Transmission Issue

Hi everybody. Been a while. Here's my issue... I have a '98 Riv with 147,xxx miles on it. The transmission shifts flawlessly as long as I drive it gently, or as a gentleman or grandfather. If I have to accelerate rapidly like when merging onto a highway or rapidly passing that is when the problem starts.

Once I accelerate and get the RPMs up, afterward the trans shifts VERY harshly. Very hard. Banging every gear. Also, I notice a steady whine/growl afterwards as well. The problem will only clear up if I shut the car off for longer than a minute or two. Putting it in neutral or park will not stop the harsh shifting or growling.

It seems like the high RPMs raise the internal pressure in the trans and it takes a couple of minutes of off time to fully release the pressure????

Any thoughts?

Thanks.

Typically, a whining or growling type noise from a transmission means the trans fluid pump is going bad. Usually though, a bad trans pump doesn't shift harsh. You may have 2 separate issues going on where one problem "initializes" the other to happen.

Transmission questions are almost impossible to answer on a forum. A trans isn't something that one could simply take apart and look at for simple repairs/problems. Either way, you're probably going to end up at a trans shop.

Abaddon is right, very very difficult to diagnose these trans issues on a forum. With that said, my two educated guesses are either 1) the pressure control solenoid is sticking open giving you full fluid pressure all the time or 2) the fluid is low/dirty/something. Sometimes changing the fluid and filter makes all the strange issues magically disappear... IMO it's worth a try.

I agree with what Derek said regarding dropping the pan and changing the filter and the approximately 6 quarts of fluid and then see how it reacts.

Don't have it flushed by a shop. That caused me more trouble than it was worth. required a complete trans rebuild after the flush at about 80K miles.

You may need a complete teardown and rebuild but it would be worth just dropping the pan and replacing the filter and the fluid that is lost when doing that. Just to see. It's not that expensive if your doing it yourself or even at a shop that your comfortable with.

I made the mistake that believing a trans with only 78K or so miles would tolerate a complete flush.
Damn, was I wrong. If you've owned the car since new and had the trans flushed, say every 25 - 30k then maybe you can avoid a major problem.

But having it flushed with a machine for the first time at 70-80K is not a good recipe. Other than a recipe for failure.

Since the rebuild, and after installing a drain plug in the trans pan, I drop the fluid (about 6 or 7 qt's comes out) every 2 years based on my driving habits and am hoping that I'll not have to have it dissembled and rebuilt again while I have the vehicle.

Prior to the Trans Flush all was good. After it it started what I would call "Wheel Hopping" during hard acceleration while trying to get into traffic. While sitting at idle waiting for that spot where you can jump into the open spot, the drivetrain would jump uncontrollably and the wheels would actually hop under hard acceleration from a stop.

It was unnerving and felt destructive. Had to bring it to a reputable trans rebuilder and let them bend me over. They dropped the cradle and trans, then noticed my rear trans mount needed replacement (cost for part $600.00) also while trans and cradle was out of the way the brake lines needed replacing from master cylinder to front and back wheels. Used Nickle Copper lines for another $400.00.
Then when all was said and done and ready for pick up, paid the rental car company $600.00 and noticed the front fender was dented from the engine cradle they used and the rear quarter panel was scratched from repeatedly dragging the overhead air hose over the car.

That required a conversation that the owner did not want to have, but ultimately paid MY body man to fix it.

One month without the car and more money than I care to admit was spent.

I'm sure this is more than you or anybody else on the forum wanted to read but I had nothing else to do.

With all that being said, Rick, your car had the symptom(s) of a bad PWM Solenoid. Yes, a flush could make that "symptom" better or worse. Goo and grime get caught up in the screens of the solenoids. Adding the trans cleaner provided in a flush will either get rid of it, or gum it up even more.
I've used the flush machine on my Riv 3 times since I've owned. However, I don't put in the cleaner or the additive. I just use it to get all the fluid out.

Different example....I'm sure most of you didn't get to see my post about the Aztek acting up on me 2 weeks ago (because the post got muddied up and passed over). It has the same trans as the Riv (4t65e). I didn't opt for a flush, because the PO had a BG flush done 25k ago. I simply dropped the pan and changed the filter/fluid. Well, this made the problem worse. It actually put itself into full line pressure, and shifted like it had a mad shift kit for 2 days. Then it mysteriously fixed itself. My best guess is that the max line pressure blew out whatever was stuck in the solenoid/valve body. It isn't unheard of, either. I've fixed a few cars over the last few years by physically commanding max line pressure and driving around like that for a day. New trans fluid is one hell of a detergent....

Changing filter/fluid is realistically the only thing one can do for a trans. For ~$40, it's worth a shot.

Well I slapped the 96 computer back in as kind of a last resort before I have to start spending money. Shifting definitely improved, it didn't take it's time like it used to. Only time will tell if this fixed it or not. Still going to try and drop the pan and change the fluid/filter, see if that shows anything. Going to edit my write up for changing over to the 97 computer by adding a warning....

Abaddon wrote:

With all that being said, Rick, your car had the symptom(s) of a bad PWM Solenoid. Yes, a flush could make that "symptom" better or worse. Goo and grime get caught up in the screens of the solenoids. Adding the trans cleaner provided in a flush will either get rid of it, or gum it up even more.
I've used the flush machine on my Riv 3 times since I've owned. However, I don't put in the cleaner or the additive. I just use it to get all the fluid out.

Different example....I'm sure most of you didn't get to see my post about the Aztek acting up on me 2 weeks ago (because the post got muddied up and passed over). It has the same trans as the Riv (4t65e). I didn't opt for a flush, because the PO had a BG flush done 25k ago. I simply dropped the pan and changed the filter/fluid. Well, this made the problem worse. It actually put itself into full line pressure, and shifted like it had a mad shift kit for 2 days. Then it mysteriously fixed itself. My best guess is that the max line pressure blew out whatever was stuck in the solenoid/valve body. It isn't unheard of, either. I've fixed a few cars over the last few years by physically commanding max line pressure and driving around like that for a day. New trans fluid is one hell of a detergent....

Changing filter/fluid is realistically the only thing one can do for a trans. For ~$40, it's worth a shot.

I had driveability issues fixed on my Riv, recently, by reflashing the trans parameters in the powertrain module back to factory spec.

By the way, if you have not switched trans fluid to Dex VI yet, consider doing so.