Truck rear differential is too hot to touch.

[Mikestruck]

I have a 2012 Dodge Ram 3500 Crew Cab 4x4 with a flatbed. I can drive to town and back home and the rear diff is too hot to touch. Is this normal? My truck only has a little over 10,000 miles on it. I am going to be using this truck heavily to pull fifth wheel and bumper pull travel trailers as soon as I retire from the Army. Does anyone have any advice on what oil to put in my diff'sto do this type of work?
I appreciate any help.
Michael Avant

 

[DonFitzwater]

I don't think your situation is normal. I can pull an 8k pound boat 25 miles and the rear diff is about 125 degrees. You should probably get it checked out.

 

[cmills]

I haven't ever checked on my 14, but I have a 99 with the Dana 80 and 4.10's and it gets pretty darn hot, to where you aren't going to hold your hand on it, and it has 344,000 miles on it with never any problems with the rear end. So I guess I would say it is normal, but I don't know for sure. I would check the fluid level and make sure it is full though just in case.

 

[cmills]

now you have me curious, If i remember, I'll check my 14 tomorrow and see how it is.

 

[zmos]

Get an infrared thermometer from Amazon, harbor freight, northern tools, or sears..Should be able to pick one up for around $30 bucks. Then come back to the forum with the measured temp.

 

[Mikestruck]

Thank You for the quick reply. I will take it to the dealership. It is still under the factory warranty. Once I get this problem fixed what oil would you recommend in the diff's If I am going to be towing fifth wheel travel trailers on a daily basis?

 

[DonFitzwater]

https://www.turbodieselregister.com/threads/248764-Rear-Differential-Oil

 

[DonFitzwater]

What part of the world are you in? It will make a huge difference on your diff temps!

 

[Mikestruck]

What will make a huge difference on the diff temps?

 

[DonFitzwater]

Uh, the part of the world in which you live! My ambient temps are in the 20's right now. What's the temp where you live?

 

[Too Tall]

I have a 2500 with 3.42. I checked it in Dallas when the ambient was 102 F pulling 5K at about 63 MPH and the Axle housing was 167 F according to my Fluke Laser Temp gun. This is why they put synthetic oil in them. They will get very hot.

 

[Mikestruck]

Thank You for the reply. I am taking the truck to the dealership where I bought it. It is about 45 miles. I will let them deal with it. This truck is still under factory warranty. I would rather find out about this now instead of in the middle of no where pulling a 15-16 lb fifth wheel travel trailer. I am going to check to see if there is any recalls on my truck too. I want to find out which gear ratio I have too while I'm there.
Michael Avant

 

[Too Tall]

Thank You for the reply. I am taking the truck to the dealership where I bought it. It is about 45 miles. I will let them deal with it. This truck is still under factory warranty. I would rather find out about this now instead of in the middle of no where pulling a 15-16 lb fifth wheel travel trailer. I am going to check to see if there is any recalls on my truck too. I want to find out which gear ratio I have too while I'm there.
Michael Avant

I don't think you got a problem. As I said, I had 167 while towing. That's measured with a laser temp. Unless it's making noise, it's fine. This is why synthetic is used, they run hot. If you want to find out what rear axle you have just go to this web sit and choose equipment listing and put your vin number in. It will list every item on your truck.

http://www.ramtrucks.com/webselfservice/ram/index.html

 

[Kirwin]

I had a digital gauge with the sender in the MH pan on my 03 DRW truck and I rountinely saw >150 F towing. Pullling hard up hill, it could get to 175 F. 120 F is too hot to put you hand on very long. Ambient temperature does have alot to do with it. It takes about an hour of constant high speed to reach equilbrium. Non towing it still ran about 130-140 F at 65-70 MPH after about an hour. I doon't think you have an issue. I'd check the fluid level just to be on the safe side. if fluid level is OK then I'd leave it alone. If its low then I'd open her up, change the fluid, and inspect the gear contact pattern when it's convienent just to see whats going on in there. But the temperatures you are seeing are normal in my experience. Ken Irwin

 

[Mikestruck]

Thank You for the information.

 

[Too Tall]

I had a digital gauge with the sender in the MH pan on my 03 DRW truck and I rountinely saw >150 F towing. Pullling hard up hill, it could get to 175 F. 120 F is too hot to put you hand on very long. Ambient temperature does have alot to do with it. It takes about an hour of constant high speed to reach equilbrium. Non towing it still ran about 130-140 F at 65-70 MPH after about an hour. I doon't think you have an issue. I'd check the fluid level just to be on the safe side. if fluid level is OK then I'd leave it alone. If its low then I'd open her up, change the fluid, and inspect the gear contact pattern when it's convienent just to see whats going on in there. But the temperatures you are seeing are normal in my experience. Ken Irwin

Agree, same your experience also. And if it's not growling or noisy, it's fine. If there was a problem causing overheating, it wouldn't take long for the thing to start talking to you. You've got such a small amount of fluid relative to the huge gears and load they are carrying. Also agree higher the ambient temp, the higher the oil temp. Heat dissipation is better in colder weather. I suspect the taller the gear ratio, the hotter they run, but I don't know that for a fact.

 

[Mikestruck]

Agree, same your experience also. And if it's not growling or noisy, it's fine. If there was a problem causing overheating, it wouldn't take long for the thing to start talking to you. You've got such a small amount of fluid relative to the huge gears and load they are carrying. Also agree higher the ambient temp, the higher the oil temp. Heat dissipation is better in colder weather. I suspect the taller the gear ratio, the hotter they run, but I don't know that for a fact.

Thank You for the information. These trucks are expensive. I just didn't want to burn anything up. I took my truck to the dealer. It is still under the 5 year 100,000 mile warranty. They checked it out. They said that it is fine. They also told me not to ever use any other type of oil in the diffs no matter what I pull. There is a certain additive in the Mopar oil that must be in the diff in order for it to pull. That is what they told me.
I did find out that I have 4:10 gears.
Thanks again for answering my post.
Michael Avant

 

[Ram4Sam]

Thank You for the information. These trucks are expensive. I just didn't want to burn anything up. I took my truck to the dealer. It is still under the 5 year 100,000 mile warranty. They checked it out. They said that it is fine. They also told me not to ever use any other type of oil in the diffs no matter what I pull. There is a certain additive in the Mopar oil that must be in the diff in order for it to pull. That is what they told me.
I did find out that I have 4:10 gears.
Thanks again for answering my post.
Michael Avant

"They also told me not to ever use any other type of oil in the diffs no matter what I pull. There is a certain additive in the Mopar oil that must be in the diff in order for it to pull."......:-laf:-laf:-laf:-laf

Sam

 

[Too Tall]

"They also told me not to ever use any other type of oil in the diffs no matter what I pull. There is a certain additive in the Mopar oil that must be in the diff in order for it to pull."......:-laf:-laf:-laf:-laf

Sam

Agree, Yes, I called today, $19 per quart for the Mopar synthetic. The front (4 x 4) uses the same. They look up your vin number because they have had changes. I wouldn't just get some GL 5 from autozone. Could be using the wrong stuff.

 

[Camperman]

When I changed my rear diff fluid, I used Amsoil Severe Gear 75W/90. Took a bit over 4 quarts on my 2012