Transmission Tmp gauge - should I ? where?

D

dave silva

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Oct 2, 2009
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I've always had a trans temp gauge in vehicles i was working hard. Most machines get warm right before they turn into a pile of scrap. Seems like a
cheap warning that might reduce the cost.

So, has anyone installed one on the TH425? Has it been useful?

--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
Dave,

Yes, a transmission temperature gauge is a good idea to monitor tranny temps and hopefully avoid burning up a transmission. Many GMCer's have
installed tranny temp gauges. My tranny temp is monitored in the pan (ragusa). Others have installed a Tee in the cooling lines and monitor the temp
there. I had to replace my gauge this past summer. Here is a link to my pics.

http://www.gmcmhphotos.com/photos/g7225-new-transmission-temperature-gauge.html

Safe Travels,
Russell
--
Russell Keith,
1978 E2 "Harry" 403 (still carbureted), Danny Dunn Tranny, Thorley, Stock Brakes w/Remote Vacuum Brake Booster, Quad Bags, Dakota Digital Dash, 6.5 kW
Onan, Dunedin, Florida
 
Trans temp is important.
There are two ways people monitor the temp.
The one that makes sense to me is to monitor the temp of the fluid that
will enter the system, as that is considered to be important.
The other to monitor the temp of fluid leaving the trans.
This is rather a good indicator of load that is put into the trans and how
hard the convertor is working.
Hot fluid is cooled at the radiator and brought back into the pan.
Also what is important is to change the fluid frequently, as the
additives in the fluid gets exhausted from heat and when one changes the
fluid, your lucky to change about 1/3 of the total.
This topic of where to measure the temp can be very controversial.

On Mon, Jan 20, 2020 at 5:11 AM Russell Keith via Gmclist <

> Dave,
>
> Yes, a transmission temperature gauge is a good idea to monitor tranny
> temps and hopefully avoid burning up a transmission. Many GMCer's have
> installed tranny temp gauges. My tranny temp is monitored in the pan
> (ragusa). Others have installed a Tee in the cooling lines and monitor the
> temp
> there. I had to replace my gauge this past summer. Here is a link to my
> pics.
>
>
> http://www.gmcmhphotos.com/photos/g7225-new-transmission-temperature-gauge.html
>
> Safe Travels,
> Russell
> --
> Russell Keith,
> 1978 E2 "Harry" 403 (still carbureted), Danny Dunn Tranny, Thorley, Stock
> Brakes w/Remote Vacuum Brake Booster, Quad Bags, Dakota Digital Dash, 6.5 kW
> Onan, Dunedin, Florida
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmcrvparts.com
1-800-752-7502
 
Dave,

I have been very happy with my "Digipanel". It is more expensive than a single temperature instrument, but it is actually 4 or 5 (model dependent).
It is much easier for Mary because she never got it pummeled into to her the habit to do an instrument scan. I only know of once that it averted a
catastrophe, but once is good.

The temperature sensors attach on the outside of the lube oil and transmission cooler lines and it is a reliable unit.

https://www.gmcrvparts.com/product-p/gdp1.htm

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Thanks, that's impressive.

For now I am really digging the fact that all my original Stewart Warner gauges work. And they make a matching trans temp gauge that will fit right
in. I'll probably relocate vacuum or amps off the main instrument cluster.

I'm not a luddite though. I like technology. I may look at a high temp alarm for the trans.
--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
Yes, the digi panel makes a lot of sense. Flashing lights have a way of
getting one's attention, right now. I do not have one, but it might be a
worthwhile expenditure. I am a gage guy myself, I have a tachometer and
vacuum gage up high, above the dash, tucked into the v where the drivers
side of the dash pad meets the curve of the windshield. I also have a
Ragusa transmission pan with an analog temp sensor in it, as well as a
sensor in the final drive cover. That one is a real eye opener for sure. I
have 3:70 final drive ratio, and was curious how hot that sucker got. Well,
now I know, and it gives me cause to worry. Before I installed the gage, i
was fat, dumb, and happy in my ignorance. But, i am a eyes down the road
kinda guy. So, the digi panel makes sense.
Jim Hupy
Salem, Oregon

On Mon, Jan 20, 2020, 8:21 AM dave silva via Gmclist <

> Thanks, that's impressive.
>
> For now I am really digging the fact that all my original Stewart Warner
> gauges work. And they make a matching trans temp gauge that will fit right
> in. I'll probably relocate vacuum or amps off the main instrument
> cluster.
>
> I'm not a luddite though. I like technology. I may look at a high temp
> alarm for the trans.
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I use a Digipanel. My Mac dash (original opening fit) has a gauge but no sender connected. On my 'to do' list. Note that you can actually mount the
digipanel out of sight - particularly if you've already got gauges either OEM or aftermarket working. The value is in the queeper (Sonalert) which
makes enough racket to get you to look.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Here is how I added a temp prob to my trans pan. Study the pan and valve body carefully before you drill the hole. Things that you stick inside the
pan through a hole you created have to clear everything. I've had this set-up on my trans pan for 13 yrs. No leaks, no problems. JWID

Look at this pic and the next two in the album.
http://www.gmcmhphotos.com/photos/transmission-install/p3851.html
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
I'm not sure i want it at the pan. On my tow vehicles i always put it on the return line from the trans cooler. The idea being that you measire how
well you are removing heat.

