Cruise control induced downshifts

[davjamison]

I'm a little paranoid about repeated downshifts causing early transmission failure, plus it's just plain annoying. My X is a 2000 with the SOHC V-6 and 5 speed auto, with typical use having the cruise set at 79 and towing a small utility trailer. In areas with even very small hills, it constantly makes what feels like a downshift, but I think it is just the torque converter unlocking, as it only jumps about 300 RPM. If that's not enough, it then makes a genuine downshift (same as if I pressed the button turning overdrive off). If the first "downshift" is just the converter unlocking, am I right to assume that it is relatively harmless to do it fairly often, and I should only be concerned about repetitive genuine downshifts? I'm tired of not using the cruise control in hilly areas. I have tried just running with overdrive off, but there is enough engine noise at 75 - 85 to make me think twice about that as well. Input or suggestions?

 

[Jefe]

Well, that IS what the overdrive on/off button is for. I've made it a habit to flip overdrive off before i'm about to climb a hill (especially when I'm towing), becaue i know its going to do it itself anyway. And as soon as i top the hill i flip it back on.

 

[Robert]

In all likelyhood the noise you are hearing is the torque converter unlocking. A couple words of caution though. Your overdrive should not be used for towing regardless of how light your trailer is. Since you mentioned that it is frequently unlocking your torque converter then you should not be in overdrive. Whenever your torque converter unlocks, it generates heat. The transmissions on the V6 Explorers are notoriously weak. Excess heat can lead to pre-mature failure. I hope as a minimum you have a transmission cooler and towing package. If the noise is too loud when driving 75-80 while towing your trailer the best thing you can do is slow down. Here in AZ the speedlimit is 75 MPH on the highways and yes I have towed my cargo trailer at 70 MPH. I even hit 75 and maybe 80 MPH a couple of times while towing it and now looking back on it I realize how dangerous it was. My trailer pulled excellently from Ohio to AZ although I did run my the first 1 1/2 days with the OD on. My Check Engine light came on across Missouri once I got into the hills. Like yours, my torque converter was constantly unlocking and locking on even the slightest grades. I drove the rest of the way with the OD off and actually picked up a couple of MPG.

 

[jimmiecakes]

I'll second Roberts comments. I believe that your owners manual may have a few words about overdrive/hills/towing. The overdrive clutch pack is generally pretty small and it doesn't take much to add some real stress on the fibre plates.

As a volunteer fire fighter/rescue technician, I can vouch for Roberts views on towing at high speeds. I scrape a lot of folks off the road after they found out that they need to add the word "yet" to the inevitable "....and it hasn't hurt me" statement.

 

[Alec]

When I towed trailers when my truck was stock I always turned off the OD. Basically for the reasons mentioned above. Even if you are at higher RPMs, your engine and tranny could be more efficient in 3rd gear for that load. Now with the s/c I can leave it in OD cause it doesn't have to downshift much, it just makes more boost. But definately, in a stock application, turn OD off.