Funky Transmission Issues

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

BigBlockJacen

TYF Newbie
Joined
Mar 20, 2022
Posts
6
Reaction score
6
ok group, long message incoming

Here is a puzzler for you but hopefully someone has had this happen. I had a new transmission installed last year in my 2002 Yukon with the 4.8l engine and it came with a 1 year warranty from a very reputable shop. A month before the warranty was up...the transmission started having 2 issues. 1) When you reverse out of the driveway, stop and place it into drive, there is a big delay and if you give gas too early, it thumps and jerks you into your seat. 2) The transmission shifts fine from first into second however the transmission will not shift from second to third when over 2000 rpms....under that it will shift fine. I took it back to the transmission shop and they have been great trying to fix it. At first they changed out the servo...no change. Changed out another servo and also the valve body...no change. They kept my my truck for 2 weeks and placed not 1 but 2 transmissions in it and it still did the same thing. They were now confident that it was not a transmission issue. They called a mechanic shop the owner knows that works on GM's and he said it sounded like the throttle body and to send it to him....they are known to cause transmission shift issues. I took the Yukon home and decided to do one thing before thinking of changing the throttle body...I installed a new Throttle Position Sensor on it to see if that might fix the issue....guess what....it STILL does the same thing.....thumps from reverse to drive and will not shift from second to third when over 2000 rpms. I took it to the mechanic shop that was recommended and after a week or so, he told me that everything was fine and it had to be the transmission....he even called the transmission shop back and told them it wasn't the engine.....I am at a loss. Has anyone ever experienced this? I have been down a vehicle for months. Do you all think it could be electrical?

Thanks everyone.
 

Rocket Man

Mark
Supporting Member
Joined
Dec 25, 2014
Posts
25,961
Reaction score
50,621
Location
Oregon
I’d be willing to bet it’s the transmission and when that shop told you they replaced it two more times they were lying, they probably are trying to get you past the warranty period. Take it to another trans shop and don’t mention that you have had it worked on at another shop until after they give you a diagnosis. If it’s electrical, there will be codes stored that they can read. If they do tell you there’s codes, have them write them down. Even if it’s mechanical in the trans there should be codes. Then go back to the original shop and have a little talk.
 
OP
OP
BigBlockJacen

BigBlockJacen

TYF Newbie
Joined
Mar 20, 2022
Posts
6
Reaction score
6
I’d be willing to bet it’s the transmission and when that shop told you they replaced it two more times they were lying, they probably are trying to get you past the warranty period. Take it to another trans shop and don’t mention that you have had it worked on at another shop until after they give you a diagnosis. If it’s electrical, there will be codes stored that they can read. If they do tell you there’s codes, have them write them down. Even if it’s mechanical in the trans there should be codes. Then go back to the original shop and have a little talk.

There are no codes that refer to the transmission. That is a good idea to take it to another shop.
 

rockola1971

Full Access Member
Joined
Dec 29, 2016
Posts
2,376
Reaction score
2,972
Location
Indiana (formerly IL)
Sure sounds like you have a valve sticking in your valve body OR a seal leaking past OR a check ball sticking in your tranny separator plate (Common problem of a worn transmission, the checkballs will peen the contact surface of the separator plate and get stuck there).
What color is your tranny fluid now? Nice and bright pink or more of a orange-brownish? Does it smell burnt?
 

Joseph Garcia

Supporting Member
Joined
Aug 2, 2018
Posts
6,394
Reaction score
8,325
Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.
 

Rocket Man

Mark
Supporting Member
Joined
Dec 25, 2014
Posts
25,961
Reaction score
50,621
Location
Oregon
Be glad that this happened BEFORE the warranty gave up.
Well..it first started acting up a month before the warranty was up, then they said they changed a servo, then they said they changed out another servo plus the valve body, then they kept it for two weeks while they said they put 2 other transmissions in it (cough) and it’s still not shifting right. I’d be willing to bet the reason they kept it for 2 weeks is to let the rest of the warranty expire, which will be their next move. Also I notice he said he’s been down a vehicle for months which probably means the warranty is now over. @BigBlockJacen is that shop still willing to warranty it?
 

swathdiver

Full Access Member
Joined
May 18, 2017
Posts
19,104
Reaction score
25,039
Location
Treasure Coast, Florida
NO 2-3 SHIFT OR 2-3 SHIFT SLIPS, ROUGH OR HUNTING

No 2-3 Shift or 2-3 Shift slipping, Rough or Hunting
Oil Pump (4) Stator shaft bushings scored or off location
Valve Body Assembly (60) 2-3 Shift valve train stuck
Gaskets or spacer plate incorrect, mispositioned or
damaged
2-3 Accumulator valve stuck
Face not flat
Chips in servo feed oil, orifice #7 in spacer plate
Mislocated valve body to spacer plate checkball or
checkballs
 

Rocket Man

Mark
Supporting Member
Joined
Dec 25, 2014
Posts
25,961
Reaction score
50,621
Location
Oregon
NO 2-3 SHIFT OR 2-3 SHIFT SLIPS, ROUGH OR HUNTING

No 2-3 Shift or 2-3 Shift slipping, Rough or Hunting
Oil Pump (4) Stator shaft bushings scored or off location
Valve Body Assembly (60) 2-3 Shift valve train stuck
Gaskets or spacer plate incorrect, mispositioned or
damaged
2-3 Accumulator valve stuck
Face not flat
Chips in servo feed oil, orifice #7 in spacer plate
Mislocated valve body to spacer plate checkball or
checkballs
But they tried 3 different transmissions and they all did it!
 
Top