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Transmission Oil Temp
I have a 8V92 in my 1992 Prevost my coolant temp runs 190 to 195 degrees but my transmission oil temp runs from 195 up to 210 to 220 degrees on long stretches is this normal operating temp or is my sensor acting up. When I slow down or come to a stop with high idle it drops down under 200 degrees. -
10 Replies
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It is possible the temp of oil is not crankcase oil, but transmission fluid temp.
Typically the HT755 transmission paired with the 8V92 tracks the engine coolant temp reasonably close. In rain it will run much cooler. When overfull it will tend to run hot due to foaming.
Start by verifying what it is the gauge is measuring. Then if it turns out the gauge is in fact measuring transmission fluid temps try to note the temps and when you see those temps. Pulling a long steep hill with a heavy toad would explain higher operating temps but so would overfilling. Seeing a substantial drop from normal temps which are likely close to the engine temps would be from a long downhill or heavy rain.
If the engine temps are also getting into the 200’s you might want to look closely at the radiator condition.
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Thanks Jon the gauge on the dash is the transmission oil temp so is 200 to 220 degrees normal operating temp or is that getting to hot do I need a transmission cooler or will I be fine. -
I don’t know the details but my gut suggests that high a temperature for the transmission fluid seems too high.
Its been a long time since I had mine so I can’t be sure of the details but I believe the transmission temps were about 20 degrees lower, with only a little increase in temp when pulling a long steep hill, and as soon as back on more level ground the temps were below 200, maybe in the 180 range.
Have you changed fluid, or has any fluid been added? Those temps could be associated with overfilling.
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I have owned the Coach for a year not sue if the previous owner did a transmission flush so maybe I will get that done what oil do you recommend to use in that transmission. I see you guys are talking about this issue in general discussion so that answer my question then on transmission temps and what oil to use. Thanks for the input. -
When I had my 94 8v, Detroit told me not to change to Transynd, stick with Dextron.
You’ll probably hear different opinions, I did what they said.
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my 8V92 paired with the HT755CR tranny runs less than 170 on a cool day and pretty much tracks with ambient air once the outside air reaches about 80. In others words today running up I-95 with 90 outside I was less than 180. I have only seen 195 once and that was when I cut a belt and lost the radiator fan.
my tranny oil temperature tracks the water temp so less than 180 in the heat of the day today. The only time I have seen more than 200 was when I had the tranny locked in first gear high jakes on going down a very curvy mountain road.
Use the transsyn. Pricey but it does run cooler. It will take a couple of fluid and filter changes to get it converted over (say 10,000 miles apart) but worth the money and effort.
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O’m not aware of a transmission flush, but if you do opt to go with Transynd spec fluid, as Joe says do a change and then in a short time, do a second change. Given the history of maintenance I would insure the internal filters are also changed. Be careful when restoring the oil pan and observe the torque specs.
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DEFINITELY transsynd or a similar full synthetic. As I recall, the 755 has an external oil filter.
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It has internal and external filters.
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Hey Jon I changed the oil and filters on my transmission they put Transynd oil in it and the two hour drive home from the truck shop she never got over 185 degrees . So temp problem taken care of thanks for your guys input.
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