I recently had a rear seal and gasket replaced and decided to check my differential temps in case they forgot to refill my rear end. Figuring if no fluid was in there it would get quite warm.
With the outside temp being about 63 degrees my rearend was at about 130 degrees after one hour of 55 MPH.
I know on my pickups pulling trailers in the past that the paint was burned off the rearend housing. The GM dealer said that was normal on those pickup trucks. (1999 GMC 1500 and 2003 2500HD).
Have any of you checked your rearend temp with an infrared temp gun?
What temps are you seeing?
I am also going to change the rear fluid but it looks like a real pain to get the new fluid back in.
Any thoughts?
2004 Monaco
La Palma 36DBD
Two Slides
2 Potties
Workhorse 22 chassis
8.1 gas engine & Allison transmission
6.9 MPG based on a 6,000 mile trip around the U.S.
I had a friend with a hopped up Econoline van with a large straight 6, and he could get the rear axle over 300F, so he had to slow down if it went over that temp. This was with a manual transmission and clutch out of a Mustang.
I would not worry about it being 150F. But remember that when it is 100F outside, it will reach about 175 fairly easy. More than 250F means somthing is not aligned correctly in the rear axle in most cases. He had a dash gauge, and when he was not towing, and not climbing a mountain grade, the temperature was always under 170F. But towing on a steep mountain, and it would get warmer.
If you are worried about the fluid level, then cralw under the RV when it is level and remove the oil filler plug. You should have a small amount of fluid come out, or putting in your finger, the oil level should only be 1/8" or so below the plug. By the way, that oil STINKS! I have changed it out before.
You might want to go to a quick lube place and have them remove the drain plug and refill it if required. You might have synthetic oil in there.
Money can't buy happiness but somehow it's more comfortable to cry in a Porsche or Country Coach!
if there's no drain plug you can get a thing that looks like a big grease gun with a hose on it that's used for sucking out the old oil from it ,why they don't put drain plugs on rear ends anymore I don't know ,you can remove the back cover if you need to but its a pain to do and messy.130 is not hot for a rear end.
1985 Class A Holiday Rambler Imperial 33 +1979 Class C Holiday Rambler Statesman 1000 = 24 ft
Have you calibrated your IR thermometer for emisivity? Otherwise the temps don't mean much. Suggest you use it for comparison more than actual temps unless you calibrate to something like flat black spray paint.
found this out on the web:
"What is emissivity, and how is it related to infrared temperature measurements?
Emissivity is defined as the ratio of the energy radiated by an object at a given temperature to the energy emitted by a perfect radiator, or blackbody, at the same temperature. The emissivity of a blackbody is 1.0. All values of emissivity fall between 0.0 and 1.0. Most infrared thermometers have the ability to compensate for different emissivity values, for different materials. In general, the higher the emissivity of an object, the easier it is to obtain an accurate temperature measurement using infrared. Objects with very low emissivities (below 0.2) can be difficult applications. Some polished, shiny metallic surfaces, such as aluminum, are so reflective in the infrared that accurate temperature measurements are not always possible.
Five Ways to Determine Emissivity
There are five ways to determine the emissivity of the material, to ensure accurate temperature measurements:
Heat a sample of the material to a known temperature, using a precise sensor, and measure the temperature using the IR instrument. Then adjust the emissivity value to force the indicator to display the correct temperature.
For relatively low temperatures (up to 500°F), a piece of masking tape, with an emissivity of 0.95, can be measured. Then adjust the emissivity value to force the indicator to display the correct temperature of the material.
For high temperature measurements, a hole (depth of which is at least 6 times the diameter) can be drilled into the object. This hole acts as a blackbody with emissivity of 1.0. Measure the temperature in the hole, then adjust the emissivity to force the indicator to display the correct temperature of the material.
If the material, or a portion of it, can be coated, a dull black paint will have an emissivity of approx. 1.0. Measure the temperature of the paint, then adjust the emissivity to force the indicator to display the correct temperature.
Standardized emissivity values for most materials are available (see pages 114-115). These can be entered into the instrument to estimate the material’s emissivity value."
I do have a drain plug and will crawl under there tomorrow and check the level.
I'm doing the second drain of my automatic transmission fluid change then also.
I don't like to have stuff done at shops as I never know if they did it right or even did it at all. I've seen that pump thing and think I'll have to refill the rear end that way with synthetic...probably Mobil.
As far as levels on the GMC trucks the level was actually supposed to be down about an inch or so. And I've seen discussions where they said replace the rear oil after the first 1000 miles.
OLD DOG the info on emisivity was great. I've always wondered how to calibrate my IR gun. I've shot the outdoor temp gauges I have and it was close to what they were reading.
I'm thinking boiling water is always the same temp, 212 degrees at sea level, and I've shot the pan but didn't know if it was measuring the actual pan or the boiling water in it.
I would guess boiling a black stick for 15 minutes would be a good experiment.
I use my IR mainly to compare temps on my tires and it doesn't have to be right on, I'm just looking for a large difference between tires.
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