4mydogs

I finally got my mechanic to install the AutoMeter transmission temp gauge for me. He put the sending unit on the line just as it comes out of the pan, going toward the radiator/trans cooler. It is an electrical gauge that reads from 100 to 250 degrees. I haven’t had a chance to go for any really long road trip, but I did drive about 15 miles on pavement at varying speeds up to 55 mph with lots of starts and stops. I also got on a dirt road and went about 5 miles in 4WD High and Low. Back into 2WD did some wheel spinning quick accelerations, in dirt of course . The gauge never went above 100 degrees, in fact it never appeared to move except when I shut off and restarted the engine (the gauge needle rests just below the 100 degree mark). I need to do some more driving, but I wondered: is it possible that the reading is correct at 100 degrees, or is it not working properly? I can’t imagine that the temp would stay so low in start and stop traffic. I thought it would at least get up to around 130 on average.

Anybody out there with a transmission temp gauge want to tell me what their usual operating temps are?

SLC Punk

I don't know the temp, but can you take a pic of the sending unit? I want to install one..

4mydogs

Sorry, I'm kind of challenged in the pic posting department. But this link should take you to it:

http://hp.autometer.com/products/acc..._manifold.htmlhttp://hp.autometer.com/products/accessories/temperature_manifold/temperature_manifold.html

rimpainter.com

Celsius or Fahrenheit?

4x4Lamm

100 seems low, very very low.

Lamm

4mydogs

Here is a photo of the gauge. The way it's graduated, I guess the left most marking is 130 degrees, not 100? DOH!

http://hp.autometer.com/products/pro...xx/002640.html

I drove around at lunchtime with the same results as earlier. So I checked all his connections and compared them to the wiring diagram that came with the gauge. They all looked good. He grounded it to a stud on the top of the engine (I guess that is okay?). I'll let the engine cool completely tonight and see if it still goes up almost to that first mark when I turn the key on. I guess I could hook a big trailer up to her and start towing it around to see what effect that has on the reading!

4x4Lamm

To test the gauge, use the gas to hold the 4Runner on a hill. After a VERY little while, if the gauge does not budge, drive back to your mechanic. The slipping heats things up pronto.

Lamm

4x4Lamm

Also, ATF is rated for its viscosity at 40 and 100 degrees Celcious. Thats about 100 to 212 Farenheight. If that helps.

Lamm

4mydogs

I actually thought about that earlier today, but there are not a lot of hills here in the SC Lowcountry so when I got back to work I pulled up to a curb, left her in Drive and set the parking brake. I checked back after 5 minutes of that and the gauge was in exactly the same spot.

bamachem

What's the outside temp there? It's pretty cool today here, and normal operating temp should be in the 140-160 *F range. Ideally, you want to be at 140. At that point, the viscosity of the ATF is low enough for it to flow well, but it still retains it's lubricating properties without any degridation from heat. You won't get it real hot in the winter w/ cool weather unless you're on a long drive. You'll get the heat in the summer when the outside temp is closer to the operating temp of the transmission and it has a more difficult time dumping it's residual heat to the surrounding air.

4mydogs

It's 60-65 degrees. I just went outside to try something. The truck has been sitting for over 2 hours now, and when I turn the key to ON the needle moves slightly, to exactly where it was as I drove around earlier. It's getting juice, but it doesn't seem to be functioning properly. Does this sound like a wiring problem, or (heaven forbid) a bad sending unit?

4mydogs

More . . . I stopped by my mechanic's shop after work. He said that they drove it around for about a half an hour and had the same results that I observed. The put a tester on the wire coming from the sending unit and said it's working. So . . . I guess I'll just have to drive around and see. Most of my driving is local, but maybe this weekend I can get out on the highway.

4mydogs

I was looking at how he mounted the manifold and noticed that the sending unit is coming into the manifold from the top. Should it be mounted so that the sending unit comes in from below, or does it matter? Just wondering . . .

TechWrench

Off the top of my head, I can't tell you whats normal for the trans operating temp, but consider this. The trans uses cooling lines to the radiator for cooling. Every trans cooler in a radiator I have seen consists of a small diameter tube inside one of the water tanks in the radiator. Most engines have thermostats in the 195-220 range. Therefore, you would expect the water temp in the radiator to be in that range. This would indicate that if you are using the radiator water to cool the trans fluid, it must be entering the radiator at a higher temp than that, and then leaving no cooler than the water temp. To me, this would indicate that the normal operating temp of the trans is in the 200 degree range. And the time of year or outside ambient temp wouldn't have much effect on the trans temp, as much as the load being put on the torque converter. The torque converter is the major source of heat generation in an auto trans. This is why, most cooling circuits in the auto take fluid directly from the converter and send it to the radiator cooler.

4mydogs

That sounds reasonable, and I can find no technical data to refute it. However, I have looked at a few member websites, and it seems that the normal temp readings they are seeing are from 140 to 180 degrees, with spikes to near 200. My gauge has not gone above 130 so far, which is just above the at rest (off) reading. I don't know why AutoMeter wouldn't make a gauge that begins with a lower reading than that. It goes as high as 250, and by all acounts at 250 your transmission is toast. I am going to call the folks that sold it all to me later today and see if they can help.

MTL_4runner

I agree that does not sound normal for temp on tranny fluid.

Try holding against a curb like you did for a couple of minutes, then shut it off and go under the truck and put your hand on the tranny pan. If the pan is so hot you can't hold your hand on it for any length of time then it is higher than 150 degrees and thus the sensor is not reporting correctly. Try not to burn yourself while doing this either.

TechWrench

Well, after some investigation, I stand corrected (somewhat). According to the '03 repair manual, pg 05-446, the normal operating ATF temperature is between 50 - 80 degrees centigrade (122 - 176 F). But the factory temp sensor is calibrated with an operating range of -40 - 215 C (-40 - 419 F) according to the info on page 05-444. And this sensor info can be read using an OBD II scanner.

4mydogs

OK, those operating temps are in line with what I have read. Now this factory temp sensor, is that for the A/T OIL TEMP light? And (forgive my scanner ignorance) does that mean than a scanner can tell you the ATF temp at any time, or does it indicate "codes" from previous problems, like running too hot? BTW, I don't have any scanners, but I would assume that my mechanic would.

TechWrench

Yes, I would think the sensor is for the A/T oil temp dash indicator. I have not used the scanner, but from what I read in the manual, it looks like it might be a dynamic output. They seem to indicate that the AT fluid temp reading on the data list should be 80 C (176 F), after a stall test. This, to me, indicates the sensor is more than just an 'open/closed' sensor. For the sake of cost, the ECU probably constantly 'reads' the sensor output, but only triggers the dash indicator when the reading passed a certain setpoint. So, if you are asking what I think you are, it might be possible to use the existing sensor to provide an input to a guage, but I would have no idea how to do it.

4mydogs

After putting up the Christmas tree and lights all weekend I finally had some time to spend in the garage. I pulled the sending unit from the manifold and put it in a cup of boiling water, then had my wife turn the key and see if the gauge read anything. NOTHING! I will have to call AutoMeter in the morning and see if they'll send another sending unit. And we'll try again.