Dana 80 Temperatures while towing

[Kirwin]

I recently installed a Cyberdyne digital temperature gauge in my Mag-Hytec rear differential cover and was suprised to find temperatures while towing in the 190-200 F range. Even empty they run over 160 F at 70 MPH. My towing temperatures were recorded on basically level (I-95 between the VA line and exit 181 in SC) with an ambient temperature of 75 F at 72 MPH. My truck is not overloaded (GCW of 14,500 lbs). My gauge monitors the transfer case and transmission also, these are more in order with what I was expecting. Tansmission runs around 180 F and the transfer case is about 10 F cooler. I tried swaping the temperature sender from one to another in case it was a calibration thing but temperatures were the same. I also ran a special ground wire to the differential to eliminate any extra resistance from the sending unit circuit. For the record I use the 75W-140 synthetic oil that it is recommended in the Owners Manual Dodge PN 04874469 and my truck has about 50K miles. Does anyone elce have any history on differential temperatures? What load were you towing? What was ambient temp? Too much information is a good thing!

 

[Boldt's Wagon]

The temperatures are about what I have seen with a 2500 and 70 differential with Redline 80W-140. About 160 solo, up to 210 in the summer with 18,500 GCW. Measured at the top.

 

[Texas Diesel]

Your numbers sound right on to me. I have Mobil 1 75W-90 in my Dana 80 hyrid, and see 150F empty and 180-200F towing @ 70 MPH.



The Maghytec cover puts the sender at the top right where the oil is slung out of the hypoid gears, I suspect that is why we see such high temps. The sump would read lower I think. The temp indicated is not the temp of the assembly just the temp of the oil exiting the ring gear.



BTW, the temp was 20-30F higher with dino 90W before the Mobil 1.

 

[C Schomer]

I tow about 7400 lb 5th wh. . 80 mph, 90 degree day, headwind = 275+ degrees. . 70mph 80 degree day = 250 degrees. It's ALWAYS run hot - before and after all new bearing and setting it up. I also have a Mag cover and 75w140 syn. . Earlier this summer there was a thread and several members reported similar temps so I don't worry about it anymore. My wear pattern shows signs of high torque but there's nothing I can (or will ) do about that. Craig

 

[Dkevdog]

Like others have said, I wouldn't be too worried. I saw temps of 260+ towing 8000#+ with a Dana 70 4:10 setup this summer in 105* heat. I was REAL worried about it at the time, even pulled off a few times, but now I see high temps pretty regularly. I am running Royal Purple 75-140.





Kev

 

[Texas Diesel]

That's amazing, I always thought oil would die if 250F was exceeded for sustained periods.



I pulled a 39', 12,000# 5th wheel to Florida and back in 100F+ @ 70 MPH and never saw over 230F.



Any oil or bearing specialists want to jump in here?



I found this on the Cummins site in reference to an engine oil temp question:



Oil Temp: should not exceed 250-260 deg. F at any time (oil tends to break down, drastically reducing its life, if it runs at temperatures higher than 250-260 deg. F)

--

Joshua Berman MidRange Service Cummins Engine Company

-- email address removed -- Cummins Homepage: www.cummins.com



Has anyone ever asked Dana this question?



Every oil temp gauge I have ever seen has the redline at 250F

 

[John Berger]

I concur

What Texas Diesel said!! Only once have I seen differential temps over 230 degrees and that didn't last long. It was a hot day and I had just pulled some steep grades. I was under 230 the rest of the time.



No flame or criticism intended, but why would anybody want to tow a 5'ver at 80 mph? I'm getting chillbumps just thinking about it. Stuff happens fast enough at 65 mph, which was how fast I was going when my trailer jackknifed and overturned. I occasionally run 70 mph, but usually only on I-95 between Savannah and Kingsland. That section of I-95 is nice and wide and flat with long entrance and exit ramps. Lots of room for correction. But nothing would help in a blowout even at slower speeds, I'm thinking. My truck survived the TT going over, but if the 5'ver goes out of bounds, I'm thinking the odds are nothing is coming back.

 

[pkennedy]

Diff Temps

The D/C Boys again fall short in the information dept. , the synthetic oil used in Dana 80 has higher break down temperature than petroleum oil. If you are overly concerned that the oil is cooking then take a 2-4 oz sample to a analytical lab (bottle and instructions in kit) and they will be happy to tell you the truth about condition of your oil- $20 kit vs $2500 rearend. Once again D/C is a profit driven corporation guess which one they supply? P. S. despite rumors not all synthetics are created equal- lab will verify.

