Front left axle sounds angry when 4WD engaged

[jrpentolino]

Our Eagle was nesting in a barn for 20 years, and then sold to me a month ago. Since then I've got her running like a top and just tore into the select drive. The vacuum lines beyond the steel were severed or missing altogether, so once we repaired all of that it worked like a charm.

I have only tested the select drive system while up on 4 jack stands, all tires off the ground. But I noticed when I shifted into 4WD and let the clutch out, there was a scraping / grinding noise coming from the front left axle area. That's the best I can do to describe this as I was in the car while my daughter was confirming that indeed the tires were rotating under power.

The car doesn't make that noise when driving in 2WD, as I've put about 100 miles on her since I got her running (but before I got the select drive working).

The next step is a new clutch, and complete suspension and brake rebuild. So as a matter of course I'm going to replace the wheel bearings and half shafts. But that noise was a little disconcerting.

My questions is...Could that possible be something in the front axle I need to look at?

If the likely culprit is the wheel bearings (unlikely as it doesn't happen in 2WD), or a half shaft (maybe??), then this will get sorted out in the front end rebuild. However, IF there is something likely going on in the axle then perhaps I should pull it while I've got the front end out.

Any advise is definitely welcome!

[AMC of Houston]

Sometimes with the suspension unloaded (off the ground and hanging) things will rub that don't rub while on the ground.   Tire rubbing on something?   Crusty brake rotor or hard pads?   CV joint angle too sharp??   Get a mechanics' stethoscope and track it down (piece of rubber hose stuck in your ear also works like a scope).

[jrpentolino]

Sometimes with the suspension unloaded (off the ground and hanging) things will rub that don't rub while on the ground.   

That makes perfect sense. Thank you! I have a mechanic's stethoscope and I'll hunt it down that way. I didn't even think about noise because suspension is unloaded. I'll try and sniff it out but I'm not going to worry too much at this point.

[jrpentolino]

Update: AMC of Houston was correct! Once I got the Eagle off her perch (Jack stands) and running on terra firma she ran like a bat outta heck. No noise. Took her up to 85mph on the highway in 4wd with no noise or issues. I’m beginning to love this car.

I wonder if there’s any chance I can buy my daughter a Mercedes so I can keep the Eagle?? Somehow I doubt she’d take that deal.