I've been lurking in these forums for quite a while now - love them!!! I'm sorry if this turns into a long post...!

I really need some advice about some possible tranny problems in my '98 SLE. I'm getting about 20MPG on the highway - I drive about 40 miles each way to work (mostly highway). I generally drive between 75 - 85 MPH (quite slowly compared to the other vehicles on the road!). 85 MPH is around 3200RPM.

I took the "Bonnie" into the shop today because I was concerned about the low MPG (it may be related to my lead foot) and a slight whine when the car is in overdrive. The whine goes away when I shift into 3rd gear.

The car had its transmission fluid changed around a year ago. It had a complete flush and change a couple of months ago because of some debris in the pan during a service check.

Anyway, when I picked up the car this evening, the mechanic told me that it seemed to have a problem shifting into 4th gear (that'* the overdrive gear - right?). He had consulted with a transmission shop he works with and they said that that something may be stripped (sorry can't remember what) inside the transmission and that "thing" may need to be rebuilt. It could cost (worst case scenario) around $1600 + tax.

I remember the car having problems with overdrive not kicking in on the highway back in 2000. I found the service report - The dealer'* tech reported "Found update for transmission. Reprogrammed PCM as needed". I vaguely remember him saying something about using SSE programming.

On the way home from work, I found that the car shifts into 4th around 5100 RPM if I give the accelerator a hard push when going 65-75MPH- is that normal?

Does anyone have any insight as to:

1. Is there a problem????
2. What the problem may be?
3. What the tech may have done during reprogramming?

Thanks in advance for any help.

The problem is, You let them flush your transmission. I've heard this story many, many times. Get a flush and a few months/few thousand miles later the trans fails. All you get out of a trans flush is an STD (someone elses transmision debris"

Thanks for your reply.

Actually, I forgot to mention that the whine was there before the first transmission fluid change and went away immediately afterwards. It seems to be coming back again. Any more ideas?

Jr's3800,

Thanks for your reply. I've just remembered what my mechanic was told by the transmission shop - exactly what you said... "slowly stripping off the 4th gear splines in the transmission". So, it'* probably the expensive repair scenario! Does around $1600 sound about right?

Thanks very much for all your help. I'm going to take it in on Monday morning. What kind of warranty should I expect? Once they fix the problem, is it likely to happen again?

Speaking of the 4T65-E trannies....

My 99 has given me absolutely no problems and I even do some light towing with it (no more than 300 lbs.). At 85K it'* still purring just fine, but we don't drive it hard at all. However, ever since day one when we bought it with less than 30K, it has always "hunted" into the next gear. It'* a very small "hunt", but noticable. You can literally see the tach jump up about 200 RPMs before it drops into the next gear. It does it primarily during light to moderate acceleration. We took it back to the dealer before 36K and they said they updated the PCM and it should take care of it...but it never did. Is this common?

I take it that it'* nothing to be too concerned with?

Well, I took it into the transmission shop on Monday. The mechanic there confirmed that the 4th gear splines were stripping off and he'* seen a lot of 4T65-E'* over the years. He attributed it to a design fault. Anyway, it was going to cost approx. $1800 to rebuild (including tax + car rental).

I feel bad saying this, but I traded in "Bonnie" that evening for a 2004 Hyundai Sonata. Nice car - not nearly as powerful or sporty as my '98 SLE, but the "Shiftronic'" feature is great!

I need to vent now...

I bought my Bonneville in 1998. It'* upper intake failed in 2002 - an expensive repair that GM should have covered - they should issue a recall for their bad design. Had to replace the fuel pressure regulator a couple of months ago (luckily there'* a recall on that). The transmission failing was the last straw! It only had 83800 (mostly highway) miles on it. It was well looked after.

I'll miss my Bonneville. This was my 2nd Pontiac (the first being a '78 FireBird Esprit - died around 85000 miles). I think I'll avoid GM cars in the future.

Wishing everyone in this forum "all the best!".