05 3500 Auto Trans overheating

[dodgeliner]

I frequently pull a 14k gooseneck and trans temp gets up to 240 after a long slow pull up a mountain with lots of switchbacks keeping me in the 25-35 mph range. I know the reason is the torque convertor can't lock up going that slow. I have searched and it appears I can get the super cooler and it may cool the trans temp enought, but if I changed to a better torque converter, would that be the better fix?



Any help would be appreciated... Thanks

 

[jelag]

We have 2 trucks with auto's that pull... ... thier not dodges that I have listed below...



To keep the transmission from overheating on both trucks... . we installed an extra transmission cooler thats rated at 14, or 15K lbs as I remember... . this was the only way we could drop the transmission temp to below 200 on hard pulls... . We've never changed the torque converter... . as we have no mods to the engines or transmissions... Frankly..... I'd never own another automatic the way we use them... . unless I felt it was up to it like the allison is... ...



Hope this helps. .

 

[CPittman]

Couldn't hurt... but I think a lockup controller should be at the top of your list along with the new torque converter. That way you can force lockup while climbing to keep things cooler AND force lockup once you're on the downhill to take advantage of the retarding power of a jake brake.



I really think a new TC from one of the top 5 suppliers with the lockup controller AND a double-deep Mag Hytec pan would be a better investment than the supercooler, IMHO.



All these guys make great aftermarket torque converters and most make some kind of lockup controller too:



DTT Diesel Transmissions

ATS Diesel Performance

Dave Goerend Transmissions

SunCoast Diesel Transmissions

Dunrite Converters



My Mag Hytec double-deep pan

 

[Bertram65]

I frequently pull a 14k gooseneck and trans temp gets up to 240 after a long slow pull up a mountain with lots of switchbacks keeping me in the 25-35 mph range. I know the reason is the torque convertor can't lock up going that slow. I have searched and it appears I can get the super cooler and it may cool the trans temp enought, but if I changed to a better torque converter, would that be the better fix?



Any help would be appreciated... Thanks

If you put the shifter in 2 it should lock in 2nd, I have done it many times when I was on windy roads at slow speed going up and down alot. What gears do you have? if you have 3. 73s it may be a little faster than what I have seen with 4. 10s. Where are you measuring the temp?

 

[BHolm]

unless I felt it was up to it like the allison is... ...

:-laf :-laf :-laf Now THATS Funny... . You mean like a real Allison in a bus right? Not like the one that burnt up in my Chevy pulling a 4000 lb boat

 

[dodgeliner]

I am using the Banks PDA, so I assume it gets its trans temp to the factory sensor.

 

[Bertram65]

I am using the Banks PDA, so I assume it gets its trans temp to the factory sensor.

What does it read in normal around town driving?

 

[Prairie Dog]

:-laf :-laf :-laf Now THATS Funny... . You mean like a real Allison in a bus right? Not like the one that burnt up in my Chevy pulling a 4000 lb boat

No kidding, I cant tell you how many forumns I've read about Allisons boiling over.

Now, Allison does have a motor home rated trans for use behind our little Cummins. I'd sure like to see that offered on our trucks!



Scotty

 

[BHolm]

No kidding, I cant tell you how many forumns I've read about Allisons boiling over.

Now, Allison does have a motor home rated trans for use behind our little Cummins. I'd sure like to see that offered on our trucks!



Scotty

I owned two of those trucks, both had trans problems. I have a LOT more gas for that fire but it is a little pointless :-{}



I have a trans temp sensor in the transmission line (Mass Diesel). If the situation allows the convertor to lock I never go above 160, no matter how big the load. I will also have some tight winding mtn road driving coming up this winter but nothing like the load you pull, I'm just pullin sleds for fun I will be curious though how high mine gets. I know its not enough to run empty, that doesn't bring the temp up at all.



My only concern would be if the trans could handle extended hard pulls with the convertor locked in first. The convertor, while it build heat, it also takes some of the shock loads. I suppose though, you would be in second most of time. The '06 will lock in second so the trans should be able to handle it. I think one of the aftermarket lower stall convertors, valve body and lock up controller would be the ticket. A bigger cooler will definately help though, and that is by far the least expensive fix, if it works.

