2000 7.3 EB Quigley 4x4 with the Diamond Eye 4” Turbo Back Exhaust using Edge readout for Tranny Temps:
As I had mentioned in a previous post heading up the switchbacks into Sequoia my Edge Tranny Temp readout showed 237 at one point near the top. Normal freeway driving in So Cal would be around 165-180 on the Edge. In the hills or off-roading in 90-105 degree heat the tranny would fluctuate between 185 and 215 depending on how hard the engine was working and if there were hills involved.
Had a chance to take my van over to South Bay Autocare to look into a solution for lowering tranny temps. They work on an average of 1 or 2 SMBs every few weeks and I had them do a complete fluid change when I first bought my van. After the test drive Hubert used the laser temp gun to take a few readings. There appeared to be around a 20 degree difference in temp reading between the bottom of the pan and what the Edge was reading.
We believe the Edge is using the stock temp pickup sensor which another member said was most likely in the PCM located away from the bottom of the pan. Where the pan was giving a reading of 144, higher up on the side of the tranny was 165, same as what the Edge was reading. So if that ratio holds somewhat true my 237 was more likely around 217 at the pan.
After discussing options for lowering tranny temps we settled on a remote mounted Aux Tranny cooler with built in fan and possible exhaust wrap if needed. The only place it would fit cleanly and safely was near the stock battery on the frame. They did a great job on the install and added a protective shield on the bottom to help prevent debris from hitting the cooler. Hubert initially decided to hook up the new Aux Tranny cooler and fan only, by passing the stock radiator and stock aux cooler routing.
Flex A Lite Aux Tranny Cooler with Fan
Side view of Aux cooler tucked out of the way
FAIL. While I wasn’t initially comfortable with disconnecting the stock setup I am not a mechanic and Hubert has installed these before on other vehicles so I was willing to give it a shot. On the way home I took the canyon with various grades of climbing and a few stop lights to put a good load on the tranny. The outside temps were 90-100 and the tranny worked its way to a high of 228 on the edge, not good. It didn’t matter if I had the Aux cooler fan on or not. This was the closest I could get to simulate a desert outing or typical mountain drive.
Dropped the van back off where Hubert reconnected the stock rad hookup, stock aux cooler routing followed by the new Aux cooler with fan. In addition he spaced the aux cooler out a little more and wrapped from the turbo to behind the tranny with the hi-temp exhaust wrap. After driving the van for a few days through the canyon with outside temps even hotter than before, in the 100-105 range. Tranny temp on the Edge readout hit a high of 201 with the Aux cooler fan on and 208 without the fan. This is with the engine clutch fan coming on a few times as well. If it is about 20 degrees difference in the pan temps vs Edge then that would mean around 180-190 for a pan reading, well within range for those conditions. This solution should more that work.
Exhaust Wrap
What I didn’t expect was to see my EGTs go down so much from the exhaust wrap. Since the 7.3 in the van has no intercooler you really have to watch it as EGTs used to be in the 850-1000 range a lot of the time with normal driving and mild aggressive acceleration or climbing hills. Now with the wrap and same driving style it stays in the 650-900 range. I really notice a difference when getting on it a bit. Where it would jump to between 1000 and 1100 it now will stay in the high 900s. I wonder if wrapping it back to further would help more?
Since this solution wasn’t cheap my advice is to try the exhaust wrap first and see if that helps enough. I wish I would have. If not, then look into another Aux Tranny cooler with a fan and find a safe place to mount it. Although the fan does help, especially when sitting idle, Hubert is going to call the vendor and make sure it is doing as much as it should. When researching I found a lot of the truck folks used the stock 6.0 tranny cooler on their 7.3s. This might also be an option to try for some if it fits in the vans. I hope this was some help to others…
Eric
Sportsmobile (AKA Money Pit)
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