2004 bonneville transmission problems

[hardheaded]

Need some help with this please. 2004 bonneville 3.8 engine. Sometimes when taking off from a stop the transmission acts like it is not in drive. Bangs into gear when you give it the gas. And sometimes when very hot out it goes into high pressure mode.
The banging into gear doesn't happen very often, maybe every couple of months. 148,000 on the clock.
Do you think this could be a pressure solenoid problem or our we looking at a rebuild ? My sons car and doesn't get driven alot.
Been like this for 4 or 5 years now. Thanks !

 

[Furious]

Check the transmission fluid level.

Any codes?

 

[GON]

Install a shift kit and update the fluid to DEX 6. Solved a like issue for many years on a 2001 Bonneville SSEi.

 

[Furious]

Install a shift kit and update the fluid to DEX 6. Solved a like issue for many years on a 2001 Bonneville SSEi.

That is a possibility but there is various things that can cause harsh shifting, erratic shifting, etc

Low fluid level, many GM vehicles are picky with dirty/faulty MAF sensors which effects line pressure, solenoid issues, etc.

Rule the simple things out first.

 

[71Chevyguy]

I had these problems in my LeSabre when I bought it. Put a shift kit in it and have not had a single issue with the transmission since. That was almost 10 years and 100k ago. I highly recommend installing the shift kit regardless. Mine was barely drivable before I put it in.

 

[Astro14]

After 4 YEARS of driving with this problem - the transmission may be too beat up to be fixed.

But start with the simple - clean fluid at the correct level. Then see where you are. Then a shift kit. Then see where you are.

Then, if it’s still happening, start shopping for a replacement…

 

[Lubener]

I would hope the fluid and filter have been changed since this issue began. That's where I would start. It may be too far gone by now.

 

[redhat]

This should help. Read the posts by @ls1mike

R

Thread '2004 LeSabre/4T65 GM hard shift when hot'

Jan 12, 2020

Dad has a 2004 LeSabre, your typical 4T 65E and a Series II 3.8. Beautiful car runs great and shifts great about 120 K on the clock. After you've been driving the car for a while, out of nowhere the car will start to shift very hard almost as if it is commanding full line pressure. When this happens in the shifts will actually make the tires chirp sometimes. If you throw the car in neutral turn the key off and restart the engine it'll drive and shift fine for another half hour or hour.

I think I've vaguely remember seeing about this and the fix was some sort of Mr. shift kit or maybe a...

• redhat
• Replies: 17
• Forum: Mechanical/Maintenance Forum

• 

 

[ls1mike]

148,800. It might be time for a rebuild since it has been acting up for awhile.
Try the fluid change, shift kit and filter. You have nothing to lose.

 

[hardheaded]

I forgot to mention i changed the fluid and filter with Dex 6 and added Lube Guard Red with no help.
Doesn't do it much, but would like to save the trans. Maybe the shift kit is the next move. Thanks !

 

[hardheaded]

Could you please tell me what shift kit was used to fix this .?

 

[ls1mike]

Could you please tell me what shift kit was used to fix this .?

Transgo 4t65e shift kit

 

[hardheaded]

Thanks.

 

[hardheaded]

I wonder if this would take care of the banging starting off from a dead stop ?

 

[clinebarger]

I wonder if this would take care of the banging starting off from a dead stop ?

This could be from wear to the forward input clutch piston causing a leak in the apply circuit, New Piston & Longer lip....Lip Seals will cure the issue. Not part of the SK shift kit but touches on the issue in the instructions.

 

[Gasbuggy]

I remember this problem with my 08 Impala, only had 70,000 miles. The banging is a low line pressure issue. Changing fluid didn't make a difference. As I recall, even just bumping up pressure 10% in the trans tune would eliminate the issue entirely. The shift kit is probably the way to go.

 

[wlk]

Valvoline Maxlife and Lubegard Red, give it a few 1k miles to clean and maybe help the shift. Not your problem but similar, my GMs had harsh 1st to 2nd shift and the combo eliminated it in a thousand miles or so.