Transmission Fluid Temps...Help

[NCCamper2003]

Hi Gang, Here is the situation: I have a 95 XLT with 226,000, with 5L and 4r70w transmission (stock & original), with a 3:08 rear end. I just had installed a 21,900 GVW tranny cooler, a bypass filter, and a trans fluid temp guage. The guage sensor is attached to the output line from the tranny, before the cooler. My hope was that with the bigger cooler, I would see lower fluid temps. However, the highest temperature was 260* after 40 miles, 20 hwy followed by 20 in traffic. This scares me and now I wonder abou the accuracy of the guage, or is my tranny ready to fail? I do pull a small popup camper, and am looking to go to a larger one. But with these results, i am very concerned. As far as I know, I am not running syn trans fluid, so what is the breakdown temperature of Mercon ATF? What can you tell me about how to improve the situation? Help! The camping season is upon us. Thanks, John

[Bluegrass]

I have exstensive experience with this towing nearly 11,000 lbs gross combined weight.
I need you to tell how you have the extra cooling plumbed.
Are you going from trans thru the external cooler back to the trans or are you including the radiator in the loop?
Next, you will see these high temps at the output of the converter because this is where the fluid temp is the highest due to fluid shear when out of converter lockup.
I will give you more info in the next reply

[NCCamper2003]

Thanks for the info. I will let you know exactly how trans fluid cooling circuit is set up a little later when I find out. I have read extensively here about this, and there are obviously 2 very different points of view, based upon people's preferences, as one person has emphatically noted. To include the radiator the radiator or not seems to be a hot little topic!

Some observations from this morning: the ambient temp was 52*. I drove to work - about 17 miles in 45 MPH streets with little traffic. The last few miles are interstate - 55MPH. In 20 minutes, the trans fluid temp reached 200*, while at a long stoplight. Then I hopped on the interstate, got up to 60 MPH, and the temp guage fell to about 185* to 190*. As I pulled into the parking lot, the temp started to approach 200*. One more thing: yesterday, my coolant temp reached the high end of normal range (pointer under the "L" or normal) when driving on the interstate, then retreated to the "M" of normal. This leads me to believe, without talking to my mechanic, that the radiator may be included in the trans fluid cooling circuit.

It may mean nothing, but the ambient temp being 20* cooler than my first experience had that big of an impact?

BTW, before the first post (when the 260* was hit), OD and TCC lockup seemed to be operating normally. On flat interstate, at 70 MPH, the RPM was a little less than 1500.

Thanks for the help. ANy more info is welcomed!
John

[NCCamper2003]

Ok...it's confirmed. The radiator is still part of the trans cooling process. Now I am thinking the radiator most be clogged. In traffic, the engine runs cooler than when driving at interstate speeds. To me this means radiator and not thermostat. And I bet that the trans fluid is picking up heat rather than giving it off, when the engine reaches a certain temp. I think it's time to get the radiator rodded.

What do you think?

Thanks,
John

[Bluegrass]

Just as early comment, converter temps in the 190 range or higher while running in normal transportation use, not towing or hauling, is too high while running in converter lockup. While this temp is within the fluid heat abilty it leaves a less safe temp range under towing conditions.
Either the gage is not near correct or there is something else the cause.
I run in the range of 145 to 150 converter output as a normal range on longer non towing runs where the temp has a chance to normilize.
I do not use the radiator in the loop but use two external coolers eliminating the 200* radiator temps from the loop.
I also just recently installed a deep alum pan with it's own temp gage and now accumulating a temp record of performance over time to see trends.
Pan temps with my setup are running little over 125 for average non loaded performance.
There will be varying differences between converter output and pan temps depending on how much time the converter is in unlock while running and tend to get closer togather in prolonged unlocked running.
I think you can see from my report that there is more to this subject than most believe.
I have done exstensive research on this and really find little concrete information. This has lead me to do my research in trying to extend the life of the transmission but still understand it will fail at some point in the future.
Another point I will bring you is the fluid used.
The standard fluid has a certain temp breakdown point. Replaceing with a blend or full syn will raise the breakdown temp and should be considered for heavey duty towing. Doing so will not prevent band and clutch wear but delay the effects of breakdown acumulation on overall trans health and life.
What does this mean?
It means that at the point in time the friction materials engage and disengage there is very high friction slippage that causes heat temps beyond the breakdown point of even full syn fluids thus causeing wear that cannot be prevented. If this is difficult to accept just think of what happens each time the brakes are applied and the friction slipping heat that occurrs causing the brake pads to wear. It's the same in a trans but for the cooling help and fluid formulations used and the speed of the shift actions contributing to wear.
A look at fluid condition often while doing heavey towing should be done.
One way is to let a drop on to a paper towel and let it spread out on the paper. If there is not a uniform spread but a darker spot in the center, the fluid is in breakdown and needs to be changed. The dark center area you are seeing is friction material and carbonized fluid.
The deep alum pan has made a significant difference already on the first long tow.
I have given you most all I have learned in general so far and there will be more modifications to cooling in the near future that seems to have never been done before so it will be interesting to see how much lower I can get the towing temps.
One thing I can ensure all is that this amount of cooling cannot be allowed in low cold temps and needs to be backed off for winter driving by reconnecting the radiator into the loop and reducing the total amount of cooling..

