1998 GMC C1500 Why does my transmission shift so hard after

Tiny
TREND1234
  • MEMBER
  • 1998 GMC C1500
  • V8
  • 4WD
  • AUTOMATIC
  • 113,000 MILES
1998 GMC K1500 Sierra SL 8 Cyl 5.0L

( 4WD automatic transmission 4L60E )

my truck shifts in to 2nd gear hard under realy slow acceleration and under normal high acceleration and um when my truck has been sitting for a while like over night or more than 10 hours the problem comes back the next time I drive it but the problem gose after a couple stops and goses then problem gose away ive had my truck for three years and its never done this before I have done tranny flush with ( no solvents ) new filter the pan cleaned out new ATF dexron III new gasket and had the tps check and a trans scan done at aamco transmission and all good no codes coming up but still having the same problem aamco said it was normal but I no it is int because its never done this before I use to be able start it and go to work not crazy like. The problem started about 6 months ago starting of winter and the temps outside right now here are in the 50s and lowes are in the lowe 30s it seemed to be softer when it was colder or it just goten worser I dont no if its the tranny or something els I did have a noise that souned like a yoke during the sumer berfor winter but its gone away. O and before I had the tranny flushed I tried lucus transmission fix and trans x additives no good and I disconnected my battery pulled out the main car computer for an hour and pulled all the fuses out no good thair ether I let my truck warm up for 3 min problem still thair. Help

o and the shift stays hard every time tell I do a few stop and gose like ten time then gose away ^^^^

__ I got it flushed on monday 02-08-2010 the hole works new every thing new filter new atf fluid pan dropped and cleaned out. New gasket __

o also I had the 1-2 servos checked they are fine had the 1-2 shift accomulator spring replace and new piston seal put in also had the TPS checked fine thair to all fine

i gone to two mechanics they said it was normal then I went to a therd he said thair somthing wrong a delayed shift /engine he said have the engine look at

im gone to anothe place to have a the (VSS) look at

what should I do?
pcm flashed?
have it put on a dyno and have acm monitored?

. Before I had the tranny fluid changed it looked good and had no burnt smell.
and if I go realy realy slow thair no jerking at all then if I push the gas it jerks hard

my engine oil is milky lke choclate and my radiator fluid gose down some times o and I put in a engine restore addittive in it would the make it milky I dont no plz help
Do you
have the same problem?
Yes
No
Thursday, March 25th, 2010 AT 8:30 PM

1 Reply

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
As far as the milky looking oil goes, have your engine pressure checked you probably have either a head gasket or intake gasket leaking antifreeze into the oil. That is not a good sign. As far as the trans goes, it sounds like a valve sticking or servo sticking until it warms up enough then it breks itself free. Most of the time if you have over 100,000 miles on the vehicle it's not recomended to change/flush trans oil as the new oil eats away the clutchs inside the trans. But I would keep driving it until it gets worse as in time it probably will then it can be fixed correctly.
Was this
answer
helpful?
Yes
No
+1
Friday, April 2nd, 2010 AT 8:02 PM

Please login or register to post a reply.

Sponsored links