When I tow at hwy speed (75) approx 3300 rpm(4.3 gears) my trans gauge begins to rise almost to yellow. If I back off to 70 mph 3000 rpm the trans stays cool. Is this normal? How high should I go? I like to stay with traffic. I turn off overdrive so I am in 3rd. gear. My TT weights around 8000 lbs loaded. I have the V10 4.30 gears.

 

Do you ALWAYS tow without the OD on? With the OD on you can be assured that the torque converter is locked and the transmission is operating at it's coolest. Why don't you try towing in OD. Don't let anyone here tell you it is not safe!

I would change the fluid and ensure there aren't any kinks or anything in the lines to the cooler. Maybe at higher speeds and pressures the fluid cannot get to the cooler fast enough.

 

Also make sure your cooler isnt full of dad bugs and leaves or anything like that. Check behind it also, stuff can build up in some weird places.

 

What do you mean? Last time I checked tranys run cooler when they are in 3rd gear insted of 4th. Not to mention 3rd is easier on them.

 

Do you have an aftermarket tranny cooler?

 

I never tow with the overdrive off. I usually switch the cruise off and back off a few mph when I come to a hill that I know will cause a downshift. My trans always runs cooler in overdrive. I tow a 10k trailer

2000 Ex 7.3L 3.73LS

 

I will try leaving in OD. The first time I towed the trans would shift down from over drive after several miles gain some speed and shift back up. That is why I started turning OD off, no shifting at all.My fluid was recently changed by dealer. No aftermarket cooler.

 

My first suggestion is back off the speed some...your TT tires are rated at 65MPH (ST tires)...75MPH is smoking for sure...I know others do it but...you will also notice a pretty significant improvement in MPG's at 65 vs 75

I assume at the RPM's you reference you are certainly running a V10 like me.

I also assume you are talking about the FACTORY trans gauge?

Here's my experiences with a 7500# TT (our old TT) and 7000 miles towing last year thru Black Hills, Big Horns and Rockies (some challenging climbs). With my previous 3.73's and the load/altitudes I had to REALLY work the motor at some serious RPMs (5000) in first if I lost momentum on a grade just to be able to pull the hill in second. While pulling the hill I ran usually 3500-4000 RPMs in second. Trans temp gauge never budged. I did this in JULY with front and rear A/C's going. I AM running synthetic trans fluid I had Ford put in.

The trans gauge we have is really a fancy idiot light...it will NOT move until temps hit 220...pretty HIGH by tranny temps...as soon it starts to move, you should be pulling over IMO...something is not right with your setup...to get to the yellow you need 250 degrees...cooking territory...

Check out this site http://www.intellidog.com/dieselmann/b_smoke13.htm for details...this guy did a nice job of calibrating the idiot light...

Last question...when I was pulling these steep grades...there is a LOUD aux cooling fan that kicks in and out...at first I thought it was the engine RPMs but it comes in and out...a SERIOUS fan for sure...do you hear that come on?...perhaps your thermostat for that aux fan is bad or perhaps the fan is bad?...

If the mechanicals check out...I think I would try backing off the speed and see how she tows...Yellow zone is BAD...250 degrees is serious temp and your have seriously ended the life of your trans fluid...a fluid change is needed at 250 SOON...

Good luck and hope the link helps out

 

Thank you for the link (X_Hemi_Guy) it was helpful. According to the gauges listed I was at the 230 mark. It was real quick, as soon as it moved up I backed down and the needle moved to normal. I am still going to have fluid changed and a system check. I dont know what caused it, on the way out of town the gauge never moved but on way back it did that once.

 

No aux fan on the V10 or otherwise. What you are hearing is the fan clutch engaging. Completely normal.

The fan clutch operation is regulated by a valve that is opened and closed by a thermostatic spring. The valve controls the flow of a viscous silicone fluid between chambers in the clutch assembly. When the engine is cold, the clutch is essentially disengaged, which is why the fan runs at its slowest compared to the engine's speed. As the engine warms up, the air flowing to the fan assembly becomes hotter. The hotter air causes the thermostatic spring to unwind and open the valve. Silicone fluid from the reservoir chamber flows into the main chamber, engaging the clutch, and the fan spins faster (though it's still slightly slower than the engine).

Quoted from another site because I didn't feel like typing it.

 

You have a lot more checking to do youngin. Or maybe checking with the correct sources.

 

Quote:

Originally Posted by Monsta

You have a lot more checking to do youngin. Or maybe checking with the correct sources.

Well not only have two good mechanics tell me this, the manual for my Jeep says to disengage over drive when towing, and the local transmission shop told me to disengage it when towing. So set me straight then. Does running in 3rd gear cause MORE wear and tare / heat on the trany then 4th? I believe it causes more engine wear but I always thought it reduces the heat of the trans fluid because there is not as much force between the gears because they spin faster in 3rd so the trany does not have to pull as hard.

 

Your last sentance kinda confuses me.

Let's just say this. In OD your torque converter is locked. A locked TC equals cooler transmission temps because the TC's pump and turbine aren't swapping fluid around. It is the TC's operation that heats up the fluid and not necessarily the absorbing of heat from friction of the gears meshing...FWIW.

This is not the case is direct (3rd) in most cases. The TC remains unlocked especially at those speeds and loads he is talking about. Although the TC can lock and unlock in 3rd & OD depending on road & engine speed, it is much more prevelant in 3rd than in OD. In OD, the TC unlocks for a split second it seems until it downshift. You can actually FEEL the lockup while in 3rd before it shifts to OD. It almost makes the truck feel like it has 5 speeds.

That is why it is best to tow whenever possible in OD. If the tranny isn't hunting between gears (for the umpteenth time) then leave it alone.

A good source for some simple mechanical explainations is www.howstuffworks.com.

 

Monsta,

Thanks...Pulling Powder River and Togowotee passes last summer you could definitely hear the fan come on and fade down...at first I thought it was just the high RPM's of the V10 singing music to me...but after pulling the pass at a constant RPM's hearing the loud ROAR fade...I figured it was a/the fan...don't ever really hear the fan running in "normal" driving so I thought it was an additional one...guess it never really kicks up to that level unless you are pulling 9600' plus passes in July heat! LOL

Thanks again.

 

I do not have aftermarket cooler. It thought it had one but I guess it shares radiator. There is a small cooler by ratiator but it looks like it goes to power steering. I never saw a cooler for a power steering before.