 

[TCDiesel]

The more efficiency the TC at Low RPMs the more heat it will create,If you lockup to early and drop engine rpms than you will create engine heat and the primary cooler (heat exchange) will transfer the heat to the transmission fluid and compound your problem. The fluid cooling is very complex on 3gen. we have installed coolers that are design to cool 100 gallons Plus all this does is add time to reach Max Temp,and in most cases lengthen the spread 5 to 7 minutes when pulling heavy and hard. the solution is simple FAN override switch.

 

[BHolm]

The more efficiency the TC at Low RPMs the more heat it will create,If you lockup to early and drop engine rpms than you will create engine heat and the primary cooler (heat exchange) will transfer the heat to the transmission fluid and compound your problem. The fluid cooling is very complex on 3gen. we have installed coolers that are design to cool 100 gallons Plus all this does is add time to reach Max Temp,and in most cases lengthen the spread 5 to 7 minutes when pulling heavy and hard. the solution is simple FAN override switch.

Huh Lower stall convertors generate less heat because there is less fluid shear in the convertor. It is well known that a higher stall convertor generates more heat. I'm really not sure what you mean by a more efficient convertor making more heat, isn't that completely contridictory?



The next part where if you lock up too early you will cause the engine to make more heat and that will transfer to the trans. So define for me too early. I would bet that he could run 2000+ rpm real easy, locked up. If you lock it up the trans is now generating minimal heat because there is no fluid shear in the convertor anymore. It is now very similar to having a manual trans and as long as you don't lug it down below 1800 rpm or so, there isn't going to be the extra heat you speak of generated. Do the manual trans guys know about this :-laf Just imagine the heat they are generating with their solidly coupled engine and trans.



It is also pretty far fetched to claim that a heavy load on the engine is contributing to the trans heat. Funny how the engines run about 200* normally and the trans only runs 160* If your assertion was accurate wouldn't the engine temp pull the trans temp up? The trans itself has to contribute to the heat. The convertor is the biggest heat producer. It you lock it up and stop that source of heat the burden on the cooling system will drop, not the other way around.

 

[DieselFiend]

I'd do one thing at a time to help your budget. First thing I'd do is get a lock-up controller. If you're still having heat problems after that, I'd move to a new TC. Then after that, I'd go for the supercooler. Thats just me.

 

[TCDiesel]

Huh Lower stall convertors generate less heat because there is less fluid shear in the convertor. It is well known that a higher stall convertor generates more heat. I'm really not sure what you mean by a more efficient convertor making more heat, isn't that completely contridictory?



The next part where if you lock up too early you will cause the engine to make more heat and that will transfer to the trans. So define for me too early. I would bet that he could run 2000+ rpm real easy, locked up. If you lock it up the trans is now generating minimal heat because there is no fluid shear in the convertor anymore. It is now very similar to having a manual trans and as long as you don't lug it down below 1800 rpm or so, there isn't going to be the extra heat you speak of generated. Do the manual trans guys know about this :-laf Just imagine the heat they are generating with their solidly coupled engine and trans.



It is also pretty far fetched to claim that a heavy load on the engine is contributing to the trans heat. Funny how the engines run about 200* normally and the trans only runs 160* If your assertion was accurate wouldn't the engine temp pull the trans temp up? The trans itself has to contribute to the heat. The convertor is the biggest heat producer. It you lock it up and stop that source of heat the burden on the cooling system will drop, not the other way around.

BHolm, The Info Is correct,My suggestion to you is to Install a 89/91 Tc and Use a 20,000 GVW test trailer . Now do some off road Driving and see How fast you Trans Temp will raise,within 10 minutes or less you will see 220 plus trans 210 plus engine.

I understand your point on lockup, But when you are in fluid coupling and Pulling heavy up steep grades a new rule Book must be used. I also I have Equipment that I use Daily for My construction Business,On any given Day I am Pulling 20,000 to 30,000 GVW on and off road... Their are so many contributing factors to the heat ,Speed, grade, surface,Rpm"s gear Ratio"s,Weight,AC,Pump,System,etc,add to this a thermostatically control system ,you had better know what you are doing if you tamper with it. Even excessive Backing effect trans Temps, That why many Members and Guess here at the TDR have install the fan override switch and Love the results.

