Sounds and feels like driving over rumble strips

Hi all,
I have a 2011 Tahoe 4WD with about 80K. Recently going down the freeway it felt and sounded like I was going over rumble strips (70mph). It wasn't constant, more like the strips in the center of two lanes where there is a gap. I pulled off at the next exit and it was still doing the same thing going only 55mph.

It was raining so it was hard to get a good look, but I did look around the engine and underneath the truck. But didnt see anything obvious. Whats odd is after sitting at the gas station for about 30 minutes I drove home and it didn't do it again. So I thought maybe it had something to do with the rain and tires. The tires are getting worn and are ready to be changed before winter.

I continue to drive it all week and it never done it again. However after about 5 days I parked in a different spot and noticed several spots of fluid in my normal spot. I look underneath and there is allot of fluid dripping down and around the front differential (picture below). I know its pretty recent as I'd just changed the engine oil 2 weeks earlier and there was no drips on the drive.

I'm trying to figure out if this is diff fluid or possibly transmission fluid. There is actually a puddle of fluid on top of the diff. It looks kinda muddy. I couldn't get a picture of it, but could see it. With the heat shielding I cant really see if there is any transmission lines above that might be leaking.

I'm thinking it could be transmission related, maybe it was leaking longer than this and low fluid is causing this? Or maybe the torque converter? Or maybe it is the diff.

How should I proceed to diagnose the problem?

Thanks

****Small update in reference to the motor mount comment:****

I set the phone on a garbage can to watch the engine as I tried the broken mount test. In my case it looks normal. Very little movement, nothing like in that video posted in another thread. Is it possible to only have the fluid leak out without being totally broken?

I also checked the trans fluid. To my knowledge it hasn't ever been changed. I let it warm up for 20 minutes and it was showing the engine at operating temp (Did not drive it, just idle). Color looked light pink and not dirty or burnt. However the level was just a smidge over the top cold mark. Is the trans still considered cold as it wasn't driven?

Guessing it is a blown motor mount.
I had a bad one, and it oozed on the front diff much like yours.

Not sure about the rumble strip feeling.. tcc slipping?

Thanks, I never even considered the engine mount. They have fluid in them? I had no idea. I suppose that would explain why the fluid looked so odd.

I watched a video of a guy changing the drivers side and it does look like possibly trans fluid lines run under it.

After watching that video I'm pretty sure you are right on the source of the leak. I suppose my next step is to fix that mount.

Small update:

I set the phone on a garbage can to watch the engine as I tried the broken mount test. In my case it looks normal. Very little movement, nothing like in that video posted in another thread. Is it possible to only have the fluid leak out without being totally broken?

I also checked the trans fluid. To my knowledge it hasn't ever been changed. I let it warm up for 20 minutes and it was showing the engine at operating temp (Did not drive it, just idle). Color looked light pink and not dirty or burnt. However the level was just a smidge over the top cold mark. Is the trans still considered cold as it wasn't driven?

I think your trans is still cold, there is a dic display that shows trans temp.
I think 160F is warmed up... Usually takes me about 15-20 minutes of driving around..

If it hasn't ever been changed, it's a good time to do it.
Even though I thought my oil looked decent on the dipstick, the first gallon that came out was pretty black!
(205k at the time, had one previous tranny fluid change on carfax at around 50-80k miles I believe..)

I've heard people like overfilling a quart or so..
Think I overfilled mine accidentally, but nothing came out the vent, so I'm leaving it alone!

Look above the front diff and see if you can see oil leaking from your motor, you might be fighting 2 different problems

Skylander said:

Thanks, I never even considered the engine mount. They have fluid in them? I had no idea. I suppose that would explain why the fluid looked so odd.

I watched a video of a guy changing the drivers side and it does look like possibly trans fluid lines run under it.

After watching that video I'm pretty sure you are right on the source of the leak. I suppose my next step is to fix that mount.

Click to expand...

The cooler lines running between the cursed driver's side engine mount and the block are for the oil cooler. The cooler lines for the transmission run down the passenger side of the block... also fun to deal with (at least for a 4x4).

Not sure what exactly the leak is from, but I'm curious how your wheel bearings are holding up? You'll get that humming/vibrating symptom with a bad bearing.

Skylander said:

Is it possible to only have the fluid leak out without being totally broken?

Click to expand...

Yes, mine leaked its fluid out about 6 months before it got loose.

George B said:

Yes, mine leaked its fluid out about 6 months before it got loose.

Click to expand...

It doesn't look like ATF, though. Wrong color and basically no way for it to drip on the driver's side of the front diff.

Check the power steering pump and lines?

Charlie207 said:

It doesn't look like ATF, though. Wrong color and basically no way for it to drip on the driver's side of the front diff.

Check the power steering pump and lines?

Click to expand...

???

I would bet $$ that’s engine mount juice.