Temp sender in output line of trans question.

[Leper]

I have read about people who put a temp sender in the output line of the 518 transmissions and I am wondering how to do this. I have a Westach 1/8 sender for the gauge I already have, but I don't care if I have to buy another. What I really want to know is what the switch that is there now, does. Also, what adapters will I need to do this.

TIA

Leper

 

[Philip]

The sender that is there is a temp sender. It sends a reading to the PCM. Around 275 degrees outlet temps the PCM will drop the trans out of OD.



If you remove it you might loose OD completely.

 

[Greenleaf]

If you opt to remove it, wire it so as to void the sensor. (PCM will always believe the sensor is there and operational, thus OD will engage)



If you choose to use an adapter, you'll need a Street T.





Some say the sensor must be in the flow of the hot oil to operate, others like it to sense pan oil and some like the clamp on sensor ( to the outlet line). They all work to one degree or another.



I use the Street T as the "In Pan" method resulted in a guage that would only just begin to register on the very hottest days climbing a hill under load. Now... ... it moves right up to 160°-180° soon after I start out on a hot day.

 

[dpuckett]

So the pan vs line for temp sensors is kinda like the manifold vs pipe for the thermocouple?



I'd put it where I'd get the hottest reading. The purpose is to keep the transmission cooler, and keep it from overheating.



Daniel

 

[Leper]

I have installed a DD pan from MH and there is a sensor there. I am wanting one in the output line to see the temp of the fluid leaving the trans and I read somewhere about people using the switch as the location. I plan on leaving the switch plugged in so it will always read cool to the controller. I will secure it somewhere. Someone said that I need a 3/8 npt reducer for my gauge sending unit. Is that correct? I have a 1/8 temp sender so I need a 3/8 to 1/8 reducer, right?













BTW... . The highest my in-pan temp has gotten was 150+-. Haven't towed after the pan/sensor install. I'm trying to get the other sensor installed before I make a run to Austin in a couple of weeks.

 

[sdstriper]

I would put the OD sensor in the pan, you shouldn't have to worrry about it kicking out OD then. Put the gauge sensor in the hot out port then.

 

[Hunter4x4]

Before I drilled and tapped my transmission temp sending unit into my B&M 1 qt. transmission pan I had my sending unit in the that transmission line; I simply left the OEM sending unit plugged into the pigtrail, zip tied it up out of the way, and had absolutely NO problems. Always had OD, and no problems with any functionality.



Watcha gotta remember with the 91's for sure, and I'm 90% sure with the 92's, is that the ONLY thing that the PCM does with the temp that the sending unit sends it is it cuts out OD at 270* transmission fluid temp. The problem with that is that if your transmission temp is hitting 270* your transmission has about a 15 minute life expectancy at that point!!!

 

[Philip]

That is a full reading temp sensor. If the PCM sees a trans temp of less than 60 degrees it will not allow OD to ingage. On my 93 it does at least.



Someone unplug theirs and go for a drive and let us know if your OD still works.



We talked about this a few years back. If memory serves me right you had to throw a 1k resister across the terminals to fool the PCM with some type of reading.

 

[Leper]

That is a full reading temp sensor. If the PCM sees a trans temp of less than 60 degrees it will not allow OD to ingage. On my 93 it does at least.



Someone unplug theirs and go for a drive and let us know if your OD still works.



We talked about this a few years back. If memory serves me right you had to throw a 1k resister across the terminals to fool the PCM with some type of reading.

This is why I pay membership fees. I love the internet.

 

[dpuckett]

I remember that discussion, Philip. We never figured out why Mom's 92 will go into OD 2min after starting on a 20deg morning, 1/4mi from the house- you KNOW it isnt up to 60deg yet. Or maybe it is... ... . No matter the weather, it goes into OD at 35mph like clockwork. Maybe the sensor is bad, shorted? who knows. I can unplug it and see if I still have OD.



DP

 

[Hunter4x4]

93's might be different from 91's - but I have service manuals for both so I'll check the '93 manual later and get back to you all. I know for the 91 I had OD right from the get-go even on the coldest days with the factory sending unit hung off to the side - and you know that fluid was no where near 60*. And the FSM FOR the 91 indicates that the only thing the 91 does with that temp signal is kill OD at 270+*.



Just wondering - in the dead of winter when you drive your '93 do you have OD right away - or do you have to wait for your transmission fluid to heat up? 'Cuz I know from watching my transmission temps that stuff can stay below 60* for a while but I still have OD... .

 

[Philip]

On a cold day I have to drive about 3 miles before it gives me OD. If the temps stay the same it would always go into OD about the same place on the road. LOL

 

[JSpecht]

I just put one in a 91 in the factory loction. I just removed the factory sensor and cut the wiring and spliced it back together and installed the auto meter sender in the factory loction . Normal driving its around 180/190 deg and the hottest I had it towing a around 7,000 lbs was 240deg that was starting out on a hill in town . It has a low stall converter and a bigger cooler Does those temps seem normal to you guys???

 

[PToombs]

To show the difference between pan and line; I put an accessory fan cooler on my cousins F550. The fan switch is in the line between the trans and radiator. (fluid goes from trans to radiator, to front cooler, I added the other in from there to trans. ) The gauge sender is in the pan. When he shut it down from a drive, the gauge reads about 150*, and the fan is on. The fan switch kicks on at 180*, and off at 170*.

I thought this was a good setup, when it starts to get hot, the fan goes on before the hot oil even hits the coolers. The fan cooler gives a shot of colder oil to the pan before the hotter stuff gets to the cooler. Pulling a hill with the truck loaded and skidsteer on the trailer, max was about 200*.

 

[Leper]

That is a good idea.



My question remains though. What size is the sender, and what adapter will I need?

 

[wtfd6]

That is a full reading temp sensor. If the PCM sees a trans temp of less than 60 degrees it will not allow OD to ingage. On my 93 it does at least.

Someone unplug theirs and go for a drive and let us know if your OD still works.

We talked about this a few years back. If memory serves me right you had to throw a 1k resister across the terminals to fool the PCM with some type of reading.

Hey fellas, I am having a problem with a truck right now. Im going to try a 1k resistor and see if it fixes this one. thanks.

 

[southpaw]

pipe size

Leper I wish I could rememberthe pipe size but my memory fails me . I will try a search to find the info and if successful I will get back to you. I do remember putting a " T " and an extension, ie 3inch nipple, to clear the trans I did this to keep the stock sw and also place the sender in the same location. I used liquid pipe thread sealer and used a large electrical wire crimp ring that fit snug over the sender base attached a wire and grounded it to the frame near by just to be sure of a good ground. Three years and all is working . This mod is on a 93 auto 250.

 

[Leper]

I would appreciate it.

 

[Leper]

Does anybody know the size of the OD switch?

 

[Leper]

Anyone, anyone at all have any idea??????