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9 speed Transmisson Towing Temperatures

12K views 10 replies 7 participants last post by  Rick Anderson 
#1 ·
I replaced my 2002 Liberty with a 2014 Cherokee TH as I needed a good vehicle to tow my 3500# boat and to date the Cherokee has not disappointed - in fact I think it does a better job than the Liberty.

I however, have some questions on transmission operating temperatures. I have towed my boat from one end of Ontario to the other along highway 401 and general operating temperatures are in the 74/77 C (165/170 F) range with occasional spike to 80 C (176 F) when running up long or steep grades. These ranges seem normal to me. I recently got caught in a major traffic jam to due road construction with constant stop & go and the transmission quickly spiked to 90 C (194 F) causing me a lot of concern. I exited the traffic jam at the first opportunity, but not before transmission temperature reached 100 C (212 F). Once I got moving again it gradually returned to a normal operating temperature range.

Did I over react to the temperature spike to 100 C (212 F)? If so at what maximum temperature should I be concerned? Is there any operating procedure that can be done to help reduce climbing temperatures?

Any and all thoughts/advice will be much appreciated as I do not want to do anything to damage the tranny on this great vehicle.
 
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#2 ·
Not familiar with this transmission, but as a reference, the factory service manual says that if my transmission temperature in my truck reaches 260F, it will disable overdrive and lockup. It re-enables at 230F. So those temperatures don't sound like cause for concern to me.

And my truck towed a 22' sailboat cross-country, and towed my car 220 miles, and now has 208K miles on the original driveline, no issues.
 
#5 ·
270 degrees is a common limit and 300 is time to back off and cool it down. Your temperatures are normal and no cause for concern. Any transmission which uses a radiator cooler can see coolant tamps up to 240-245 degrees and the fluid will not be cooler than that coming back from the cooler. On my diesel trucks I start downshifting and backing off the go pedal at 230.
 
#6 ·
#9 ·
You can add fluid to the 62 TE. Just remove the cap on the dipstick tube. Which is also where you put in the dipstick to check fluid level.
 
#10 ·
Most transmission fluids will NOT suffer any oxidation or breakdown if the temp stays below 180°F.

If it goes above that, it will stress the fluid and start breaking it down, but only slowly. How much and how fast depends on the fluid. Synthetics do withstand heat much more than conventional, but the additives package has to resist the heat as well. Most of the newer and higher quality trans fluids will resists those higher heats. Dexron II would NOT.

The fluid only rarely going over 180°F but staying under 225°F, IMO you're still in the safe range, especially newer fluids.

If you go above the 225°F for more than a few moments, I'd do something to intervene and cool it off some, take it out of overdrive, etc. I'd probably wait until I saw 250°F before pulling over and shutting down. Especially a small trans, not a lot of fluid in there, so its temps can spike much quicker than something like a big truck Allison trans. From your description, you were over cautious, I'm sure your trans is fine.

If you spend more than a few moments above 250°F OR a lot of time above 225°F, I'd think about changing trans fluid more often, at least on the severe duty schedule in the O.M. I think its a reasonable argument, even though the fluid can take these temps, in these conditions it is more severe than normal driving and breaking down the fluid a little faster.

275°F in a small trans, would scare me personally, probably wouldn't cause damage, but like I said, in a small trans, it might, I'd be scared of quick spike taking it even higher.

Fluid Temp goes above 300°F, in most trans, that is hot enough to possibly damage internal parts in the trans, often hardening or ruining seals, that create internal leaks and poor performance. In some cases, where metal parts are already very hot, the lack of cooling of the hotter fluid might allow the metal to get even hotter to the point to damage metal parts. Or damage friction materials that temp goes up corresponding high because of the much higher fluid temp. Keep in mind I said, most trans, some can take a lot more heat than others.
 
#11 ·
You can add fluid to the 62 TE. Just remove the cap on the dipstick tube. Which is also where you put in the dipstick to check fluid level.
From what little I read about the two new ZF transmissions, they are like the Mercedes NAG1 trans; the fluid level needs to be very precisely set. That is why the do NOT include a dipstick and cap the fill tube with a "Dealer Service Item Only" cap.

At least on the NAG1, the cap is removable (you do have to twist pretty hard, lube the seal before putting it back), and you can get the special tool dipstick off of ebay for a reasonable cost. The chart for level vs temp is in the FSM, but also floating around all over the internet (the chart NOT the FSM) that a google search can find. The key is to read the trans fluid temp, which is done by the Dealer WiTech Tool that accesses the temp sensor in the trans. Personally, I had installed a trans temp gauge in my Jeep, so I don't need that step to read fluid temp. I also have the AutoEnginuity software that turns my laptop into a scan tool that can read the trans temp gauge, if needed. More than once I siphoned fluid out of the trans, cause my guess to get the level right was too much.

I.e. A DIY'er can service the NAG1 trans, if they are good/dedicated enough to the precision to do it properly. Most cars owners are NOT, and that is why they cap the fill tube and tell you to go to the Dealer.

I'm sure the use of the wrong fluid in trans in the past was another factory in the decision to cap the fill tube.

Don't know about the new ZF trans, but lets keep our fingers crossed its the same as NAG1 at least.
 
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