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AW4 making noise on accereration?

CobraMarty

NAXJA Forum User
On the new jeep with 4.0 and AW4, under less than 1/2 throttle everything is fine, idle is fine, shift thru all the gears fine.
The problem is under hard acceleration in 1st gear it makes a metalic noise, like a piece of metal is touching the ring gear, almost a 'ratcheting' like noise. It seems to still be accelerating during this noise and once shifting into 2nd the noise stops.
Checked the flex plate inspection cover, flex plate looks good and bolts are tight, no muffler or cat rattles, fan not hitting the radiator, motor mounts look good.
This sounds bad, ? 1st gear splines slipping, ?torque converter noise, ?something loose inside of trans?
 
sure it's not a ujoint that's in the beginnings of failure?

if it's got a rusty cap or something they make those noises when you get on them hard.

Might want to pull the rear driveshaft and rock with the front wheel drive to isolate it as trans or something in the rear driveline.
 
That would be sweet if it is just the u joints. With 140k on it maybe just change them out with new.
 
OK, looked closer.
It would make the noise while 'torque braking it' at a stop, and the noise was coming from the front. Popped the hood and it all looked fine. Did it again and watched the engine move FORWARD about an inch and the fan was hitting a small piece of metal and not the radiator, thank goodness.
Time for new motor mounts. So much for the 'motor mounts look good'.
 
Sounds like the transmission mount is completely busted too if it is moving forward!!!!! The engine mounts stop it from rotating mostly (I think) and the Tranny mount should stop forward movement? Mine was missing the damn Tranny mount bolts!!! PO BS. Actually I suspect all 3 need to be bad for a straight forward shift forward 1"?
 
if doing the motor mounts you should probably do the trans mount.

they work in conjunction, and one bad mount in the group will make the others wear out faster compensating.
 
Haven't looked closely at the trans mount but plan to replace all 3.
Will be ordering all 3 mounts, just trying to decide on stock type($60) or poly($200).
 
I'd go with stock type.
I'm not impressed with poly's NVH (noise, vibration & harshness) characteristics. Highest quality rubber you can get for the $$ you want to spend, is my opinion.
If you don't DD it and want maximum stiffness / don't care about vibrations, then go poly.
 
Bought stock like this-off ebay $50 vs $200 for poly.
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I use Brown Dogs engine mounts with the rubber inserts, and I have a poly trans mount--seems to be a good combination.
 
2 deteriorated motor mounts and the trans mount was ok. Replaced all three with stock. No forward movement now. Good note trans seems to work and shift fine.
 
I actually starting have the same noise problem Christmas night. I thought it was just loose lug nuts, when I found them a little loose (confirmation), but part of the noise stayed on straight forward acceleration only, at 15-25 mph in 2nd gear at about 50% of WOT.

Yesterday it was warmer and I could not hear or feel the noise at all, no matter what I did. It was a lot colder the night I heard it. I suspect it may be early signs of a worn front axle U-joint, passenger side, but I am hoping it was just tire noise, or something simple. This is my 87, 4WD. The loose lug nuts were noisy on turns, and that noise is gone.
 
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