To ALL of you that responded to my initial post on this subject, THANK YOU very much. First… regarding your comments, a MAJOR theme was that one simply should NOT tow using overdrive. I understand, and the person that mentioned driving at 3,200+ RPM’s for hundreds of miles (North GA to Tampa, FL) would NOT harm the engine did alleviate my fears of exactly that. If anyone disagrees, please speak up. I do change the oil/filter not more than every 3K miles and very recently changed the plugs and wires. Fortunately, the truck does NOT burn oil and its power seems good.
I’ve only owned the truck since 102K (been trailering for nearly 4 years) and the repair guy told me that the tranny definitely HAD been rebuilt in the past. I know the previous owner did a LOT of towing also. Finally, it DOES have the extra Tranny Fluid cooler but, when it died I noticed that the little radiator was not really even warm. I was told that there is a valve that closes the flow automatically (when pressure drops?), and that it likely DID close and further caused the tranny’s destruction. He told me that he removed that “valve” so flow will never be restricted again… does this sound correct?
I will detail the repair in the next paragraph, including advice from the repair guy. But first, regarding the trip back with the rebuilt tranny… I DID use overdrive on the trip back, since I’ve only just now read your admonitions not to do so. However, I did NOT use the cruise control since it tends to over-compensate for inclines and force 3rd gear. The major difference in the way I drove was that I would NOT try to power through inclines… I simply kept the accelerator in the same spot and let the MPH fall to wherever they may. If speed got to 50mph or less, I’d release the accelerator then press the OD OFF button to force 3rd gear which, I hope, made for an “easier” transition to the lower gear. Given the generally flat terrain on I-75, I did this not more than 10X over 350 miles. Before permitting OD from 3rd, again off the accelerator then press button for OD “on”, then ease back on the gas. Generally, the average speed was 60mph with a CONSTANT 2,000 RPM’s, giving me just over 11mpg… for which I was grateful since previous trips at that speed yielded around 9.5mpg. So… would you say that this strategy is or isn’t acceptable, given that I was NOT switching back and forth between 3rd and OD?
Repair guy pitied me… was going to charge $1,550, but quoted $1,350 and agreed to it as long as I paid in CASH (no check, debit or credit cards). He said there was MUCH ground metal on the bottom, and that the rear of the unit was so bad that he couldn’t really even determine what, exactly, went wrong first. The fluid was full, but he said he was surprised that I could even limp 1/2 mile to the next exit by sitting in Park for 10 minutes, then getting about 35 seconds of “gear time” before it let go again. He added a bottle of “Lucas” stuff to further protect the new tranny when he saw the 7,000lb trailer I was towing. Like all of you folks, he told me that the back and forth between 3rd gear and OD was the “kiss of death”. He did, however, seem to feel that if I could “manage” overdrive by not permitting the downshifting (ie, keep power constant and just let the mph drop on the inclines), then that should be OK for the tranny. As noted, that is exactly what I did. Also- you may recall that I mentioned a slight drop of about 300 RPM’s that occurs in Overdrive after about 5 seconds… he explained that was the engagement of something called a “torque converter”, which is normal.
While I apologize for the length, please know that I’ve provided these additional details because YOU ALL are the smart ones!! I was so thankful for your original responses, and have given this further information for your comment regarding use of overdrive while pulling a trailer. Given the 11mpg on the way back (which is VERY good), would you consider the “adjustments” I’ve made in driving style to be acceptable for future tranny well-being? Or is driving 500 miles in third gear at 3,300rpms, probably below 9mpg and about 55mph (on 70mph interstate) just absolutely necessary? I truly value and respect your opinions… thanks.
PS I used to own a GMC Sierra 2500 Diesel with Allison tranny, so I KNOW how much better diesels pull. That truck was about $37,000 in 2003… and after Katrina, the price of diesel combined with the payments was KILLING me!! Next time, I’ll only get MANUAL transmission if gas…