How hot is too hot?? Rear diff temps??

[WIS-key]

Originally Posted by bestatchess

As far as testing with your hand, I think both 150 and 180 will feel pretty hot and my hand is not that precisely calibrated. Isn't 180F about the hot setting on a home water heater that will scald your hand?

I suspected that both 150 and 180 were really hot, but wasn't sure. This is from the Consumer Products Safety Commission:

Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds. Burns will also occur with a six-second exposure to 140 degree water or with a thirty second exposure to 130 degree water. Even if the temperature is 120 degrees, a five minute exposure could result in third-degree burns.

All I can say is wow - it really doesn't take much heat to do damage. This really surprised me.

-Rob

[CaliforniaTitan]

titanbjc "Is there a correlation between diff problems and areas of the country? One exploded diff was in AZ, I think, the other southern CA, where temps have been higher. I live in MA and yesterday was the first day over 90. I would think the diff runs hotter if it's 90+ deg. vs. 40s-60s...
"

I don't see one...our outside temps during our commute are closer to 80 and below....

Chris

[bestatchess]

Originally Posted by titanjbc

Is there a correlation between diff problems and areas of the country? One exploded diff was in AZ, I think, the other southern CA, where temps have been higher. I live in MA and yesterday was the first day over 90. I would think the diff runs hotter if it's 90+ deg. vs. 40s-60s...

There could be a correlation as air flow past the differential is cooling the differential, and colder air would cool better. As I recall from my heat transfer class about 25 years ago, the equation will have a bunch of stuff (I am way too lazy to do any differential equations at this point) multiplied times (Temperature of Diff. - Ambient Temp.) so as Ambient Temp. drops, this term gets bigger and the amount of heat transferred gets bigger. Of course, whether the diff burns up depends on the balance of heat generated in the diff. - the heat being transferred out.

[CaliforniaTitan]

I don't disagree it may runner hotter than in the cold. What I meant by my statement is do you think they would design/build/sell a car that you can't drive in over 80 degree weather? LOL

Chris

[bestatchess]

Originally Posted by CaliforniaTitan

I don't disagree it may runner hotter than in the cold. What I meant by my statement is do you think they would design/build/sell a car that you can't drive in over 80 degree weather? LOL

Chris

I am hoping not, although I am wondering why they would use a quart less fluid in the rear differential than employed in other 1/2 ton trucks with less HP and lower tow ratings.

[SUBTITAN]

Yes a bigger D/T will increase heat transfer. So it should run cooler in colder temps. If I recall all the research I did before buying they tested this truck in the Arizona dessert right? I'm not sure what kind of heat transfer you get off that casing, but I would imagine its not too much. I have a lazer thermometer. I will get it from work on monday and do some testing on ambiant temp verses differential temp. One of the great things about SoCal is you can get a wide range of ambiant temps and only have to drive a few miles.

[stevemis]

Originally Posted by SUBTITAN

Yes a bigger D/T will increase heat transfer. So it should run cooler in colder temps. If I recall all the research I did before buying they tested this truck in the Arizona dessert right? I'm not sure what kind of heat transfer you get off that casing, but I would imagine its not too much. I have a lazer thermometer. I will get it from work on monday and do some testing on ambiant temp verses differential temp. One of the great things about SoCal is you can get a wide range of ambiant temps and only have to drive a few miles.

Awesome, Subtitan! I'm looking very forward to seeing some numbers.

-Steve

[stevemis]

I shot my Beater Truck (1990 Chevy C1500) with the same pyrometer after a similar drive (under similar conditions) and had readings of 110 degrees F at the center of the differential.

-Steve

[Doug]

Isnt this all covered on the warranty???

[TriKKy]

Yes, but the repair on a blown one has already been a month for another member....speaking of which, Nissan give you a loaner for that?

[extunder]

I can't remember a truck that didn't lose the finish on the diff, and everything else underneath, for that matter.

[FLfinfan]

I can't remember any truck or SUV I have ever owned loseing it's diff cover paint.
This includes 1 Titan (so far), 2 Frontiers, 1 Nissan 720, 1 Xterra, 3 Pathfinders, 1 Mazda pick-up.

Parents have owned a few SUVs (Honda Passports aka... Isuzu Rodeos) also with no problems in this category.

[juma]

Originally Posted by bestatchess

I am hoping not, although I am wondering why they would use a quart less fluid in the rear differential than employed in other 1/2 ton trucks with less HP and lower tow ratings.

I don't think that's right. my '97 chevy van had a 2 quart cover and I think this is still the standard chevy half ton 8.5 inch rear end. I think titan may be using this lower capacity too for higher gas mileage. the chevy's half-ton pickups get pretty good gas mileage (low 20's). Now that I think about it, I didn't get quite as good a mileage after changing over to a higher capacity cover...maybe. It never seemed to get much over 17 after. before I think I used to get in the 18's. anyway, I recently wrote concept pattern to see if they have or will make a 3 quart finned aluminum differential cover. If they will, I'm definitly getting one. juma

[bestatchess]

Originally Posted by stevemis

I shot my Beater Truck (1990 Chevy C1500) with the same pyrometer after a similar drive (under similar conditions) and had readings of 110 degrees F at the center of the differential.

-Steve

I shot the center of my rear diff. cover with the same little RayTek this morning after a 20 minute, relatively low speed drive to work, with a short stretch of 65 mph on the highway, and it was 146 F.

I am going for a longer highway drive tomorrow, so I will check it again.

[bestatchess]

After 1/2 hour of 65-75 mph highway driving, the rear diff temp was 160 F today.