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1989 700R4. I was just sitting in park for a while at my daughters school waiting to pick her up and the coolant temp made it up to 230 and the fans brought it back down to the low 220's but my trans temp gauge that I just installed showed the temp going up to 220 and staying there even once we started driving on the highway at 70 mph. It is 85 degrees today here in the Nashville area. I thought the trans temp should never get about about 175 (from all the varying answers found through search). Trans fluid is clean but could probably use a change. I've only driven the car a few times with the new trans temp gauge (sending unit in the test port) and it hasn't gone above 160-170 but it was cooler air temps then.
I've been thinking about getting a cooler as I've discussed in other threads, but wondered if this is a normal temp for a stock 700R4 using only the radiator trans cooler. Thoughts?
In my opinion 200 and higher is too hot, but I have no idea what a typical c4 runs at. My truck stays under 150 unless I am pulling a heavy load and then it might hit 190.
..... The factory trans cooler is built into the radiator side tank ... trans temp will likely mirror engine temp ... less a few degrees for the outlet side of the radiator .....
I've been thinking about getting a cooler as I've discussed in other threads, but wondered if this is a normal temp for a stock 700R4 using only the radiator trans cooler. Thoughts?
You are good. Trans temps fluctuate and remember that the fluid gets cooled by the radiator, so your trans will mirror the radiator at a point.
You aren't reading fluid temp at all. That port has no flow past it. It is a dead-end. You're reading the temperature of the case, which is influenced by the proximity of the exhaust. Any evaluation of "fluid temp" based on readings at the pressure port are invalid. The cooler is in the 'cold' side of the radiator which can be quite a bit colder than coolant temp. Corvettes don't weigh much, nor have any towing capacity, so with a stock torque converter don't produce much transmission heat. I highly doubt your trans fluid temp is 220 deg on an 80 deg day. Your gauge is wrong.
The sender should be in the pan. That's where the OEM's put it on millions and millions of vehicles. In the pan, so it reads fluid temp.
Good catch, i did not see where the gauge was located, I assumed the pan.
See note about alternate sending unit locations and the recommendation to use the test port on a 700R4. They state that the alternate locations will also give accurate readings vs in the pan.
I don't have pre-cats. While the instructions I posted did say the pan is most accurate, the instructions that came with mine only stated to use the test port. With the fluid being cooled by the radiators built in trans cooler I could see the temp matching the coolant. I'm just wondering if that is normal. Regardless I will add an auxiliary cooler.
04-13-2017, 04:34 PM
Trans Temp Too Hot?