 

[Kirwin]

Dana 80 temps

This is great info. I did a search and found several others that have exceeded 225 F numerous times. I haven't seen above 200 F yet but suspect I would if I were pulling up a good grade in fifth at 70 MPH. It seems to me that speed has as much to do with it as load. I don't know what temperatures the MOPAR brand synthetic lube will stand but lower is better in my book as long as it gets above 120 F. Anyone know who makes this lube that ma MOPAR is selling us for $20/quart? Has anyone done any before and after comparisons with and without the Mag-Hytec cover? Thanks Ken Irwin

 

[pkennedy]

Dana 80 temps

I have not had very good luck finding the identity of Mopar oil origins the dealer only wants to supply a part # and a price. My 2001 is switched over to Amsoil 85-140 for the diffs and I run 10-40 synthetic in engine (no reason to change trans-transfer case) had great success with both in my 91. The truck manufacturers will try to scare you into believing that there product is all that you can use for warranty, in your book that came in the truck is the oil specs as long as you meet these specs they will warrant the truck. Talk to many but get proof in writing eg; oil analysis or maintenance records there are lots of bad luck stories but like any investigation look at the truth. My 91 went 412k 90 Pete 986k on Amsoil P. S. 90% of rearend failures documented as shock loaded (driver abuse) PK

 

[Roger rodbolt]

Kirwin,

Is your sending unit mounted in the top of your MagHytec or in the middle of the cover, below the oil fill level? My experience is that if the sender is in the top it will read higher temperatures. I have mounted sensors both ways and prefer to measure the oil temps near the fill level, but some prefer to measure the oil the is "flung" off the ring gear. Larry

 

[Texas Diesel]

Re: Dana 80 temps

Originally posted by pkennedy

P. S. 90% of rearend failures documented as shock loaded (driver abuse) PK

What is the actual defination of "shock load". TIA.











Roger,



What was the difference in degrees F between the top port and the middle one? TIA

 

[pkennedy]

Shock loading is when torque is not applied to the driveline gradually ie; dropping clutch at more than idle, speed shifting under load racing or pulling a hill and doing burnouts with wheel hop. The gear is made of tempered metal which resists wear it also makes it brittle when shock loaded it will either chip the gear or break it off and there will be a crystalizing pattern where the piece broke off. Sometimes the splines on the drive axles will strip also a hardened surface and in extreme cases the cage will break or the pinion will shear. If you get lucky a U joint will break instead or a driveshaft soaking up the torque load= driver abuse. The price of having fun or not knowing how to use power is repairs at our cost, I will not buy used CTD's with less than 150k that have had new driveline parts put in unless there is a accurate maintenance and proof of part defects. My clutch in my 91 went 412k with 25% clutch wear and 3 sets of brakes. PK

 

[Kirwin]

Sender Location

My sender is in the 1/8" pipe tap at the center of the Mag-Hytec cover. But I believe that, while you are traveling down the road, the inside of the pumpkin is a continuous spray of oil. I think any differences in temperature are do to the specific location of heat sinks such as the cast iron case (in the top mounted location for instance) vice actual differences in temperature. I base this on my experience with reduction gears on nuclear submarines and the oil patterns that are exhibited inside the gear case. I am sure that the oil that just came out of the contact patch between the two gears is slightly hotter but I don't think by much.

 

[Prairie Dog]

Iv'e found that electrical gauges are some what inaccurate and read significantly higher than mechanical gauges when measuring engine oil temps. I know you cant hook up a mech gauge to your diff. because of the distance but I wouldn't be surprised if your elect unit is exaggerating by 20 to 30 degrees or more. Just my . 02$

 

[Roger rodbolt]

Re: Re: Dana 80 temps

Originally posted by Texas Diesel [/

Roger,



What was the difference in degrees F between the top port and the middle one? TIA [/B]

Texas Diesel,

Kirwin pretty much answered your question. A sending unit at the top of the rearend housing gets the "spray" or stream of lube from the ring gear. With heavy loading that stream of lube can be considerably hotter then the bulk of the lube. Similar to checking an automatic trans in the pan or inline before the cooler.

Larry

 

[John Berger]

Nice thing about the sensor being mounted at the top is you should be seeing the hottest relative temperature in the differential.

 

[Kirwin]

Electric gauge accuracy

I can only speak from my experience but I believe that the Cyberdyne temperature gauges are pretty close to dead nuts on. I have a total of 6 senders installed in my two trucks and they all read within 2 F prior to startup after they have sit for >24 hrs. I have also swapped sending units around and run a dedicated ground to each sending unit location that terminates at the body ground wire just below the drivers side hinge. My engine temperature comes up just like the factory gauge and reads 180-185 F when pulling and 175-180 F when cruising empty at 70 mph. I think the trick is to ensure the sending unit and the gauge ground are actually at ground potential. Pressure gages are another story. They are OK for things that are relatively steady but do not react as fast as mechanical gages and the time constants built into the gauge itself to keep the digital reading steady result in sometimes significant delays that make them appear not to be as accurate. IE the sender may be reacting to changes in engine oil pressure when you shift, but the time constant of the gauge itself prevents this reading from ever being displayed. The mechanical gauge does not have this built in delay unless you install a gauge snubber such as is done on the fuel pressure gages to dampen out the pressure fluctuations associated with the cam operated lift pumps.