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Discussion Starter #1
Driving home to Kansas from Colorado after an off road trip and my temp is running around 220-230. I stopped and checked fluid, pulled the plug and had small amount of fluid drip out. I went ahead and stuffed as much fluid in as i could. Did not seem to matter for operating temp. Should i be concerened? Thanks.
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Not sure if having it in the fill hole will be accurate. I don't think I have ever seen a trans temp sensor that is not somewhere between the fill and drain.
 

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Discussion Starter #5
Not sure if having it in the fill hole will be accurate. I don't think I have ever seen a trans temp sensor that is not somewhere between the fill and drain.
I've often questioned the accuracy myself. I'm not sure if it is actually measuring fluid temp, radiated ambient air temp, or a little of both?
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Wouldn't the air temp inside tranny closely reflect the oil temp when operating?
Anyone know normal operating tranny oil temp?
 

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no i dont think the air temp would be the same as the oil, oil and air hold different amounts of heat and heat and cool differently. air heats and cools faster than oil so the air could be superheated by the oil. i would try that same sensor in the drain hole, that of course means your going to lose some fluid, if not all.

and i dont know the normal temps, but it would be hard to cool it since there is no pump, so one would have to be added. even though your temps were 220, i dont think that is abnormally high.
 

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I put the temp gauge in the fill plug as well. But I have not holed the gauge up yet.

While not submerged in oil at a stop, it should be real close to the operating temp. within a few degrees. Probably more error in the gauge then from position. When you are driving you have gears rolling through all that gear oil. It isn't a smooth level pool of oil. It is being churned and thrown everywhere. The oil is in touch with the case, and aluminum conducts heat pretty good. I don't see any issues with the heat conducting an inch up to the fill plug to the sender. So while the sender may not be text book correct per normal engineering methods, it will be close enough for general monitoring that you (and eventually I) will be doing.

For reference I hit similar temperatures during long fast drives in the rear axle. 220° is a great number to hit with gear oil. Warm enough to drive out moisture (boils out at 212°). Warm enough to be thin and reduce drag. Still way cool enough it is nowhere close to cooking. I start raising an eyebrow when the gear oil temps are up around 265°. Or when there is suddenly a noticeable change in trend that can't be explained by other means (weather, driving pattern, load, etc.). Come 280-300° something isn't happy. Either too much sustained load (did you remember to lower the sail on the sailboat before taking off down the interstate) or something has gone bad.

What does worry me is that you managed to add fluid on the side of the road. Unless there is a leak it should have been filled. You did check it when you put the probe in, didn't you? has any leaked out? When you filled it, how much did it take to fill it? You did this while parked level? Having to add fluid is not normal for transmissions. Bottom of the threads is the correct fill level. Don't overfill.
 
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