Torque Converter noise

[nhkid]

Question about ATF fluid in a 2000 Silverado 4X4 5.3, 3.73, w/36K.

I have a torque converter that makes a noise like you are running over rumble strips on the highway, when it shifts into overdrive between 37-47 mph. After being to numberous dealerships and being told that this is a normal sound due to the engineers developing the truck to achieve the best gas mileage possible. I plan on switching to Mobil 1 synthetic atf very soon, and am wondering if this will quiet down the chattering torque converter plates. I was told by someone that 'Lube Guard Red' will quiet that noise down.

Any thoughts on this?

I have been just running the truck in D3 until I am running at least 50MPH.

 

[rpn453]

Strange. That's a lock-up torque converter so there's no relative motion between the plates at highway speeds. What part is chattering and why?

 

[novadude]

Sounds like a classic case of shudder to me. Go here for more:

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=24;t=000084

 

[Bub]

The 4L80E in my 2500 HD does the same thing, but I just mash the gas a little and the TCC locks in firm. I believe the gas milage explanation, mine goes into OD at 30 mph and then hunts for the right gear, so just like you I use 3D until I get on the highway.

gas prices just topped 1.69 for regular down here, looks like It's time to pull the Z28 back out in hopes of better mileage, had hoped I would'nt have to use it until spring.
Bub

 

[nhkid]

I have changed out my ATF fluid form what was put into the tranny from the factory to Mobil 1 ATF and also added Lub-Guard Red.

My question is how long does it take for additives to take effect?

 

[wtd]

I don't want to worry you, but the 4L60E in my 98 ext-cab Z71 didn't like the Mobil 1 ATF. It started to cause it to slip after awhile. I drained and refilled a few times with conventional Dextron III and the problem went away. Some people have reported no problems with the Mobil 1 ATF in this tranny and hopefully that will be your experience.

Wayne

 

[nhkid]

Thanks for the heads up Wayne!!