Update!
Good news and bad. And, a theory.
Randy finished the prototype install of my TCI hi-cap transmission pan (pn 378000) and the super efficient Derale stacked plate cooler (pn 13401).
He mounted it in the space behind the grill bars and in front of the AC condenser. He disconnected the factory tranny cooler, secured the rigid factory lines properly, added the correct (beautiful!) fittings for stainless steel braided line (6AN fittings), and made up custom length stainless lines to and from the cooler.
He ran into significant problems with the TCI deep pan. NOT where you would expect problems. No problem getting it physically in there, BUT one of the 2 sensors had to be removed (carefully!! They break very easily!!!) and the pan, pn 378000 as shown earlier in this thread, which is specifically suppsoed to work with either a 700R OR 4L60-E transmission, would not mount because the transmission filter hangs down too far and hits the standoffs cast ibto the pan (which were cast there specificallly to support that filter!). Randy called TCI, and they admitted that a different filter must be substituted, and gave Randy the part number. After a 45 minute return trip, Randy discovered that this new filter was ALSO incorrect, as the filters came in two diameters, and the part number given him by TCI was the wrong one. So, a nother trip to the autosupply. The 3rd part number filter did fit.
Draining the tranny without a flushing machine (I don't have one
) got 5 quarts out of the transmission (holds 11 quarts total). We replaced that with 7 quarts of Amsoil Universal synthetic (do NOT use Amsoil's OTHER "racing" synthetic transmission fluid - it won't work with GM Dexron III already in the transmission). Notice we needed 7 quarts, not 5, because the new pan holds 2 extra quarts.
No leaks!
We then went on a purely scientific "road test", where any fun was purely for the sake of scientific research. Randy drove.
It ws 95 degrees in Austin at the that time of day. We did 30 miles or so, in suburban highway traffic (50 mph and 60 mph speed limits, traffic lights, and one 16% (yes, SIXTEEN percent) prolonged grade.
The transmission fluid temperature guage got to 200 after a few miles and STAYED there. WE got it to reach 210 after the 16% uphill grade, and after a couple of exuburent bursts of acceleration (two of us aboard remember) from 20 to 70 mph.
The needle never went above 210, whereas before it would hit about 235 under similar conditions.
But .. .
I went out in traffic again later to run some errands. At city speeds, that guage never got above 210, but on the other hand, it never got below either! It just stayed there.
Then, I did some hill country acceleration blasts just outside the suburbs. Now remember I am ALONE at this point, not with 2 of us in the SSR anymore. I got the guage to hit the "0" in the "210" digits. so maybe 220 degrees actual. Never went any higher, BUT also never returned to 210 after those blasts.
What was even more interesting was that since I was watching the gauge closely today after the install, I saw something that verified what I THOUGHT I had been seeing in previous weeks, randomly. Sometimes, after a re-start of the ignition, the gauge would simply not regiter any temperature -even though it swept the face like normal on start-up. I had the gauge cluster replaced recently because of this random occurence!
Evidently, the gauge replacement did not solve the problem.
I think I know why.
It's not the gauge that is not working randomly. It is the transmission temperature sensor.
Randy and I looked it up in the Helms manual.
Do you know WHAT it is? It is a simple and probably cheap THERMISTOR (electrical resistance changes with temperature).
Do you know where it is located? It is fastened to the bottom of the valve body in the transmission. It is NOT in the pan, and it is NOT in the return fitting. It is fastened to a HOT internal transmssion part. Randy studied the schematics for the transmission, and cannot tell from them if it is even in the "river" of fluid flow through the transmission or in a "sheltered tributary" where the flow may not be exactly high volume.
My new theory is that this stupid sensor unit is:
1. heat soaked because of its location in metal mass versus in the fluid, and therefore slow to cool back down after any exercise of the transmission
2. prone to stop sending any signal at all at times
3. Not necessarily a good indicator of overall transmission thermal stress
I am pissed about this.
Randy tells me that it is not typical for street vehicles to have transmission temperature gauges from the factory. The general aftermarket approach is to install temperature sensors in the return fittings in the line from the cooler, or in the pan. Both approaches would give you the FLUID temperature as opposed to metal temperature and BEFORE it is run through the tranmission. If what Randy says is correct, the approach that GM has taken therefore gives us something different and NOT comparable to aftermarket readings.
What I mean by that is that the 200 or 210 degrees I am seeing on the gauge is NOT the temperature of the pure fluid, but rather the temperature of the metal plus fluid valve body environment that the GM sensor is fastened to.
I have no idea how that compares precisely to the temperature of the fluid in either the return line from the cooler or in the pan, but I'm sure it is HIGHER than either, since the whole point of the fluid is to be a hydraulic transmitter of pressure AND an agent to cool down the parts it is going through! Both activities would heat up the fluid way above is pan or return line temperature.
And, the fact that the sensor is unreliable (like the damn cooling fan), is just another irritation on what is mostly a neat vehicle.
How are we supposed to fix THAT problem?
Even if GM gives me a new sensor under warranty, if it is the same crap as the current one, what's the point?
And, it is unrelaible, what assurance do we have that it is ACCURATE, even when working?
As you can probably tell, I am not delighted with what I have apaprently learned.
As for the experiment, well I appear to have shown that we can reduce the heat spikes on our transmission by adding a true external cooler, but we really don't know what the true temperature of the fluid is.
And, the true temperature of the fluid IS important, because fluid kept below 170 degrees last maybe a 100,000 miles, but fluid allowed to spike to 210 or 235 loses life at the rate of HALF of the life per 10 degrees of increased average temperature.
Once again, another SSR "quirk".
Jim G
