: Do I Have a Bad Transmission?

10-05-10, 11:28 AM
Good morning everyone,
These last few days I've noticed that my car seems to be rough between the 1-3 gears. The RPM for all these gears usually stays at 2k with no fluctuation, meaning when a new gear kicks in, the RPM doesn't lower and then doesn't rise until the next one. Another thing I've noticed is that when I am coming to a stop, at around 3-5 MPH, there is a thump that sounds like its coming from the trunk, a few times it has felt as if the scar sort of skidded a bit. What do you guys think this can be?

10-05-10, 12:30 PM
Sounds like maybe a mixed bag of problems. The early STS's did have some rear end problems (maybe the thump from the trunk area); could also maybe be a clutch lockup not releasing when slowing. Just a couple of guesses; good luck with your diagnosis (but it may be time to bring it in).

10-05-10, 12:39 PM
Thank you. As you may already know, the car is certainly out of warranty. What do you recommend is the least expensive and easiest route to take first?

10-06-10, 05:53 AM
You have to isolate the noise, determine the location and go from there. There was a seal recall on the differential; you need to see if that was ever performed. Being a driveline noise it can be a lot of things, so any advice I give, is just a WAG (wild ass guess). I still think you need to take it in (and then decide what they can do for you and how much it is going to cost). Maybe then you can prioritze your repairs and evaluate what truly needs to be fixed. (It's a Caddy, so nothing is likely to be cheap, but maybe it won't be too bad.)

10-06-10, 11:30 AM
C&C, thank you for that. How do I determine if the seal job was performed? I've read that Cadillac's have 5 year/100k mile warranty on the drivetrain, do you think I am still covered under that or is it too late now?

I am not exactly sure when the in-service date for the car was, but assuming GM only counts years, I am certainly under the 5 year/100k mile limit. How can I find that out also?

10-06-10, 12:11 PM
This one?


10-06-10, 02:08 PM
Bring that 'puppy' into an authorized Cadillac dealership and they should have records of whether the pinion seal replacement was performed. While you're at it, just ask them about the drivetrain warranty and have them do a diagnostics; you can always say no to the repairs.

10-06-10, 02:50 PM
C&C, you been alot of help. Thanks. Local shops usually charge for diagnostics, so franchise dealers do too? Sorry this is my first purchase of this nature.

10-06-10, 06:39 PM
That's why I said bring it to a dealer. First they can check to see if the car has had the recall done, then since you are already there you can ask about the warranty (and if they would charge for diagnostics if you are not covered). Just talk to them and see what they say. Feel them out, as it were. Remember they won't/shouldn't shy away from warranty work (if in fact you are covered) as they charge the factory for reimbursement.

10-06-10, 07:35 PM
Thanks C&C, for anyone else who'd like to try to narrow down the problem, I've also noticed when switching from D to R or R to D, there is a jerk after a 1 second delay or so, then it finally shifts into the gear.

10-07-10, 11:24 AM
You could always change the rear diff fluid.. I had the recall done on mine and I still ended up replacing the fluid and adding a touch more Limited Slip add to the lube. Much better now.. No more chatter on turn and the slight bump went away. Been good for 15K miles now.

10-17-10, 09:28 PM
My mechanic savvy stops at the engine compartment. Where can I get the rear diff change, and since I am not completely aware of how the previous driver drove this car, should I get the tranny fluid change too? If so, where can that be done at too?

Car has 76k miles.

10-18-10, 10:27 PM
If you're worried, have someone check levels. Top off if necessary. Many trans services do more damage than good. Normal service interval is 100k.