suggestions for haul

[farmerpatrick]

Well, I am finally making my big move back home from Camp Lejeune, NC to Holt, FL. I bought 10 acres of a pecan orchard and in the process of having a repossessed (cheap) mobile home moved over there. Anyways, Almost 800 miles. I'll be towing a trailer approx. 4500 lbs of household goods. Last weekend I towed one load of junk home but it was much lighter. Didn't have any problems and I kept it in Drive at about 65 mph on the interstate. I have added an auxiliary tranny cooler (700r4 btw). I got 15-17 mpg on that trip. Towing a 6x12 u-haul trailer. I know this isn't an incredible load or anything, but I'm a little worried about the old Blazer. I 've just changed the oil and filter, checked the brakes, changed the fuel filter, changed the rear shocks. Any good suggestions? If I take I-95 to I-10 it's completely flat but kind of boring, whereas I can also go through Atlanta, but I hit some hills going that way.
I would like advice, I'm not used to towing much over 10 or 15 miles to the boat ramp. Do I need to keep it in Drive rather that OD?

[BC Clark]

I believe the owner's manual says always tow in drive. The real issue with the 700R-4 is heat not strength. It's going to pop out of OD with anything serious. The problem is, and others on this forum I see have noticed this, that in OD with only light throttle the torque converter will unlock. In OD the transmission does not flow enough oil to dump the heat generated by an unlocked torque converter, especially while towing (even with an extra cooler). Sounds like you are going to be towing over pretty flat terrain, so you might get away with leaving it in OD. However, unless you really know the feel of your truck and can tell when the torque converter's unlocked, I would recommend two things. 1, a tach, if the rpm jumps with throttle faster than your truck speeds up - you're unlocked; and 2, a tranny oil temp gauge. When I put my cooler on I also added the Perma-cool remote filter and temp gauge (one of the better 79 bucks I've spent), now I can read transmission oil EXIT temperature. With the oil filter and temp sender before the radiator cooler and the external cooler located after the radiator cooler, I notice that normal exit temp is about engine temp or less. With the TC unlocked, off it goes! In drive the TC will remain locked longer (locks in 3rd and 4th) and if it does unlock the higher RPM will allow the pump to flow more oil through the coolers.

[BC Clark]

I believe the owner's manual says always tow in drive. The real issue with the 700R-4 is heat not strength. It's going to pop out of OD with anything serious. The problem is, and others on this forum I see have noticed this, that in OD with only light throttle the torque converter will unlock. In OD the transmission does not flow enough oil to dump the heat generated by an unlocked torque converter, especially while towing (even with an extra cooler). Sounds like you are going to be towing over pretty flat terrain, so you might get away with leaving it in OD. However, unless you really know the feel of your truck and can tell when the torque converter's unlocked, I would recommend two things. 1, a tach, if the rpm jumps with throttle faster than your truck speeds up - you're unlocked; and 2, a tranny oil temp gauge. When I put my cooler on I also added the Perma-cool remote filter and temp gauge (one of the better 79 bucks I've spent), now I can read transmission oil EXIT temperature. With the oil filter and temp sender before the radiator cooler and the external cooler located after the radiator cooler, I notice that normal exit temp is about engine temp or less. With the TC unlocked, off it goes! In drive the TC will remain locked longer (locks in 3rd and 4th) and if it does unlock the higher RPM will allow the pump to flow more oil through the coolers.