New P38 owner - Front axle or hub bearings?

[leomd]

I just picked up a dark blue 1998 P38 a few days ago (sold my Mark III about a year ago). I cant say how much happier I am with the P38 then with the ole' beast...buts that's an entire different conversation.

Trying to get her back into shape and listening to a strange gear whine/slight grind when I let off the accelerator pedal. I also think (but could be wrong) I hear a bit of the whine/slight grind when I get on the accelerator as well. When I'm neutral on the pedal (neither accelerating nor decelerating) I hear no whine at all. I also notice when I come off the accelerator pedal at speeds there is a bit of a rock back and forth (play in the prop line or diff perhaps?). I usually do not hear the noise during the first few minutes of driving from a cold start. I have also noticed a drip from one of the nuts on the bottom of the axle case.

Do these symptoms give away the culprit or is a combination of items. Does this sound like low axle case oil? Bad bearings? Seized u-joint? I am confused by when the accelerator is neutral at any speed(not accelerating or decelerating) and it is totally silent. Should I be concerned about the condition of the front diff?

Thanks in advance for any ideas.

[getlost4x4]

check the fluid levels and color. if its silver its probably time to change it. it should be level with the fill hole when its full.

[wreckrunner]

With any recently purchased vehicle, regardless of whatever the dealer or DPO told you, it is best to change ALL fluids and filters just for peace of mind or even to enable you to start your own service and maintenance regime. Don't forget to include grease the buggery out of the prop shaft UJ's and sliders!

[leomd]

Great advice, and already checked off the front diff oil change. The oil was a bit silvery at first and then looked normal color so I assume there is typical wear. Unfortunately, the diff oil change did not remedy any of the noise. I hope the tranny is not shot, it seems to accelerate fine and drives,shifts perfectly but I still hear that whine when I let off the accelerator pedal. I don't think its the hub bearings as the sound would be constant or am I wrong to assume that.

I will do a rear diff, oil change, prop shaft grease and transmission fluid change soon - see if that helps. Since I have 150k miles I will prob change the bearing hubs out when i do the brakes.

[getlost4x4]

did you check the u joints for wear? is there any side to side play? Start with easy stuff. Is it definately coming from the front axle.

It could be as simple as axles and CV's, driveshaft problems, or bearings.

you can check the front wheel bearings for play when its jacked up and the wheels are off the ground.

[sydneyman]

hmmm i could have sworn i posted in this thread... oh well i'll try again. +1 on greasing the shafts, it'll take 5 seconds to get all of the zerk fittings...

oh and welcome to the P38a side!

[RRToadHall]

hmmm i could have sworn i posted in this thread...

You did. Your off topic hijack was moved to it's own thread

[Hoges]

Don't rule out noise in the transfer case. I heard a distinct whine when backing off the throttle...I wondered about the front diff, checked wheel bearings etc and finally settled on the T/F case (because it was easy to change the oil! ). The recommended fluid is DexronIII auto trans fluid. However, having searched the posts on this site I discovered that the better choice is Mobil Agrifluid 424. I'll vouch that it's terrific stuff for transfer cases but DON'T use it in your auto transmission! Google it and get the specs. ..... My T/F case doesn't 'whine' anymore (well not with the carpet in place!) it has been quiet and smooth now for 40,000 + km.

[sydneyman]

You did. Your off topic hijack was moved to it's own thread

ahh thats one mystery down... but did you hide my powerdrill battery yesterday too?


i thought of that but couldn't find any new thread and thought since he mentioned it in his post it wouldn't be too offtopic so i wrote it off as dementia. switching to PM.

[leomd]

UPDATE - I changed the oil in both diffs, tranny, engine and also TF case and replaced all filler and drain plugs with magnetic plugs -whine is still there.

I noticed that when the front wheels are in the air ...I turn a wheel there is about 2 inches of play (in outer diameter of tire) before it turns the other wheel - I noticed there is a bit of play in the rear diff as well. Does this indicate the diff is bad if there is any play at all? The car has 152k on it, is it normal for diffs to go at 150 miles or is it more likely they were not serviced properly? Either way I suspect the bearings are making noise too because they seem to rumble at low speeds. I notice a drive train lag when I come off or get on the accelerator, there is definite play in the drive train...and from my inspection the play in the system seems to be the front diff and also the rear diff as well. Bummed It appears I need to replace both diffs and front bearings to make her drive right

[97p38]

now that you have the truck jacked up put jack stands under the axles and run the vehicle at 30 mph and listen for the noise with a long screwdriver or stethoscope. Pay close attention to the differential pinion bearing area.I suspect that you have worn differential bearings. Side and pinion bearings can be replaced without replacement of the ring and pinion. This is quite common at your mileage. If you plan on upgrading to lockers or larger tires and 4:10 gears this would probably be the time to do it.When road testing for wheel bearing noise it can be helpful to determine which side by listening for a noticable sound difference when turning slightly from left to right.The side load change on the bearing usually make the noise more noticable.

[leomd]

When I turn the wheel at speed ever so slightly to the right there is a definite noise (almost sounds like a rubbing brake) then goes away when I straighten her out. I was assuming this may be the left bearing. With the amount of play in the front and rear diff (I'm not sure if there is any allowable play at all) would indicate to me that things are worse then just bearings - the outside of the tire moves about 2 inches before the other tire engages.

I have brought her in to a local Indy shop here in Miami and they "say" that the diff is gone and they cant tell the condition of the bearings until the diff is replaced repaired. Sounds suspect to me. Either way I will attempt to pull the diffs and see whats going on and update - thanks for the comments.