Mounting Sensor in Tranny Pan

TeryT

TeryT

New member
After a good amount of research (the details of which I won't get into here unless asked), about the only way I can mount a temperature sensor - to measure fluid temp in my V8's tranny - is to mount it in the trans fluid pan.

A local machine shop will braze a nut on the pan for the sensor to screw into for $35. Local Toyota service says there is no issue unless it leaks. Machine shop said they will guarantee it won't leak.

Thoughts?
 
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TeryT said:
After a good amount of research (the details of which I won't get into here unless asked), about the only way I can mount a temperature sensor - to measure fluid temp in my V8's tranny - is to mount it in the trans fluid pan.

A local machine shop will braze a nut on the pan for the sensor to screw into for $35. Local Toyota service says there is no issue unless it leaks. Machine shop said they will guarantee it won't leak.

Thoughts?
Click to expand...

Yeah, why??? Why risk a catastrophic failure from a leak for a temp reading that doesn't matter (because you have a cooler?)
The only reason I can see for being concerned with this temp is if you are doing severe towing, in which case just put the $35 towards a bigger aux. cooler.
I'll ask. What's your research?
 
I dont know if it is worth it. The transmission has an overheat warning light, while not nearly as good as actually having a gauge probably good enough. Consider the fact that engine oil pressure probably more critical and we only have a light for that as well, a light for tranny oil temp should be fine.
 
Re: Re: Mounting Sensor in Tranny Pan

Kmvreter said:
Yeah, why??? Why risk a catastrophic failure from a leak for a temp reading that doesn't matter (because you have a cooler?)
The only reason I can see for being concerned with this temp is if you are doing severe towing, in which case just put the $35 towards a bigger aux. cooler.
I'll ask. What's your research?
Click to expand...
Well, before you can determine if something needs adjustment, you have to establish a baseline; to wit, how can you know if you need that bigger cooler?

Yes, I plan on doing serious towing, and over on RV.net there are many, many, many discussions on this same subject. Man we have beat on this horse a lot!! Transmission overheating-related failure is most probably the biggest issue when doing substantial towing. By the time the idiot light has come on, which is set at a very high limit, you have likely already cooked the fluid.

There are a lot of reasons for wanting to know if your fluid temperature is going up or down, so that you can affect things like your speed, the gear, the weight, etc. - or perhaps pull over & let things cool before damage is done. No other indicator (water, oil, etc.) is as important to know, as tranny fluid temp, when pulling a long, hard, Arizona hill (several thousand foot elevation gain) in the summer at 110 degrees.

Now as to the location of the sensor, the single best place is in the output from the tranny to the coolers. This is where the fluid is the hottest. And it is the fluid temp that needs to be paid the most attention to, as this is what is susceptible to the heat & breakdown. But, the sensor for the particular gauge I wanted to install, is a little long, it seems, to fit in a made-up manifold block to go in the supply line. I spent many hours fooling with NAPA people, import shop people, brass fittings, and on the phone with suppliers. Therefore, the next best place to put the sensor seems to be in the tranny pan. Many others have done this.

Now the tranny pan probably won't give me the highest fluid temps, like in the discharge line, but it will show me trends. And will give me plenty of heads up, should the temp be getting up there.

I will take the pan off & take to the machine shop. It will be kept very clean, and receive a final cleaning with microfiber before reinstalling. The open transmission (minus the pan for a few hours) will be sealed with something (celephane wrap?) so as not to attract dust.

Thanks for asking. Let me know if there's something else I am forgetting!
 
If you really want to do it, why dont you tap into the cooler lines going out. Should be much easier to do than a hole in the pan??
 
A trans temp gauge is the best way to keep track of what's going on with trans during towing. I would suggest a gauge that also has an idiot light to indicate you are reaching a critical temp, BEFORE it reaches a damaging temp. (If there is one)

I would think that the location for the sensor would be best placed where the supply fluid is going into the trans (at the pick-up, in the pan), not at the hottest point.