Does heat in the pan tell the story?
--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
The ideal place to measure temps is where the oil comes from the torque
converter. That is going to be the hottest place you can easily get to to
install a sensor. My oil temp sensor, fitted into my Ragusa finned aluminum
pan rarely registers over 160° farenheit. So it never sees converter oil.
That goes to the cooler before it returns to the pan, so if you are having
a bunch of slippage and overheating, you will never see it on a gage. Guess
you could have more gages, in and out, etc. Somewhere there is a chart that
tells you the temps that various fluids can tolerate. If memory serves me
correctly, the synthetic transmission fluids can tolerate the most heat.
That is what I use in my Manny Tranny, along with fairly frequent oil
changes. Fluid is cheaper than transmission parts, by a whole bunch.
Jim Hupy
Salem, Oregon

On Mon, Jan 20, 2020, 2:11 PM dave silva via Gmclist <

> I'm not sure i want it at the pan. On my tow vehicles i always put it on
> the return line from the trans cooler. The idea being that you measire how
> well you are removing heat.
>
> Does heat in the pan tell the story?
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I think you want it in the pan, that's the fluid that is getting used by the tranny and then pump off hot to the cooler. If the cooler isn't getting
rid of heat fast enough, you'll start to see the pan temperature climb. just my opinion.
--
Todd Snyder, Buffalo NY
1976 Eleganza II
 
Dave,

I've monitored the temperature in the pan, and those to and from the
cooler. But I consider the pan the important one because it averages all
the others. That conclusion of mine is supplemented by the Chevrolet P-30
Chassis Owners' Manual (available at bdub.net). That formerly free, no
longer available, manual has an extensive section on transmission cooling,
including comments on heat sources and system upgrades. I highly recommend
it to everyone. Their temperature guidance, including a table of ATF
mileage life vs temperature is based on PAN temperature.

Ken H.

On Mon, Jan 20, 2020 at 5:11 PM dave silva via Gmclist <

> I'm not sure i want it at the pan. On my tow vehicles i always put it on
> the return line from the trans cooler. The idea being that you measire how
> well you are removing heat.
>
> Does heat in the pan tell the story?
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Rich,

The Ragusa pan comes with a tapped hole for the drain plug, and another for the temperature sender. Look at the top edge of the pan, above the holes
in this pic, they are labeled "sensor" and "drain".

http://www.gmcmhphotos.com/photos/data/7225/new_tranny_temp_sender.jpg

Russell
--
Russell Keith,
1978 E2 "Harry" 403 (still carbureted), Danny Dunn Tranny, Thorley, Stock Brakes w/Remote Vacuum Brake Booster, Quad Bags, Dakota Digital Dash, 6.5 kW
Onan, Dunedin, Florida
 
An external contact type thermistor sender is the only type I would consider. Plumbing in any sender adds a fail point, by the plumbing or the sender
itself spewing hot oil (fire hazard). Similar type fail to Onan oil pressure switch which is common. Since the factory used a liquid to liquid cooler,
I simply use coolant temp as a guide to trans temp.

--
John Lebetski
Woodstock, IL
77 Eleganza II
 
John, on my coach, coolant temp only shows me what temperature coolant is going into the radiator. I use the transmission temp gauge to find out what
temp is going into the transmission pump and hence the transmission works, particularly the clutches. Note that Tom Pryor has mounted a temp sensor
at the output of the radiator which activates his cooling fan. That temp is relative to the transmission cooler temperature, but the transmission oil
is probably a bit warmer.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
> I simply use coolant temp as a guide to trans temp.

I'm thinking if the coolant is entering the radiator at, say, 210F, and it's returning to the engine at 190F then you might not know if the trans temp
is climbing. Or, you won't know it until it goes past the point where the radiator can remove the heat.

For the price of another gauge, maybe i'd want to see the temp going in and going out? Probably overkill but i see transmission failure as the most
disruptive thing that can happen.

- can't see it coming

- can't get parts quickly

- can't work on it myself
--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
> Not to steer this thread a bit sideways but what is the "ideal" trans operating temp of a 26' with 403. 26' with 455 and the same for the 23'
> units? I'm not a "gauge" guy but do see some value in having this one providing i know what i should be seeing on the gauge.....

Good question, so i did a search. The broad general rule across a bunch of transmissions, according to random people on car forums is 180-210 - same
range as the engine.

And there is broad consensus that the cooler it is the longer it lasts.

--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
You actually don’t need another gauge. Just a switch. You can have a sensor going in and another going out and just switch the two sensors to the one gauge with a switch.

Emery Stora

>

>> I simply use coolant temp as a guide to trans temp.
>
> I'm thinking if the coolant is entering the radiator at, say, 210F, and it's returning to the engine at 190F then you might not know if the trans temp
> is climbing. Or, you won't know it until it goes past the point where the radiator can remove the heat.
>
> For the price of another gauge, maybe i'd want to see the temp going in and going out? Probably overkill but i see transmission failure as the most
> disruptive thing that can happen.
>
> - can't see it coming
>
> - can't get parts quickly
>
> - can't work on it myself
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
My point is since it's a liquid to liquid heat exchanger, if the Dexron is much above 260F it would be boiling the coolant in contact with the heat
exchanger in the right hand tank. Remember we only run at 9 PSI. If there is boiling you will be venting coolant to the overflow in short order and
you've got bigger issues than your TH 425.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
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