Engine kick back on start up

[Got it covered]

Here is the second part of my original post :

2000 Tahoe, 5.3 4L60 e, NVG246
Upon first start of the day, (open loop) there are never any issues with engine kicking back, just a smooth start up regardless of ambient temp. But after the engine reaches operating temp (closed loop) re starting the engine will often create a slight drive line clunk (either in park or neutral, foot on brake or not) the clunk can be slight, or quite severe, and tends to move the vehicle rearwards. Doesn't happen with every restart, but is always ever so slight. I tryed adjusting the neutral switch along the diver frame rail under driver door, disconnected the shift cable at transmission to make sure shift lever was fully in park, rocked the truck forward an backwards to make sure the pawl was fully seated, still happens occasionally
The only thing (s) I have done is replaced the original gov-loc differential with a LSD that I rebuilt and it is right. The transmission was rebuilt and upgraded by a local trans only shop. I don`t recall it doing this before the transmission being rebuilt, could be wrong One other thing, the rear driveshaft was replaced due to damage while replacing rear joint used shaft. could it possibly be yoke on shaft

Any input would be appreciated

 

[6speedblazer]

Sounds kind of similar to this bulletin

INFORMATION Bulletin No.: 08-07-30-026

Date: May 22, 2008

Subject:
Information on Slight Vehicle Movement In Park At Start Up After Cold Soak Models:
2009 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn)
2009 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X with Automatic Transmission

Some vehicles may rock or move slightly forward or rearward while in park at start up after cold soak. This condition may be accompanied by a clunk noise. This is a slight movement that is more often seen visually, rather than felt, when viewed from the outside and using the auto-start feature, if equipped.

This slight movement is due to the residual transmission fluid in the clutch packs that creates a partial apply on start up. This movement is stopped by the parking pawl and/or transmission fluid exhausting completely from the clutch packs.

This slight movement has no adverse affects on the transmission and no repair should be attempted. This condition is normal. This can be verified by comparing with another identically built vehicle under the same cold conditions.

To prevent this condition from occurring, the parking brake should be utilized as per the Owners Manual recommendations anytime the vehicle is parked.

 

[tom3]

Just curious. What does it do if you start it in neutral?

 

[Got it covered]

Sounds kind of similar to this bulletin

It does, doesn`t it. Especially seeing the transmission is fresh. Hard to believe with the severity of the clunk (not often) that damage wouldn`t occur. But the article refers to cold soak, cold start? mine does it warm start only

 

[Got it covered]

Just curious. What does it do if you start it in neutral?

Same as park. One thing I did do this morning, I purposely parked in a parking space with the front tires trying to climb the curb, held the brake while putting in park, parking pawl engaged . went in store got my shopping done, started truck, nothing, no noise ! tried it 4 times. Nothing. My thoughts are it`s most likely drive line related, there`s slop somewhere and since the driveshaft was replaced with a used one I`m thinking yoke is worn badly

 

[LsHart]

As tom3 stated, start in neutral and see if it's doing it then. If not then transmission shop bound!