Thats what I wanted to know. Using a ScanGauge2 or Torque we can monitor trans temp from OE sensor. I wasn't sure this was an accurate measurement.

 

That is the most accurate temperature.

 

At what temp do we start to get really worried. I just discovered that at slow speeds up a hill the trans can see 230 degrees. I also discovered that that's about where the cluster needle starts to go up...

 

The cluster needle will move at 230°F. That is the temperature that you need to pay attention. You can go up to 250°F, but don't stay there longer than a half hour.

If you need to cool the trans idle or fast idle in park or neutral. DO NOT shut the engine off when the trans is that hot.

 

Have you upgraded to a 6.0 transmission cooler yet? If you're towing, it's a good idea and usually < $100 for the cooler.

I was towing heavy this past trip, returning today, over mountains and such at up to 75mph, and never saw 180F on the transmission.

I am also running a John Woods valve body, which is supposed to help with slippage and heat. Cheap and easy DIY sway. Drop the pan, remove old valve body, install the new, keep it all clean, take lots of pics to make sure (I also am very careful to keep the same bolts back into the same locations).

You might also have some debris in your fins of the cooler, radiator, A/C condenser, etc.

I did replace the clutch fan from NAPA about 3 years ago on advice from folks here. Made a big difference.

 

Can ForScan also reset codes too?

 

Not yet. I had to drive from NY all the way to Wyoming to get the trans needle to move. I think the trans was good even going over the Bighorn mountains. It only got to ~230 at Yellowstone when towing up a steep grade at 25MPH where the air flow over the cooler is more limited.

I'm still thinking I have a fan clutch issue but haven't figured out how to test it properly yet.


I was fine on RT 80 between NJ and Nebraska. I never saw a trans temp that was concerning. I would often kick down from driving in OD at 70 to 3rd gear at 60 or 65 for some hills, but that been my standard operating mode for a long time now.



I'll have to look into that. My plan on the trans was to just do regular changes and use Mobil 1 trans oil.

This is something I should at least check. Is there some way to get a good view of the fins - like remove the front grill?

Tell me more. Was the fan not locking up? How did you determine it was a fan issue? I can't measure ECT directly but my fan doesn't seem to kick in until EOT hits about 228 degrees. Also it doesn't seem to "roar" unless I'm at about 2500 RPM or more.

 

The clutch fan on mine kicks into "roaring mode" about 217F

It's pretty easy to test and only costs about $50. Stop at NAPA, get new one, put it on. LOL.

But seriously, I read all different things about testing clutch fans. Do they feel solid, do they spin freely, etc.

In the end I had several pulled ones to choose from and couldn't tell any difference at all

When I called NAPA and they said $50 or something like that, I figured it was an easy choice. Overheating and bad clutch fan are big issues. I noticed a difference right away.

Rich (Tugly) saw high EOTs, like you mention, in my logged runs way back when and we started questioning the clutch fan.

We had the front end off to do the trans cooler, brush guard, etc, so pulled the fan and clutch while we were there.

I still have no idea how to properly test one, but the replacement was pretty easy to do with a fan removal tool. Wear gloves, those aluminum fins are hard on the knuckles

PS- not sure the best way to check the fins of the other coolers, but it's on my list to do Maybe some condenser cleaner like they use on commercial A/C units? Don't use high pressure, it can bend the fins.

 

It sure can.