adding a transmission temp gauge on P30 chassis

My '84 P30 has a gauge Stewart Warner trans temp gauge installed. Upon closer inspection, it does not appear it was ever hooked up. Not much help, but I replied so I could subscribe :) I want to hook the gauge up but I'm not sure how or where to get the temp reading from.

They make various sensors that can be screwed in to an outlet on the transmission sump or can be inserted in to a "T" in the cooling line going from the transmission to the radiator. The best place is at the output from the torque converter but as an aftermarket addition, either the sump or the cooling line are the only choices. These may not give the hottest fluid temperature but it will show an increase in temperature so that you can do what is necessary to lower the temp. Places like Summit Racing and Jegs online have various sensors and gauges that can be adapted to most transmissions.

I installed one on my 1989 Pace Arrow P30 chassis. I removed tranny pan to check clearance inside. Drilled hole while pan was off. Welder welded nut to pan. Screwed gauge into nut using permatex sealer. Worked great. While I had pan off drilled 2nd hole and 2nd nut welded to use as a drain. I could then drop an empty pan. You must drop pan to check clearance because it is pretty crowded inside tranny.

Thanks for the reply, I would think the sump would give the most accurate reading of what is going on in the tranny, I'll have to look to see if there is anyplace to mount a sensor, if not I guess it will have to be on the cooling line.

WyoTraveler wrote:
I installed one on my 1989 Pace Arrow P30 chassis. I removed tranny pan to check clearance inside. Drilled hole while pan was off. Welder welded nut to pan. Screwed gauge into nut using permatex sealer. Worked great. While I had pan off drilled 2nd hole and 2nd nut welded to use as a drain. I could then drop an empty pan. You must drop pan to check clearance because it is pretty crowded inside tranny.

That looks like a good solution, I may try that when I change fluid, Did you use synthetic transmission fluid? Did you ever have a problem with the tranny overheating? Maybe I'm being paranoid, My last MH was a pusher with an Allison transmission so I let the computer worry about it
By the way, I went to high school in Byron, you're probably on the other side of the Big Horns from there.
Thanks for the help
Jerry

sesspool wrote:
That looks like a good solution, I may try that when I change fluid,

I think I'll do the same unless I locate a pre-installed sensor somewhere. It's odd that the gauge is there but not hooked up. Looking behind the dash, it looks like it's supposed to be there (installed by Tiffen). I don't like the way the fluid looks so I'm going to change it anyway.

When I looked into this I found that there is a test port that you can hook into, on the drivers side just above the pan. My P-30 has a 4 speed, it may be different on a 3 speed.

I installed this one last year on my 94 P-30... Works good and I bought it so when I pull long mountain hills I can see how the trans is doing.. http://www.amazon.com/Auto-Meter-2640-Transmission-Temperature/dp/B00062YWBU/ref=sr_1_4?ie=UTF8&qid=1404961657&sr=8-4&keywords=transmission+temperature+gauge

There is some discussion of the best location to mount it. My previous trans had factory installed sensor in the pan. (BTY: the designer raced competitively in F1) The reality is that a sensor in the pan will be "good enough". The internals in the trans heat up over time. You don't need a peak reading to know the trans is getting hot. The second reality is, if you are getting too hot, what are you going to do? Run in a lower gear, so there is less slip. This brings the temp down slowly, just as the rise in temp is slow. Is a sensor in the line going to tell you there is a problem sooner? Not really, because the rise is slow enough you will see it anyway.

I would also suggest that most of the time when the trans overheats, it is under conditions where the engine is putting out a lot of heat as well. In other words, most of the time, the root cause of a trans getting too hot is because the engine is hot and working hard, so the trans cooling from the radiator does not cool the trans enough. (that is why the trans has an extra cooler after the radiator.)

Basically if you can cool the fluid, the trans will stay cool enough.

As an additional note, the 4L80e has the internal sensor right after the pump, which means GM thinks monitoring the pan temp is all that is necessary for the computer to make alternate decisions to save the trans.

It doesn't hurt to put it in the cooling line, but the pan is good enough.