View Full Version : 98 GM 6.5Liter Turbo Diesel

09-07-2004, 11:31 PM
i have a 98 gmc 2500 with the 6.5 liter trubo diesel and having a slight worry about the tranney. it seems when the truck is cold the tranney won't grab untill a higher rpm like it won't grab. tranney fluid is full and was wondering if anyone has or had this problem and the truck has about 99,000 miles

09-08-2004, 12:39 AM
My guess is that you have the 4L80E tranny. We went through one of those every 80,000 miles on a 3500HD. Of course it always pulled a 20' enclosed trailer. The new Allison is a great improvement.

We did find some stuff that you poured in that helped what you are talking about. I will find the name of it and let you know tomorrow.

09-08-2004, 11:31 AM
You can beef up a 4L80E so it will out perform just about anything. First and foremost, do you have a sizable external cooler at the front of the radiator? That is a must for longevity. It sounds like the pump is starting to go, and if that is going, the torque convertor will be going soon after.
Ad a shift improving kit and test the electrics when you rebuild and you should be good to go....Oh yeah, plan on a $2,000.00 bill you go to pick it up.

None of the electric shift trannies are cheap like the old vacuum shifts were to redo. In comparison, we can pull a TH400 tranny, have it up on the bench, stick $350.00 worth of parts in it, and after an 8 hour day have it back in the truck and running. A 4L80E will take the same time to remove, but the parts for rebuild are going to hit you at $1,500.00.00. For something that was supposed to make life easier and save time, the computer is a miserable failure in this instance.

Good luck with your tranny.

09-08-2004, 11:52 AM
I agree with uniscaper, the cooler and shift improver will help out a lot. Theres a place in my home town that rebuilds race transmissions and I believe he does the newer trans, he would want about 2900 but I doubt that trans would ever give a problem again, the shop is called rossler, he's a pretty famous trans person because he builds them good. Or if you want a cheaper route look on ebay, my friend bought a 4l80e on there for 900 bucks and has had it in his race car for 2 years now with no problem, thats where i'll be buying a e4od for my ford.