Tranny temp gauge for 2000MH

[GAGypsy]

Have Scan GuageD but it does not read tranny temps on 2000MH Allison! Has anyone figured out a way to get tranny temp without tapping the pan or buying a pan with tap in it?

[1ciderdog]

On an older RV I used to have I added a T fittings in the hot line out of the transmission and put the sensor in that. Worked OK.

[edgray]

Originally Posted by GAGypsy

Have Scan GuageD but it does not read tranny temps on 2000MH Allison! Has anyone figured out a way to get tranny temp without tapping the pan or buying a pan with tap in it?

Have you verified that with Linear Logic? The reason I ask is because I know the SG II used on gassers can read the 2000 series 5 speed tranny temp, but cannot read the temp on the six speed versions of the 1000 or 2000 series. Something about Allison changing the "language" used and LL not being able to crack the code.

[charles tuit]

Originally Posted by edgray

Have you verified that with Linear Logic? The reason I ask is because I know the SG II used on gassers can read the 2000 series 5 speed tranny temp, but cannot read the temp on the six speed versions of the 1000 or 2000 series. Something about Allison changing the "language" used and LL not being able to crack the code.

I worked with Linear Logic several years back to try to get trans temp on my diesel MH2000 5 speed. From what I understand it works on some of the 5 speed gassers but haven't heard of diesel MH 2000 reading the trans temp.

If anyone with the diesel MH 2000 has temp readings please let us know.

[edgray]

Originally Posted by charles tuit

I worked with Linear Logic several years back to try to get trans temp on my diesel MH2000 5 speed. From what I understand it works on some of the 5 speed gassers but haven't heard of diesel MH 2000 reading the trans temp.

If anyone with the diesel MH 2000 has temp readings please let us know.

Charles, You may be right. I did not know that there was any difference inside the same series tranny just because of the fuel burned by the input power source. Maybe it is because of different "language" spoken between the TCM and ECM, I really don't know.

I do know that OEMY arranged for a 6 speed gasser tranny to be available to the engineers at LL, and they were unable to crack the code spoken by the newer 6 speed Allisons.

FWIW, I think your last line appeal may be the only hope we have about this.

[dbarton291]

A little Friday food for thought.

The transmission temperature broadcast on J1939 is a readout of the sump temperature inside the transmission. That is what hardware like the Scangauge does. It displays what is being broadcast on the J1939 CAN bus.

That is a good number to know, but the hottest point in the transmission system is the to cooler port on the transmission. That is the point at which trans fluid exits the transmission (after the torque converter which is the greatest source of heat even when in lockup) and goes to the cooler. The temperature in the sump is after the fluid has already passed through the cooler.

A simple fitting and temp sensor at the to cooler port, connected to a gauge will let the operator see the worst case for the trans fluid temp. The so what of this is you can see if the trans fluid temp ever exceeds 300 degrees F and know if the trans fluid is degrading. Monitoring temp at the to cooler port lets the operator know this much sooner than seeing a sump temp readout. You can have in excess of 300 at the to cooler and if the cooler is operating well the sump won't hit 300.

Just food for thought. I know it's probably a lot cleaner looking to have just a Scangauge in the vehicle and not having an additional trans temp gauge mounted somewhere.

I'm not sure why the Scangauge doesn't read on all installations. There's really no difference in the J1939 broadcast messages from gas or diesel. It's an SAE standard.

[Civdiv99]

Re dbarton291

I definitely agree. I'd given this a lot of thought in dealing with a different vehicle when dealing with temp issues.

But, like my MH's Allison, that vehicle's ZF trans monitored and reported in-sump temp via sensor integrated with the harness, and similarly would trigger a diagnostic if over temp.

Come to think of it, it also calls for a specified fluid spec generally priced via the unobtanium market as well.

I started thinking that the similar temp monitoring approach of the 2 otherwise completely different mfr might be two fold - 1) the sump represents the fluid temp on the way in to the trans; the current use temp if you will (friction and viscosity characteristics seen by the trans are impacted by this figure, and in my ZF application, trans logic is affected by cold temp as well as a hot condition), and 2) as a system the effect of the cooler may be considered to the extent that "if the sump is x degrees, then holy crap it must be damn hot on the way out the port."

I had mostly minimized my consideration #2 because like with Allison, that basic ZF trans series is used in a lot of different end mfr applications, so good vs poor cooling is going to end up quite a variable, yet the overall concept remains valid.

Maybe a question for forum member Tom Johnson regarding considerations of the fluid temps. I know that like the Transynd specs, the unobtanium fluid that ZF specifies is very robust in terms of tolerating high temps in terms of viscosity and oxidation effects, and accordingly is also a long-drain fluid.

But my curiosity of my output temp remains........