Hey guys, this is my first post on the V10 forum. I originally posted this on the Excursion Forum thinking I may have a bad scan gauge or temp sensor. Some are thinking I may have issues with the tranny itself. A couple posts mentioned that tranny discussions come up often over here so I am looking for a little more help. Here is the link to the thread fi anyone wants to check out any info/ideas that have already been suggested.

https://www.ford-trucks.com/forums/9...gs-be-off.html


This past summer I installed a scan gauge 2 in my X. Over the past couple of months I have started to question the accuracy of my readings. It started this summer when I was getting tranny temp readings that averaged around 202-205 while towing a 6,000 lb TT through flat terrain in Minnesota. It seemed most gas owners were reporting running in the 180 range with much heavier loads. I also questioned the MPG whenever I let my foot off the throttle. My readings would often say 9999mpg. Two weeks ago I flushed the tranny and put in Mobil 1 tranny fluid. This past weekend, I towed a 9,000-10,000 lb load (it was a 14' high fish house, so it did have a lot of wind resistance) 220 miles in 40-50 degree temps. My coolant temp ran between 180-187 for the whole trip according to the scan gauge. After 30-40 minutes my tranny temp reading on the scan gauge was running between 220 and 227 degrees. I thought I had read that at 220, the factory gauge would rise to the caution level. I found that my factory gauge would not rise until it hit 228. At which point it would move just enough to cover the top of the circle under the needle. I have also noticed during the past couple of weeks that I have a difference between my coolant temps and my tranny temps when I start the vehicle up in the morning. Sometimes it is a 10 degree difference, with the tranny temp being cooler. Shouldn't these temps be the same after sitting 6-8 hours in 40 degree temps. I have also had differences when the vehicle has sat for a week or more. Does this sound normal? Could I have a defective scan gauge, or is it possible the sensors in my computer are giving bad readings?

 

Don't know if this will help, but with the ScanGauge 2, the most I've ever seen my trans temp at was 155 degrees, towing 3,000 lbs, on a 90 degree day, through suburb traffic around 3 PM. I think you might have a bit of an issue, but others may have something to say, and they might know a bit more too.

 

Something definitely doesn't sound right. They should be the same temp when you first startup. When the scan gauge is reading 200, get one of those point-and-shoot themometers with the laser pointer in it, and check the temp of the tranny pan. It should be the same as the scangauge, or at least, within 10 degrees, I'd think.

 

That's accurate. The PCM will shut the injectors off when coasting so the engine isn't using any fuel at all. The computer sees the distance increasing, but using ZERO fuel. That's REALLY high mileage.

Are you certain the trans isn't overfilled? If the level is even a little bit too high the rotating parts in the trans will whip the fluid into foam. All this whipping of the fluid can make it HOT.

You could have a sensor problem. Checking it against something else like Krewat suggested is a good idea.

 

I can check the fluid level tonight. I would hope the shop that did the flush would have checked the level before sending it out. However, I did seem to run a little hotter than other this summer when I had the old fluid in. I would like this to be the case as it sounds like the easiest fix.

I will get a heat gun from the fire station this weekend and see if I am getting different readings.

 

I also have the Scan Gauge 2 and read 9999 mpg when coasting. It never occurred to be that injectors would be completely shut off under certain conditions but Mark's explanation makes sense.

As far as your tranny temp goes I tow a 12000# fifth-wheel here in the NW and even during the summer the temp rarely goes into the 190s.

Rob

 

We did take a trip tonight. It was 50 miles one way, mostly highway. The outside temp was mid 40's. My coolant temp ranged from 173-175. My tranny slowly climbed on the way to the ice arena until it hit 170.
On the way home, coolant temps were the same as on the way there but tranny temp hit 172.

The reason I am posting this info is an early post thought the 180's were a little low for the coolant. This was even lower. I guess I am hoping it's a bad sensor or scan gauge.

 

My coolant temp ranges from 170 to 185 or so. 190 if I'm having a bit of fun, and around 201 on a really hot summer day.