480le trans trouble

Levi · December 27, 2006

I work for a small construction company and we have a 1993 GMC 3500 dually with a tool bed. It has a 6.5l diesel engine and a 480le transmission.

We have had this tranny rebuilt twice in the last two years. Just yesterday it stopped working again. Without warning it started to slip then a burnt fluid smell, then nothing. As of right now it will do absolutely nothing when put into any gear and you can smell the burnt fluid when you walk up to the truck.

The truck is always heavily loaded with all the tools needed for a bulkheading crew. Is this the reason the transmission keeps failing? If so is there a way to make this tranny bullet-proof or another transmission (auto or manual) that can be installed to take the load?

It does have a trans cooler and it doesn't seem to have any leaks.(some seepage)

The burnt smell is the worst I've smelled. Could low fluid have caused the trans to fail completely with no other symptoms? (slow shifts etc.) I asked the forman if the trans fluid level was right and he told me it was. This morning when i checked it it was WAY overfull, about 2 inches up the stick. I suspect he may have just added fluid and told me it was ok since it is his responsibility to check the fluids in the truck daily.

thanks,

Jon

slowpokebanshee · December 28, 2006

twice in two years may or may not be excessive, how many miles? also who rebuilt it? maybe check into a GM reman, depending on model you can get 3-36 warranty, or at the least a 12-12 warranty. check around, believe it or not....the dealer may be cheaper parts and labor.....also some independent shops just don't have the "experience" needed to overhaul transmissions in house, I work at a GM dealer and several independent shops (including independent transmission shops) sublet their transmissions to us for overhaul. they do the R&R part, and bring us the transmission for repair, we charge them same as we would to John Q. Public, and they mark it up substantially. but because they do the R&rR often times there is no implied warranty. not trying to bash independent shops, because I am aware that there are as many crooked dealers as there are shady independent shops, just saying call around and see who has what for how much, and what kind of warranty....good luck

ChevyTech007 · December 28, 2006

If it has been rebuilt twice, do not have it rebuilt again. High mileage? A rebuild usually just means new clutches and some seals. It does not mean replacing everything. If the fluid level does not drop when you start the engine it means the pump is not pumping which would cause it to burn up. If you plan on keeping the truck I would have it replaced at the dealer with a GM trans. They have a great warranty that is actually backed up and are not really any more expensive that an off breed trans.

Levi · December 29, 2006

Thanks guys. The trans rebuilder we use is supposedly very experienced 10-15 years, master ASE certs in transmissions etc. He seems on the up and up. He told me yesterday that he wasn't sure if that transmission would ever stand up to the weight of the truck and contents. I would hate to go and get one from gm with the possiblility of it not being up to the task.

The second time it failed there was a small bolt inside that had a passage drilled through it that broke and allowed something to turn that wasn't supposed to. This time the front pump or torque converter has gone out possibly damaging hard parts. It seems to me these might not have anything to do with the weight of the truck. If not for these (maybe) freak problems the transmission would handle the heavy truck fine.

My boss wants me to check on converting everything over to a nv4500 manual but I'm having trouble finding all the parts. Flywheel for a 6.5l, clutch pedal and hydraulics for a '93 3500 etc.

I'll call the dealer about it. If it's not to expensive that may be the way I go. Thanks again for the help guys

, Jon

mmmikkke · December 29, 2006

Could be that your trans cooler is not working right. Does this truck have a trans temp gage? If not, you should put one in. How much does this truck weigh, anyway?