Allison is getting HOT! What to do?
I have a 2001 Duramax/Allison with 187,000 miles. It is completely stock with no power chips or other modifications. The use has been approximately 25% towing with most loads being 10 to 12,000 pounds and a couple of occasions of more than 30,000.
The transmission has never given any indications of slipping or noises, but it recently started getting hot. I have changed both the internal and external filters and fluid a couple of times. Now it tends to get hot after about an hour of highway driving even without a load. When the warning light goes on it goes into a mode like tow-haul where the engine braking and higher shift speeds take effect. I verified that it is getting hot with an external thermometer that showed a 215 degree reading on the case just in front of the pan. That was after it had already cooled down for 20 minutes or so. Meanwhile the engine oil pan temperature was only 138 degrees and the ambient temperature was about 50 degrees.
The "Dead Allison" thread from December looks kind of similar in the comment that a converter failure can cause the overheating. In talking with a local transmission mechanic he recommends both replacing the converter as well as going through the transmission.
I would like to avoid working on the inside of the transmission if possible due to a lot of expense. Besides, from the comments on this forum, it sounds like the Allison is pretty bullet proof up to 300,000 or so miles. Can I get by with only replacing the converter?
What should I do next? We are going to check the codes first to see if it is giving indications of internal failure, but other than that I am clueless. Thanks for the help.
T.C.--2001 Crew Cab, 4x4, LS, Short box, Duramax/Allison, Sunset Orange<BR>e-mail--t_c_mallett@hotmail.com