carboncow

OK, so I determined I needed a check valve in the system so I added in one which solves my issue of the noise when in 2WD mode trying to engage. I added in the 2nd standard check valve I saw on many posts. My dragging didn't happen very long or often before I figured the out, but now...

But now I'm wondering if I need the other check valve AL3Z19A563A (3 port) or I have damaged splines.

This week I was pulling a 8000lbs boat/trailer in wet and hilly terrain so I put my 2013 Lariat in Auto 4WD mode. I then noticed some terribly concerning sounds under load and/or going up hills. I thought it was engine/turbo related before it dawned on me the IWE may be spinning in the hub spline or something else is going at work. I switched back to 2WD mode and it was gone. Put it in Auto 4WD and the concern returned. So the solution for making the sound go away is the opposite of before. When I hard the grinding before in 2WD move I shifted to AWD to make it go away. Something is still not quite right.

So let's assume the spline is spinning/skipping in there in a way to make a concerning sound/growl...but I cannot tell which side.

How does one figure out which side is offending?

I'm going to also replace the original 3 step check valve to make sure that isn't an issue since the 3rd port runs to another vac resouvour but this is clearly related to the IWE/hub issue.I've also seen mentions of replacing solenoid but I don't thin that is my concern since it seems to hold vac in 2WD mode, please correct me if I'm wrong. I'm all over the place here!

Any commend or thoughts or knowledgable and helpful people is appreciated...otherwise, not so much...

paintballdude05

Do yourself a favor and get a vacuum pump with a gauge. That way you can test and isolate all the components of the system to find your issue. The FSM has specs and procedures for this. I was having issues with the system on my 2008 and the vacuum pump was essential to solving my issue. I ended up having some clogged vacuum lines (mud) along with a dead IWE.

Blue2016XL

Since the noice goes away in 2WD, he doesn't have an vacuum leak.

Sounds like one or both of the IWEs are bad. You could jack one wheel up and turn it by hand to see if you hear/feel anything. Then repeat on the other side. Other option is to actually do a visual inspection.

carboncow

thanks...this makes total sense but I figured it would not work as it takes the he’s y load of the boat/trailer to trigger it. Can it it be pretty obvious with no load turning it?

is there any way to inspect w/o disassembly? Pretty obvious with metal particles or such?

Blue2016XL

Depends on how bad it was grinding. If enough, you would definitely see some sort of grinding but, I do believe the IWE gears are some sort of plastic. So, you'd see more damage on them than you would see metal shavings.

You may not feel anything by what I suggested as it may not put enough load on them. Worth a shot though.

Another thought is if you have something that you could record noise next to each wheel, cause it to happen and then see which side is louder. Assuming you can pick it up over the rest of the noise. I know they make something that you can use to trace noises but, I can't remember the name of it now. @Rnlcomp uses/used them and he would know the name.

carboncow

thanks, all good intel. I’ll dive back in deeper when I get some time. Truck has been apart to much of late...need a breather. Since it’s fine in 2WD I got som time.

RLXXI

Chassis ears.
.

jdunk54nl

Did it just make it for a few seconds or for a long time?
If just for a few seconds, it might be the clutches engaging the AUTO 4wd system when it senses it needs more traction. I know my truck will make that sound if I am on a slippery surface and stopped and try to start. Truck will be in 2 wheel mode and try to shift into 4 wheel mode when it senses the back tires slipping. Under load it grinds in the clutch area. I now just use regular 4H so I don't have to hear that sound.

4 auto is great when it is just a low load normal driving situation.

carboncow

thats a good question/point. The grind goes on with load as if it’s slipping or trying to engage. I was actually afraid to put it 4HI with that load and speed on head pavement...thoughts?

it was very much a feel through the truck that made it feel like a trans/diff (as you mention) but that sound was very much the sound the IWE made when it wasn’t holding vac in 2WD. So sam3 sound but more a strong feel through drive line.

Blue2016XL

Don't run 4H on dry pavement unless going in a straight line. You will need to switch in and out as require if not using 4A.

As to the noise in 4A, I can’t speak to that as I don’t have it on my truck.