Hi, I recently bought a 2011 Express 1500 wi the 4.3L V6 and I assume the 4L60E transmission which I'm now worried about.

The van has ~120K on it and drives very nicely, seems to shift fine, and from what I know got regular maintenance. The noise is a knocking kind of noise, not super metallic, not super loud. It only comes after the transmission has been well warmed up. I happens whether the vehicle is moving or not, but only under some load (ie under acceleration or stationary in gear with foot on brake and enough gas to go to 1000 or so rpm.) When driving, engine and road noise overwhelm the worrisome noise once over about 20 mph. It seems to happen at 1/3 to 1/2 the engine rpm I would estimate. The fluid looks/smells pretty good, but not pristine.

One more thing may that may be totally unrelated but who knows. There's a minor engine oil seep from the engine/transmission juncture... Rear mail seal?

Any thoughts would be appreciated. I was thinking of dropping the pan, taking a look, putting in fresh fluid/filter and hoping to get lucky with that.

 

If you dont know when it was done, probably wouldnt hurt to drop the pan, change the filter, and then you know what you have in it for fluid.

Check out your driveline to see if the universals are in good shape, any carriers are moving freely, splines are greased/lubed, etc. Or see if you have a heat shield that expands when you are warmed up and is making contact with something causing it to knock....

 

Thanks, I'll do the fluid as soon as I can get the parts (I live in a small town so may have to order them). Since it does it when the vehicle is stationary, that should rule out the driveline, right?

 

Sorry, I had missed the stationary part when I read through your post.

So is it making the noise if you are in park/neutral and give it some gas? Or just when you are starting to move forward from a standstill in drive?

Any auto parts store should have what you need without needing to wait too long to get it in.

 

Not in neutral, just when in drive or reverse and I give enough gas to make it move or, no difference if I keep my foot on the brake and make it try to move.

 

I changed the filter and fluid, and unfortunately the noise is still there, a bit louder if anything, though that's hard to tell. Any thoughts appreciated.

 

Here's a recording of the noise. I made it with my cell phone on the garage floor below the transmission, in gear and giving it enough gas to get the engine up to ~1100 rpm (with other foot firmly on brake -- vehicle not moving).