 

[COBRAJET]

The cooler system on the gen 3 trucks is very complex. The system uses the primary cooler to maintain temps and will bypass fluid out of it back to the transmission until the desired temp is maintained. Once the primary capacity is exceeded the fluid is diverted to the secondary cooler mounted behind the radiator. Adding coolers or deep pans does nothing. My truck ran 180 degrees according to the edge unit... . 160 with an infrared gun shot at the pan empty at 70mph in 105 degree heat. I added the deep hytec and synthetics and saw the same temps... only 10 minutes later. It took the transmission that much longer to heat up the bypassed fluid. I added a cooler between the factory cooler and trans and saw the same temp only 30 minutes later. I took it off.





While towing a 14K fiver the trans ran at exactly the same temp at the same speed and outside temp... proving the factory setup was working. While towing in town or heavy grades at slow speeds the engine and trans heat builds. At this time the fluid is diverted to the cooler behind the radiator. At slow speeds with little airflow the radiator fluid is hotter than the engine. It could easily be 220. By the time the fan kicks in it is drawing air off a very hot radiator across a very hot transmission cooler. Not much cooling taking place here. The trans not being locked is also producing heat. This scenario is short lived, but the trans fluid does not cool quickly. If it is a long pull at slow speeds in hot temps it is a pain on both cooling systems. 240 degrees is not much of an issue with synthetics.



Having a fan switch bypass as TWest describes brings the fan on sooner keeping up or getting ahead a little bit on the engine and trans heat. Running down the highway at speed has the engine at 200 only because the Tstat has it there. The trans at 160-180 has fluid only running through the primary cooler which does not get any radiator heat. Once it goes to the secondary cooler behind the radiator due to slow speeds not cooling the primary enough or trans heat build up due to non lock up... . which also has the engine heating up due to this speed it has no choice but to be at or near the radiators temp since the air cooling it goes through the trans cooler which already has very hot fluid in it if it is heading to this cooler instead of being bypassed back to the transmission. The only way around this is to build your own setup which would mount coolers with fan/fans under the truck away from the radiator which you could control the temps with by fan cycling. Other trucks including the Hemi have the trans cooler mounted next to or partially under the radiator to help alleviate this problem. The Ram Hemi radiator is mounted to the side with the coolers on the other side. The PSD's I have owned had it partially under the radiator. It did not use a bypass either after leaving the radiator exhanger on its way to the secondary cooler. In cold weather it simply ran cooler... as low as 110-120 in the winter at speed. The 3rd gen is not set up that way... it will bypass fluid to maintain temp.

 

[BHolm]

BHolm, The Info Is correct,My suggestion to you is to Install a 89/91 Tc and Use a 20,000 GVW test trailer . Now do some off road Driving and see How fast you Trans Temp will raise,within 10 minutes or less you will see 220 plus trans 210 plus engine.

I understand your point on lockup, But when you are in fluid coupling and Pulling heavy up steep grades a new rule Book must be used. I also I have Equipment that I use Daily for My construction Business,On any given Day I am Pulling 20,000 to 30,000 GVW on and off road... Their are so many contributing factors to the heat ,Speed, grade, surface,Rpm"s gear Ratio"s,Weight,AC,Pump,System,etc,add to this a thermostatically control system ,you had better know what you are doing if you tamper with it. Even excessive Backing effect trans Temps, That why many Members and Guess here at the TDR have install the fan override switch and Love the results.

I never said you couldn't overheat a trans if you just changed the convertor. Certainly if you overload the truck by 5000 lbs you stand a good chance of getting it warm.



You you live in MN and are telling ME about off road and grades :-laf I lived there over 30 years, you should get out more dude. There are no grades and off road to me is more than just a jobsite. I know jobsites, I was in construction for 10 years as a supplier and made thousands of jobsite deliveries. Sure backing can raise temps, anytime you are running aginst the convertor you will get heat. However, if you have tighter convertor than stock, you will build less heat, less quickly. A fan override is a good idea, I would agree. I think lock-up control would be even better, though more $$.



As far as knowing what you are doing before "tampering with it" I might try to kindly suggest that you might have some to learn as well sir. Your grasp of the subject matter seems tenuous at best.

 

[TCDiesel]

Please do not refer to me as dude, My Name is Todd ,Twest, or TDR member, Have you ever been to ELK river Landfill ,Or Black Dog, 8% grade or Better in some spots it"s not Long but I have seen trans temps raise 40* in the 90 plus heat from bottom to Top this summer , BHolm just try and keep a open mind on the subject I now consider this Closed, at any-rate take care.

