How hot should a diff cover get?

[Red Willy]

Just ran on the interstate for a short trip (50 miles each way) at around 75 mph. When I got home I was under the back of the Jeep checking a few things and found the diff cover was rather hot. I checked it with a meat thermometer held against it with a rag and it went up to about 155. I know the oil is full as it was just changed with synthetic and friction modifier. Is that much heat normal?

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[jaymz]

Temps into the mid to high 200°s ballpark are normal. Numerically lower gears will obviously run cooler. Maybe high 100°s to low 200°s.

 

[1996cc]

Hottest I captured during my latest gear break-in. I think I may have seen 180ish. I wouldn’t worry unless you see 250…

 

[dragoneggs]

That’s rather cool. No worries at all.

 

[CarbonSteel]

75MPH @ 95°F ambient temperature:

 

[CarbonSteel]

Hottest I captured during my latest gear break-in. I think I may have seen 180ish. I wouldn’t worry unless you see 250…

Obviously, the oil is much hotter than that and those type guns vary widely in both accuracy and range.

 

[1996cc]

Obviously, the oil is much hotter than that and those type guns vary widely in both accuracy and range.

Agreed. What made you run separate temp gauges for them? I’ve never seen that outside a racing environment.

 

[dragoneggs]

Obviously, the oil is much hotter than that and those type guns vary widely in both accuracy and range.

Yes the oil likely is hotter than the outside surface temp of the cover. And ‘those types of guns’ can be very accurate. Most importantly, one must understand how they measure… specifically the cone (area) they measure vs. the distance between the gun and the surface.

 

[CarbonSteel]

Agreed. What made you run separate temp gauges for them? I’ve never seen that outside a racing environment.

I had them on my Powerstroke and moved them over when I bought the Grinch. Glad I did, I have been very surprised at the heat these axles generate. The probe is directly in the oil stream on both axles.

 

[CarbonSteel]

Yes the oil likely is hotter than the outside surface temp of the cover. And ‘those types of guns’ can be very accurate. Most importantly, one must understand how they measure… specifically the cone (area) they measure vs. the distance between the gun and the surface.

The oil will definitely be hotter as the axle housing works as a heat sink and pulls the heat away and disperses it fairly quickly.

I have that exact model and tried to measure the temperature of a propane torch flame. It wasn't anywhere close to reality no matter what distance was tried. <shrug>

 

[Red Willy]

Thanks for all the replies. I just never noticed, but since I had the gearing changed, I'm kind of paranoid and seem to look for possible problems before they compound.

 

[dragoneggs]

I have that exact model and tried to measure the temperature of a propane torch flame. It wasn't anywhere close to reality no matter what distance was tried. <shrug>

Good luck with that! Most infrared thermometers have a range up to about 1000degF, maybe a little higher in your case. Your propane torch flame is well over 2000degF.

I think this is the one you have…
https://www.amazon.com/Etekcity-Las...76743983&sprefix=Infrared,aps,242&sr=8-3&th=1

Then the other issue is the distance to spot measurement. Typically 10:1 or 12:1 (your case?). The optimum distance is usually around a 12in or so. Meaning you will be measuring a spot about 1in in diameter and getting an average not a peak temp. In my case the beam is a little wider…

Knowing the capability and how to use them is important. I can’t vouch for the accuracy of yours but my Raytek MT6 that I use for work is quite accurate when used within it’s published parameters.

 

[Valpo Jeep]

According to what I can find from Google, 175F to 250F is normal. Above 250 and the fluid breaks down

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