Hello to everyone im in need of some help, well turns out that last summer i got this 1998 lincoln navigator, with the 5.4 4x4, well its been a nightmare all the way around, first 4x4 did not work so i took it to a local shop they said the actuators are bad im assuming transfercase area, ok now the 4x4 is working but now i can hear a metal on metal sound coming from front end, mid section, i check the transfercase to see if it had oil and it did did not see any excesive metal shavings, took it back to mech he said the front differencial was bad, ok replace it,ok but i still hear this metal on metal sound not very lound but enough to be noticible plus it will come to a stop on its own once you let of the gas it slows down and finally comes to a stop, i dont think this is right should not do that the mech said this is normal for a big truck like this so i went to local car lot and tested same model as mine and did not make the same noise, i do have the same tire zise all the way around and yes i verefied that rear and front diff are same ratio, its winter now and im using the 4x4 but it is very uncofortable listening to it and now the aw4 part is blinking, 4x4 dont work on that only on 4hi and 4lo please help with any ideas, and just in case, i dont think this has anything to do with it but i do have the check susp light ? is everything seems fine not sitting on frame or nothing pump is not pumping all the time but does this have anything to do with the 4x4.
Thanks in advance.

 

It could a front hub (wheel bearing), a CV joint, u-joints in the front driveshaft, a brake rotor scraping it's debris shield, or the front driveshaft sliding portion.

 

Just want to add the possibility of stuck brake calipers.

 

Of course you did.
No need to be correct as long as you get to say something.

 

the thing is that it only does it when it is in 4x4, but when in 2h its normal, so i dont see a caliper or wheel bearing causing the noise, the other thing is that, i took the front shaft off and i put it on 4x4 and it dont make the metal on metal sound but then again there is no load on the transfercase and front diff with the shaft off, i feel like smashing this thing any ideas on the check susp light .

 

A load or lack thereof is irrelevant, the noise is coming from the front drive shaft. The shaft telescopes and needs to have grease inside of it. If the grease is dried up that could be the source of the noise. Other than that, you probably just need to change the u-joints.

 

Alloro,

I have a question about that. How do you know the difference between U-Joints needing to be replaced and upper and lower arm bushings needing to be replaced from a sound/noise perspective. I have 99 Expo with 190K and I have a tremendous amount of rattling that comes from the front end (both sides) when driving down rough roads. It even kind of makes the noise when making sharp low speed turns. I have recently replaced all 4 shocks so I know that isn't causing the noise. I always figured with the years and mileage it was probably the bushings.

Thoughts?

 

It's more likely the front and rear sway bar bushings are worn. I'm talking about the ones that hold the bar to the frame, not the ones at the end of the bar. Although you should inspect those as well.

The first symptom of worn upper and lower arm bushings is steering wander. You'll get the wandering, or an inability to keep the truck driving in a straight line, long before you'll get any rattling sound out of them.

 

sorry for my ingnorance but replacing u joints would be in the rear driveshaft only right.

 

Just the opposite, you'll want to change the u-joints in the front drive shaft since removing it caused the noise to go away.