You may want to check and see if your trans uses the new Toyota fluid. I think if you have a sealed trans (no dipstick) you will have the new fluid (if I'm not mistaken it is synthetic). If your trans is using regular fluid, the most effective trans saver would be to change to synthetic trans fluid.

Koz
 
I've participated in so many discussions on placement of the sensor! Right now I'm just settling for what works. (As far as placing it in the line - the prefered place, please see reasons stated in message above - it's become a bigger pain to do it that way! So in the pan it goes.)

It does not have the new "world" tranny fluid, and is not a sealed system. I've had numerous people, including several at Toyota, tell me the T-IV my 03 uses IS synthetic! Even called Mobile 1 on this, and they said they don't have a synthetic replacement. If there's more current info that's different - I'D LIKE TO KNOW!

BTW - The guage is digital & also has alarm settings in it. That's one of the reasons I selected it, and can't change the sensor to something that might work being placed in the line.
 
How doe the overheat light operate?

Does the ECU monitor/read the tranny temp, or just a threshold value?

Any way to monitor it with a scan tool?
 
Amsoil makes synthetic ATF which is a suitable replacement for T-IV Toyota ATF. I will probably flush mine with it later this year at the 40k service.

I dont believe the T-IV is fully syn, otherwise why woudl they change to the new WS. With WS they could seal up the transmission and claim it is life time. SO WS is probably full syn, but I still dont like the lifetime claim.
 
Bluto said:
How doe the overheat light operate?

Does the ECU monitor/read the tranny temp, or just a threshold value?

Any way to monitor it with a scan tool?
Click to expand...
Are you asking about the stock idiot light or the gauge I'm installing? Don't know anything about the idiot light. The new gauge monitors temps, and allows the user to program alarm limits. At an alarm, the normally steady red LED flashes.
 
bulldog-yota said:
Amsoil makes synthetic ATF which is a suitable replacement for T-IV Toyota ATF. I will probably flush mine with it later this year at the 40k service.

I dont believe the T-IV is fully syn, otherwise why woudl they change to the new WS. With WS they could seal up the transmission and claim it is life time. SO WS is probably full syn, but I still dont like the lifetime claim.
Click to expand...
I asked the same questions of a Toyota dealer tranny tech, and just got sort of a dumb look!
 
TeryT said:
I asked the same questions of a Toyota dealer tranny tech, and just got sort of a dumb look!
Click to expand...

Terry I think bulldog-yota is right about your fluid NOT being synthetic. You should find out for sure because changing to synthetic would make a BIG difference in cooling/protecting your tranny.

That digital guage with a programable alarm sounds great.

Keep us informed, I'm sure other members will need this info if they plan on towing seriously.

Koz
 
TeryT, thanks for sharing all the information you've uncovered.

I like the idea of knowing the actual temp, instead of just waiting for the alarm light. It would be really nice to know (and the op. manual doesn't say much about) what kind of operation and condition boost temp and what doesn't. It seems like that's the best way to learn how to tow with the least stress on the 4Runner.

After you get the sensor installed, please post again and let us know what you learn, even if it's initially from normal driving conditions.
 
TeryT said:
Are you asking about the stock idiot light or the gauge I'm installing? Don't know anything about the idiot light. The new gauge monitors temps, and allows the user to program alarm limits. At an alarm, the normally steady red LED flashes.
Click to expand...

The idiot light. The ECU recieves a signal to turn it on from something. The 4Runner has some type of transmission temp probe stock.
 
Koz said:
Terry I think bulldog-yota is right about your fluid NOT being synthetic. You should find out for sure because changing to synthetic would make a BIG difference in cooling/protecting your tranny.

Koz
Click to expand...
I called Toyota too, and was never confident of whether T-IV was synthetic or not. Like someone on another thread said - for synthetic, it's the cheapest around!
 
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