: hard shifting



kcgemini
09-13-12, 05:57 AM
I have a 2003 deville with the northstar it has 172000 miles on it. Rides good but as its shifting from 2nd to 3rd its a hard shift unless u really lay into the gas. Would it b ok to change transmission fluid I've been told that once you have so many miles on a tranny u shouldn't change fluid. Any suggestions

Ranger
09-13-12, 12:15 PM
A trans fluid change can't hurt, but probably will not help either.

rodnok01
09-13-12, 02:43 PM
Older trans would develop leaks when you waited too long to change the fluid and would act up ocassionally. We had a policy that no more than 100k would a trans get it's first change or we didn't touch it(back in the 80's and 90's). With the newer trans and better fluid I haven't seen any real issues. If the fluid looks and smells good I would change it without a second thought. But as Ranger has said it prob won't help either. Sounds like a sticky valve to me.

stoveguyy
09-17-12, 01:02 PM
The lower valve body where the 2 shifts solenoids are located is very simple. The solenoids are almost identical and the plungers are also similar. I would be more inclined to think the pressure control solenoid is the issue. But that is under side cover and is a bear to change. A worn o-ring or leaky seal in any number of places could cause a rough shift.