coolers, one with an electric fan, would do the job of keeping things cool. Thinking about it now, could the extra lines I have run between the two cooler be causing the problems? If memory serves me correctly, the fan comes on around 200 degrees. I easily could add a switch to keep the fan running, but I don't know. I just know I need to keep the temps down.

So is it true that temps up to 250 not sustained is ok for the tranny? I don't like to ever see it over 210, but it gets to that pretty quick.

Also, one thing I left out is I have a bd oil pan on my tranny as well (BD Power - Product: Transmission Pan). I would think my tranny should run very cool with this set up, so I must be missing something.

 

Here is what it says on this page:
You call HUGE? I call it tiny. I found one place that shows that the 6.0L cooler is 23"x17.5"x1.25"

It isn't clear if the BD cooler is a stacked plate or a tube/fin design. It says 16 pass, does the cooler have one tube that goes back and forth 16 times, or are there 16 separate tubes going from one side to the other? Coolers are designed both ways.

The size for the 6.0L cooler I showed above is for a 31 row cooler. Almost twice as many rows.

Alright, they probably are not plugged with mud. How about leaves and grass? Or anything else? I've seen plenty of coolers that were covered with enough junk that air couldn't pass over them and none of that junk looked like mud.

Yes, that could be causing the problem. The 4R100 has a pressure bypass. If the pressure in the cooler lines gets too high from a restriction the bypass opens to keep lube flow to the rear of the trans. If the bypass wasn't there the trans would burn up from lack of lube.

That pan looks cool. In my opinion that's the only "cool" a pan has. The pan does almost nothing to cool a transmission. There isn't enough flow at the pan surface (on the inside) to efficiently transfer heat to the pan itself. Then the air under the truck is WAY too hot to transfer heat when the truck is working hard, especially when moving slow. Have you ever stood next to the driver's door right after your climb? Does the air coming from under the truck feel hot or cold?

In my opinion, and remember it's only worth what you paid me for it, the way to cool your truck is to remove the cooler under the bed. Run the cooler line from the front of the trans to the radiator cooler, then to a 6.0L cooler, then back to the rear of the trans. Installing the fan from your current cooler on the 6.0L cooler will help, too. But that's just my opinion.

 

Totally agree!

Get a 6.0 cooler, Car-Part.com--Used Auto Parts Market, is a great resource for them and it will help. The 6.0 cooler is huge, almost the same size as the radiator on my wife's mercury mariner. Other than that keep the RPMs up and you should be ok.