 

[COBRAJET]

TWest has more knowledge about how the Gen 3 transmission cooling system works than most. It would appear that most of the people replying do not. The bypass in the system creates a lot of issues by not letting the fluid flow through both coolers all of the time like most trucks out there... ie PSD's and Dmax's. Full flow through both coolers does not take place all of the time as would be expected. Once the secondary cooler sees fluid the conditions for it to rise quickly have usually been met. Slow forward speeds loaded or unloaded will raise the trans temp. Locking the TC in second can be achieved by placing the trans in second... only in the 06 trucks. This will reduce trans heat, but could increase engine temps due to possible lugging of the engine. If this happens and the bypass has opened to the fin cooler the fluid is going to rise regardless of whether the trans is locked up or not. The intercooler/radiator heat is being transferred to the trans cooler. Monitoring the trans temp guage is the only way to tell if this is happening. Unloaded it is likely not going to happen since the engine is not being worked that hard.



Loaded is a different story... locking the convertor in second towing a heavy load is going to build heat in the engine very quickly if the truck is lugged even the smallest amount which the TC would take care of it was not locked. But that builds heat as well sending the fluid to the fin cooler where it is likely going to stay hot since the truck has very little air going across this cooler in this scenario unless the fan is on... which means the engine is getting hot as well. It is a ugly cycle. Worst case scenario is having a hot fin cooler sandwiched between the engine intercooler and hot radiator. Not very efficient.



Solutions include pulling over with the transmission in neutral at high idle. The engine cools down and so does the trans fluid. Another cooler can be added, but there is no value to it unless the fluid temp is rising while running through both factory coolers with the fan engaged. A scenario not to common, nor one which lasts a long time unless the truck is pretty much being abused since the transmission has to be slipping or the truck engine is being taxed very well for a long period of time with very little forward movement.



The cooler can be installed before the fluid gets back to the transmission but it will do absolutely nothing unless the truck is in the above scenario. The primary cooler keeps the fluid cool unloaded at speed and any combination of the two coolers keeps mine at 180 towing at max combined at freeway speeds. If the added cooler was on the truck the factory bypass would simply start to bypass fluid back to the transmission avoiding the secondary fin cooler and the installed cooler before it had a chance to do anything. As soon as it got warm from bypassing it would go to the fin cooler and get what it needed go back to your added cooler where once again the fluid would get below the factory setting causing bypassed fluid again. You would be doing nothing but giving the bypass valve a very good workout for no reason whatsoever. If I was using my truck in a matter that caused my fluid to be at 240 on a regular basis I would mount the cooler... with a fan that I could cycle under the bed to keep the temps a little lower. The factory TC is a obvious compromise. Trucks which get the "sweet" TC's are generally BOMBED and are not receving them for their "towing" superiority. They are part of the complete transmission rebuild required to keep the trans shifting and the TC from not melting due to all the slippage from the easy to purchase plug in HP/TQ.



I would install the fan switch and see how that works. If that does not cure the problem add the cooler with fan. This is not much money or time. Replace the TC when it gives up the ghost. In this order you will have the switch and cooler already mounted for the the new TC that does the exact same thing... . speaking from experience. I had two Ford autos behind 7. 3 PSD's rebuilt to the hilt by Brian's Truck Shop... a very well respected outfit and they both ran hotter going down the freeway than the factory ones did.

 

[cerberusiam]

Worst case scenario is having a hot engine/radiator being asked to cool a transmission by having air drawn across it

Huh?? Not sure what you are trying to say,but unless the 06's have a major design difference ,the trans cooler is in FRONT of the radiator not behind it. The only impact engine heat has on the trans is the heat exchanger on the side of the block.



The 05 autos will lock in 2nd gear manual also. If you are that heavy and slow that drive won't stay locked in Tow\Haul you might want to try a simple switch to lock the TC and help with the heat. That along with the fan switch should address the problem.



Interesting info on the heat exchanger and bypassing. Guess they had to design something different after down sizing the heat exchanger so much.

 

[Bill Stockard]

Huh??

The 05 autos will lock in 2nd gear manual also.

So does my '03



Bill

 

[ropinfool2]

I need more info on the fan bypass switch. Thanks. JR