Engine/Transmission (1994 - 1998) Rear End Temp ranges

[Dkevdog]

Just got back from a 2600 mile trip with the new fiver and had the rear end temp guage hooked up this time. I've got a Dana 70 with the Hytek cover and running through the 110* desert I saw temps reach at least 250* - couldn't tell how much higher, I only got a guage that reads to 250. transmission guage never went above 170*. I got pretty scared when I saw the high rear end temps. Is this normal or am I cooking breakfast back there!?!



Kev

 

[Steve Campbell]

I do not have a guage...

Kev, but when I first bought my 99, I was wondering how well the drivetrain would stand up to all the torque and horsepower. One of the trucks I had was an 82 Freightliner that put the same HP to the ground as my slightly modified pickup now does. I had guages on those rear ends. I was running dino oil in them and if the temp guages showed above 250, I was getting nervous and usually changed the oil right away to see if pieces of parts that weren't suppose to be in the oil, were in the oil. Usually things were OK. Other than power divider problems, the rear ends went 350,000 miles and a lot of them the guage read betrween 225 and 250deg.



Long story short, 250 is probably not catastrophic by itself, but you may want to consider a better oil or the aluminum rear cover to keep the temps down.

 

[Boldt's Wagon]

I have seen 210 since installing the temp sensor this spring. Maximum outside temp of about 80 while towing 11,000 lb fifth. I have a Mag-Hytec cover and am using RedLine 85W-140 synthetic gear lube.



I think your temp looks normal for 110 outside temps. I think that synthetic gear lube might be a good idea for towing heavy.

 

[Dkevdog]

I'm going to get a guage that reads to 300, but the temp seems to be more dependent on speed than anything else. Climbing 7-12% grades in the mountains (25-35 MPH) the temp usually stayed below 200. Running 65-70 MPH for long periods is when I saw the 250+.



I am using Royal Purple Synthetic 85-140w and have the Hytek cover already. So if temps are high, I don't know what to do.



Kev

 

[amsoilman]

Kev,

I have the Mag-Hytec cover on my Dana 70, and use the Series 2000 Amsoil 75W-90 gear lube. My gauge has never been above 200 F. no matter what temps I have run in. DiPricol gauge mounted in top of diff. cover.



Wayne

 

[Robin]

The ring gear merely thrashing the axle lube can heat it without any significant pulling load. A good example of this is overlubing ball bearings in motors which will cause high temp. So your observation of temp rise during high speed running may have hit the nail on the head. What temp do you see when running empty at 70 MPH? Bob

 

[Extreme1]

230 is a pretty average differential oil temp. Lots of oil shearing going on and that produces heat. Towing makes it worse. The number to get alarmed about (as I recall) is 320.



I would get a higher guage though.

 

[amsoilman]

Extreme1,

Are you sure you have your numbers right? I certainly don't think temperatures approaching 320 F. is good for any lube! As I recall, when you reach 300 F. on oil, the components begin to distort. Once you reach 300 F. the oxidation rate will triple!



Wayne

amsoilman

 

[FL70CAT]

Remove conventional oil-------install in its place Amsoil series 2000 85-140 and don't worry about it. I'm pretty sure the series 2000 has a good bit of headroom in it even at 300 degrees farenheit.

 

[Dkevdog]

I don't want to start an Oil war here, Amsoil, Royal Purple, Whatever you want each to his own . With that being said, I highly doubt changing to Amsoil is gonna make a difference in temp. Towing a 30' fifth wheel through a 110* desert with a 4:10 rear end is gonna make heat no matter what. At 70, I'm turning 2250 RPM. Running empty around town (today was a good test) I saw temps only reach a max of about 150* or so. That was freeway driving at about 70.





Guess I'll get a higher guage and call it a day.





Kev

 

[SlyBones]

Originally posted by amsoilman

DiPricol gauge mounted in top of diff. cover.

Wayne

Well just to show how stupid I am, I gotta ask? Are we measuring case temps or oil temp? If were checking gear oil temp, how does that work with the sender in the top of the diff cover? I thought thats why there was one on the side, so it stick into the middle of the oil?

 

[amsoilman]

SlyBones,

Perhaps I didn't explain correctly. The gear lube sensor is mounted near the top of the diff cover . The sensor does protrude into the gearbox where the lube is thrown onto the probe to sense the temperatures. It was found during the early developement of the "Mag-Hytec" differential covers, this location of the sensor was the prefferd location as opposed to the bottom where the gear lube collects. During the testing phase of the "Mag-Hytec" covers, the gear lube comeing off the Ring and Pinion gears was hotter than the bottom location by some 15 F.





Wayne

amsoilman

 

[SlyBones]

Wayne, thanks. If I ever install a sender in my magHytec diff cover, I will know the correct way to do it. Nothing wrong with the info provided above. I just didnt know and saw something that confused me. So I asked. Thanks again.

 

[QRTRHRS]

On a related matter....

Originally posted by amsoilman

SlyBones,

Perhaps I didn't explain correctly. The gear lube sensor is mounted near the top of the diff cover . The sensor does protrude into the gearbox where the lube is thrown onto the probe to sense the temperatures. It was found during the early developement of the "Mag-Hytec" differential covers, this location of the sensor was the prefferd location as opposed to the bottom where the gear lube collects. During the testing phase of the "Mag-Hytec" covers, the gear lube comeing off the Ring and Pinion gears was hotter than the bottom location by some 15 F.





Wayne

amsoilman

Wayne, that said, what are your thoughts on the merits of probing a five speed via the fill hole plug? I bushed down to make an easy connection. Reading about 170-175 at 70-75 mph, 80 degree day, empty, relatively flat road and 4:10's by the way.

 

[Turbo Thom]

I was towing my fiver in the Va mountians with the outside temps at 93-95, runnin 65 and the rear end reached 190 one time. That is with the Mag-Hytec and series 2000 75W-90. The transmission, a five speed, reached 230, once. Now I have the fast coolers and series 2000 in the transmission. We'll see now.



. . Preston. .

 

[Steve Campbell]

Mag hy-tec...

just how much on the average does it lower the rear end temp---all else being equal?

 

[Joseph Donnelly]

Use premium lube. If the diff still gets hot, backlash may be set too tight and/or no preload on the carrier side bearings.