Also, the autometer gauge will read the temps from the sending unit plugged into the drivers side of the tranny. AE and the shops scanner will read the temps from the stock Trans temp sensor just above the pan. I have noticed a difference in gauge temp from what the PCM sees as well. That's not uncommon. What i'm trying to do is understand what temps from what sensors you are seeing, so when Mark chimes in he will have an answere 4 U.

 

Your autometer tranny temp gauge says 220, their scanner says 210. What does AE say? Should be the same as their scanner.

 

Sorry, I didn't fix my typo. My Guage says 200 And their guage says 220 and so on. There is a 20 degree temp difference between the two, with theirs reading higher.

 

If AE reads the same as their scanner it sound like the heat is being generated when the TC is unlocked according to your description. Then when you get up to speed (somewhere around 35 mph) the Torque Converter locks fluid starts cooling. Doesn't sound like a cooler problem to me.

 

I've done it dozens of times, it's not as crazy as it sounds. I've seen other mechanics do it also....it's a pretty common method actually. Of course if you aren't comfortable then don't do it. Also, no reason to try the test if you are already feeling a nice draw of air from the fan....only want to try the test if you see the fan spinning but it isn't pulling any air that you can observe. If you guess right and the fan clutch is faulty then the engine will start and the fan will be held still. Then once you release the blade it will slowly start spinning again. If you guess wrong and the fan clutch is working, then your fingers will simply get thrown off the blade the moment the starter engages.

Here is a photo that shows how the test it done. This is how I diagnosed the weak fan clutch on my wife's truck. It never overheated but the A/C would get warm when stationary and then cooled off once she got moving again. Same symptom in my neighbor's Dodge truck but in his case the fan was nice and solid so my fingers were pushed off the fan immediately. We then checked the radiator for air flow and found it was about 70% blocked with oil vapors from his engine. (The 5.9 Cummins CCV dumps out at the front of the engine and ends up collecting on the radiator after a while.)

 

No problem, scanner is reading from the PCM and the gauge from the sending unit in the test port. Not a big deal - either way it's still high.

 

Any other ideas on what Else to check?

 

Sorry, I gotta run to work . If the bypass is new than you can rule that out. The bypass is in place to keep the tranny from being destroyed if the cooler lines become blocked and the fluid can't flow. I assume the tranny shop would do a flow check to see if it is a blocked or partially blocked cooler. If those all turn out good then it's time to drop the pan and see if there is any crap in there that would point to the problem . Do you hear any rattling (like bolts in a coffee can) when in park idling?

I'll check back tonight but I hope Mark K. See's this thread before then.

 

When I first fire it up in the morning (cold 40* or below) I can hear a rattle like bolts in a coffe can. Only for about 10 seconds, then I don't hear it again the rest of the day.

 

A few years ago Mine did that intermittently as well. Turned out being a broken sprag in the torque converter. Caused high tranny temps and a intermittent coffee can rattle. BTS was kinda surprised it happened but Brian took care of it just like he always does. Not saying this is your problem but the TC builds up some heat when not locked and I would be concerned that it would be the culprit if the cooler is fine and the fluid flow is good.

 

A 20°F degree difference between the test port and the internal sensor is normal. Sometimes the test port will be higher, sometimes the internal sensor will be higher. It depends on operating temperatures.

I know you said the flow is good, but what does that mean? At idle does it flow at least a quart in 15 seconds? That is the minimum acceptable flow. If it doesn't flow this much then there is a problem. If it does flow that much and is overheating then there is an internal problem.

 

Thanks Mark! I will call in the morning and check on my truck to make sure they did that.

 

Hey guys! I know it's been a while but I just wanted to close this thread out with some good news. It was the Trans cooler. I went to the junk yard and snagged a 26 row 6.0 cooler off the shelf for $35 and installed it. I wish I had done this a long time ago! Super simple to install and it doesn't get over 170 degrees! I hope his helps someone in he future! FTE and the brotherhood rocks!

 

Thanks for the followup, its always nice to know how the kinks get worked out eventually.

 

Can you see if they have another one or ten?

Seriously, I would like one for that price(and a little more for your trouble plus shipping) if you can find one.