[NCCamper2003]

Wow. 125* non-loaded temp in the pan is extraordinary, based on what I am seeing. Matter of fact my "Faris" brand gauge doesn't even mark performance below 140*.

Interesting discussion regarding syn fluids. I would like to change my ATF, but my tranny is at 226,000 miles and climbing, and it seems to be "happy" with what's in there. I am hestitant to do a complete change out. Others here have warned against it. I am sure that the fluid hasn't been changed annually, so I think it's risky.

My loop runs like this: tranny outlet to radiator cooler, to bypass filter (where the temp sensor is), to the external cooler, then return to tranny. I am suspicious of my radiator right now, given the fact that the truck runs at high-normal temps @ highway speeds. When I drop to 45 MPH, then it tends to drop to mid-normal range. I think the trans fluid is picking up heat in the radiator rather than releasing it at this point. And then from there, it passes the temp sensor. I think it's highly likely that the radiator is clogged.

You say you have a dual cooler setup? I just put in a 21,900 GVW filter. If I plan on towing no more than 5500# trailer (and keep within the 60 s.f. wind resistance area noted in the owner's manual), isn't this sufficient?

Thanks for the info!
John

[Bluegrass]

If I understand you correct your temp sensor is after the radiator cooler.
If so all you are reading in essence is the engine coolant temp that the trans fluid is pegged to.
I would move the sensor to the trans outlet where you will see true converter temps that will swing over a wide range and scare you even more but is normal.
All the efforts is the attempt to get those output temps lower on the average.
Two things happen to the fluid.
One is the friction breakdown that collects the resultant contamination in the fluid and the second is the fluid shear that goes on in the converter that deastically raises the fluid temps under high engine loading.
I will have to leave for now but be back later this afternoon.

[NCCamper2003]

Thanks.

Goodness, I hope it's reading more than the coolant temp (in essence) as you suggest. I already have one of those gauges! Though, I suppose that makes sense. But if I read the gauges correctly, the coolant temp (measured at the thermostat I think) is always leading the trans temp, at least until the coolant temp reaches the highest end of normal, when it starts to fall. At this point, the trans temp keeps slowly increasing.

Like others, my sole interest in this is getting the longest life out of the tranny, and of course avoiding breakdowns away from home. That's why I had the bypass filter and the beefier cooler and the temp gauge installed. I also installed a tach, to monitor shift points and engine RPM vs MPH. My XLT didnt have a stock tach.

I will test the fluid quality tonight, using your suggestion.

Thanks,
John

[NCCamper2003]

By the way, here's a shot of my new gauge setup...



Thanks,
John

[MitchF150]

Is your aux trans cooler a stacked plate or tube and fin? The stacked plate will look more like a mini radiator and the tube and fin will look like tube and fin...

The stacked plate is a much better design and size for size, much more efficient.

Those temps seem awful high to me.... I will see 180* on the trans side in stop and go traffic on hot days while towing or not. That seems to be my 'break point' temp... By that I mean it seems pretty easy to get the temp to 180*, but it takes a lot to get it above that. Again, towing or not.

I'm setup with the stock setup, so it goes thru the rad to the cooler and back to the trans. My temp sensor is in the line just before the rad.

I did get my trans temp to 210* while climbing a long grade towing my trailer on a 90*+ day.... The water temp was at 210* as well. The TC was unlocked and when it did lock, the trans temp went down to around 195* for the rest of the pull. Once over the top, the temp went back to 180* when back on level ground. The water temp went back to 195*

If you are seeing higher temps on the water temp side when running on the hwy then something is wrong (oh, you gotta love Fords gauges, huh.... "I'm running a temp of 'M'...". At least your gauge moves... Mine never does. That's why I installed an aftermarket water gauge as well... )

Sounds like you might have a blown head gasket. Not bad enough to allow the exchange of fluids, but enough to allow additional pressure into the cooling system and mess things up.... Could be a clogged rad as well, so do check that out first.

