Adding Transmission Temp Gauge Sensor

[The_Handier_Man1]

From: 8BallManager  (Original Message)
Sent: 1/5/2006 12:13 AM

I'm replacing the gauges in my '72 Chieftain (413 engine) and I would like to add a transmission temp gauge.  I was thinking of putting the sensor in place of the cap of one of the pressure test ports.  Does anyone have any experience with this approach?

Thanks in advance,
Steve



From: ClydesdaleKevin
Sent: 1/5/2006 2:55 PM

I haven't added a temp guage to mine yet, but this is how I would and will eventually do it:  Park the rig on a level surface and get under it.  Using a peice of chalk or marker, mark the lowest point on the transmission belly pan...you know, the pan you have to remove to change the fluid and filter, and adjust your linkage.  Ok...remove the pan.

Take it to a machine shop and have them solder in a bung at its lowest point, using a threaded bung that is compatable in size to whatever sending unit you are using.

Clean/replace your filter while you are at it, and properly adjust the linkage.  Replace the belly pan.  Refill the transmission

Why do this instead of using a pressure hole?

Well, first, I'm not sure how a sending unit would hold up to pressure, and besides, what you want to know is the temp of the transmission fluid in the pan.  You might tap into a pressure line that is coming from the cooler, or on its way to the cooler, and not get an accurate mean temperature reading.

Secondly, you will now have a drain plug on your transmission pan!  This means that you can change the fluid easily, say every other oil change, by just removing the sending unit!  This will greatly increase the longevity of your transmission, just as frequent oil changes increase the life of your engine. 

This doesn't mean you should neglect the service manual's recommended intervals for completely draining your fluid and replacing it, accomplished by draining the torque converter, nor does it mean you should neglect proper filter cleanings/changes or adjustments to the linkage.  But it DOES mean you can maintain the transmission easily in between...AND have a sending unit location that is perfect for keeping an accurate mean temperature of your trannie.

Kev



From: denison
Sent: 1/5/2006 3:50 PM

My tranny oil temp sensor uses a 1/8th pipe thread. I brazed the 1/8th female p.t. fitting into the drivers side rear corner of the oil pan, as that seemed to be where it would not interfere with the valve body or filter. It is handy to have the 'drain plug'. The the oil temp gauge has told me a lot about the stress my tranny sees.
I later added an aux. tranny oil cooler, in series with and before the tranny fluid would go through the original tranny cooler in the bottom of the radiator. This was because I was going to be towing cars or a car-hauler trailer behind the RV. In cool weather I cover the tranny oil cooler with a piece of coardboard, so the oil gets up to about160 degrees eventually.



From: Jupp318
Sent: 7/8/2006 8:09 AM

Guys,

I'm about to fit an additional cartridge filter which comes with a temp sensor.  To do this I would like to make up some braided hoses (Aeroquip) to plumb it with but I'm not at all sure what fittings I need.  I want a pipe to go from the Tranny to the filter then another from the filter to the rad and finally one from the rad back to the tranny.

If someone could tell me the thread types for both the Tranny and the Rad I would be most grateful.

Cheers Ian...



From: ClydesdaleKevin
Sent: 7/8/2006 9:34 AM

I can't help you much there, Ian...although I'm guessing the threads are standard and not metric...lol.  When I added a transmission cooler, I had to actually cut into the lines and flare them, and use hose clamps...still holding up thousands of miles later!  On the transmission outlets, I screwed in the hose type fittings that came with the cooler after removing the old outlets...not sure what size they were, since it was over a year ago.

Kev



From: denisondc
Sent: 7/8/2006 12:37 PM

I believe the threads in the transmission case are the normal 1/8th inch pipe threads. The connections to the bottom of the radiator are either the 1/8th pipe thread, or more likely, the female of the tube fittings for about 3/16ths or 1/4 inch Bundy tubing. Also known as brake line fittings. These are the kinds of fittings on the output of the fuel pump. To make new transmission oil cooler lines, and the extra fittings to go to and from my auxillay oil cooler, I just bought lengths of the Bundy tubing with the s.a.e. threaded nuts, and the standard flare. I forget whether they were 3/16th or 1/4 inch, but they were the same size as the original tranny cooling metal lines were. They were easy to bend to shape. The old lines were badly rusted, and ready to break.
You can see my homemade metal lines at my album



From: Jupp318
Sent: 7/9/2006 8:20 AM

Thanks Guys,

I was looking for confirmation really as one of the leaflets that came with the Perma-Cool remote filter said that the temp sensor was 1/8 MPT & not NPT, as you can imagine this through me a bit.  The cooler lines I have at present are in at least 4 pieces with all manner of fittings everywhere  The Rad fitting turned out to be the same as the temp sensor thread (I tried the rad fitting in the remote filter temp sensor hole) which was said to be 1/8 MPT!.  The filter fittings themselves are 1/4 NPT and I will have to check but I think the Tranny will probably turn out to be 1/8 NPT.  I'll check to see if I have any flare nuts that fit as that will reduce the cost of re-plumbing these lines.

Cheers Ian...