Shudder under load in 3rd and 4th - 4L80e

[mgray]

Just had the fluid in my transmission flushed(they just disconnectd a cooler line and ran the fluid out that way). Now under load(over2000rpm) there is a noticable shudder going into 4th and a lesser noticable one going into 3rd. 2nd is nice and firm and torque converter lockup is smooth.

Don't remember it doing this before the flush. Fluid seems a little high when hot, but could be ok.

Any idea?

 

[Acesneights1]

Make sure it is not overfilled. Overfilling will cause aeration of the fluid and hydraulic pressure to the apply pistons clutches etc etc. IIRC the fluid is checked hot with truck running in Neutral(not park) but check your owners manual to confirm. Overfilled by even a little will cause alot of problems.

 

[mgray]

Weird thing is, I checked the fluid level cold today and it was way high!! Like over the little bend thing on the stick. Drove it and everything seemed fine, checked it warm and it had gone down a bit I think, but was still high.

I'm hoping it's just overfilled, but how can it be higher cold?

 

[Suburbank2500]

Probably because the fluid is sendt aorund in the system, as with the engine itself, level aint stable until the oil settles..

 

[Acesneights1]

Drain to proper level. If it's overfilled you can damage the trans.

 

[WarWagon]

Check level with engine running. Otherwise the Torque Converter etc. can drain into the pan... The level not running is worthless: has oil or not.

Start it cold. Shift reverse, drive, then park. Should be around full cold. Drive it 15 min and then check level. Should be around full hot. See any foam on dipstick?

Check for loose connectors. Check the drive shaft and center bearing too.

 

[mgray]

Ok thanks guys. I did pull some fluid out when it was cold, down to the hot mark cold. Drove it on highway for 30 mins, came back, went thru all gears, checked hot. Was at cold level!!

I know transmissions are supposed to be checked hot, but every other one I've checked, the cold level was where it would be cold, and hot at hot. This one seems backwards!! My other buddy who has a '98 gasser sees the same thing when he checks cold. If GM knew fluid would drain down when cold, why not put the cold mark above hot?

At least I seemed to have gotten rid of the shudder, must have been overfilled.

Before I drained some, the cold level was above the bend in the dip stick. Look s like I'll know have to add a little bit to bring it to the hot mark.