To check for a possible blown gasket, when the engine is cold, remove the rad cap and start the engine. Look into the rad and if you see bubbles, that's pressure in the system behind the thermostat and not a good sign.....

If you feel up to it and are really careful, once you start the engine and check for bubbles, keep the engine running with the rad cap off and wait for the T'stat to open. When it first opens, you should be able to see how well the fluid is flowing. You will probably need to rev the engine to around 1500 rpms to really see what's going on with the flow however... Just be really careful, as the fluid WILL want to overflow out of the open end because of expansion of the fluid, so have the cap ready to place back on or rev the engine to bring it down again... You will want to put the rad cap back on before you shut down the engine too! Or, fluid will overflow out at that time as well...

Good luck!

Mitch

[NCCamper2003]

UPDATE...

I replaced the thermostat this weekend with a 180* Failsafe from AutoZone. This helped the coolant temp problem - now the gauge holds between the "N-O" in normal. Also this has helped the trans fluid temp marginally. The highest I have seen is 230* which to my thinking is 50* hotter than I want. But I am still sensing the temp after the radiator, before the trans cooler. I am going to relocate the sensor to the output line to get a true picture. I also want to validate the trans temp guage. Any way to do this accurately w/o using boiling water (=212* @ sea level)? I would love to use a infrared thermometer, but I think it will not be 100% accurate due to temp radiation. BTW, it looks like the fluid is giving up about 35* after going through the new cooler, so that's a relief.

Let's say that the temp is 230* coming out of the tranny. How excessive is this? What causes excessive heat in transmission fluid? Did I read somewhere that it could be caused by band slippage? What else?

Bluegrass...I did the paper towel test. I can report that the fluid color is consistent throughout the spread - no dark are in the center. That is not to say the fluid looks to be in pristine condition - it does not. My mechanic is advising against a fluid change with the truck having 226,000 miles on the clock. He think my tranny is "happy" with this fluid, and I may stir up trouble within (or maybe unmask a hidden problem).

Any more suggestions?

Thanks guys!
John

[Bluegrass]

The greatest tmp is right out of the converter.
This is because of the fluid shear taking place when unlocked and is normal.
You can't do to much about this. These temps depend on how much load the truck is pulling and for how long a time.
Temps from this can go above 250.
The fluid breakdown is generally above 270 with syn having a higher breakdown temp.
Monitoring at the point you say is not telling you all you want to know because the engine is influenceing the reading you see.
I would reccomend you monitor at the output of the converter but be warned it will read higher than you already like, at times.
Reading the pan only doesnot by it'self tell you what is happening.
And I also question the total value of monitioing in the cae only.
I do both the converter and the pan for data collection then make changes if it looks like it would be helpfull.
I did still have a problem but it was not due to overheating.
On changing the fluid in a hi milage trans, There are two schools of thought.
One is new fluid is slippery and may cause the clutched to slip. Who knows.
I prefer to change it often.
You seem to have gotten almost two lifetimes from your's in terms of trans life..

[stopper]

wow! That is hard to believe that a 4r70w transmission of that year has that many miles on it, with a 3:08 rear end. Something that would help a lot more than a good cooler would be to install 3:55 or 3:73 gears. It would help a lot in towing and not possibly harm your transmission in any way. IF you ever do change your fluid, use MERCON V. It will stand up to heat better, and I believe that if you do flush your fluid now with it, you won't harm your trans or make your clutches slip. If you fluid looks normal, and you replace it with normal fluid, you won't see a problem.

[NCCamper2003]

I bought this truck 1 1/2 years ago and it had 221,000 on it. I am not sure if the fluid was ever changed. I am pretty certain that the trans has never been rebuilt or replaced. But I have heard of these going well over 200,000. Or at least I though I read that here.

Is Mercon V recommended for this trans? I though that was just for newer vehicles but I could be wrong.

Thanks,
John

[98Navi]

Me and Mike determined that my tranny temps had achieved well over 300* during my last fluid expulsion. All thats left for me is to relocate the cooler, since its acting as a heater soaking up the air from the heat exchanger.