Care finally runs well and passed inspection. So I can legally drive it at speeds. Noticed what feels like widely space rumble strips when coasting 2003 explorer. I am now trying to check all my fluids ... trans seemed a bit low (PITA), rear and front differentials seemed full... but should they be checked with the engine running or off??

 

differentials and transfer case can be checked with the engine off. no need to have it running as far as fluid level is concerned.

while you are under there it might be a good idea to check the u-joints in the drive shaft. a failed u-joint can cause a rumble like you describe, but it is usually noticeable on take off too.

 

I glanced at the u-joints but will look at them again...first drive after fluid check seemed good. But driving it at higher speed today. Fingers crossed!

 

something else came to mind ...

i haven't been under a newer explorer, but as i understand it the rear IRS is based off the same arcetecture that the old t-birds were ...

my old 89 'bird would do the same thing. there are some bushings at the front of the center differential housing for the bolts that hold the front portion of the diff to the sub frame. when those bushings go bad they can cause that same rumbling when you decelerate.

i'd get a pick for your but my t-bird sits about 5" off the ground ....

just a thought.

keep us posted!

 

lol Mine is higher... I will take a pic tomorrow and post it.

 

Speaking of bushings, I had a rumble on coast when the tailshaft bushing went out on my '71 Ford. The bushing came out of the housing and was pushed into the tranny. In the case of this Explorer, I would also check for excessive movement on the output side of the transfer case. Pushing on the driveshaft up and down where it mates with the transfer case would reveal any slop from a worn or missing (misplaced) bushing or bearing (not sure what's in side the transfer case). Not saying that's what the problem is, but it's easy to check.

Also, check for slop at the rear diff pinion.

If you have worn bushings/bearings in the transfer case or differential, a clue would be seal leakage but I would still check for excessive play.

Does the OP have any idea of where the rumble might be originating? Front or back, left or right?

 

Here are some inages of the Front Differential. Where would you suggest I look?

 

these pics look like your transfer case, yes? if you suspect the noise to be coming from the middle of the vehicle, i'd just start poking around at all of the attachment points. anywhere it is bolted to the frame is suspect. get on it with a pry bar (gently) and see if you can get any movement out of any of the attachment points.

in the second pic there appears to be a large bolt and bracket on the left directly across from the driveshaft. these are the places i would try to get movement from.

just go easy ... if you try to break it, you will. it's fairly stout, but just try a little pressure and see if you can get something to move.

do the same at the rear of the vehicle. follow the rear driveshaft back to the rear differential. it will be solidly bolted to the rear subframe. check those attachment points for movement as well. everything should be tight. look for bushings that may have shrunk.

in the pics i could find online, the explorer IRS is much different than the t-bird, so they may not be prone to he same problems.

 

In the second pic you can see the top of the large cross brace which I had to remove to drop the exhaust. Which of course temporarily dropped the front diff. Tempted to have AAMCO do a free check on it. It is too cold to be crawling on the garage floor right now lol.

 

Noise does seem to be from transfer case area. That being said... I have been doing more research on 4x4 and rumbles lol. The previous owner had put 2 new tires on the rear...the 2 on the front are older and have less tread. Therefore; the circumference of the front is less than the rear. The front axles needing more revolutions to cover the same distance as the rear putting strain on the transfer case. Could this be the cause of my rumble? and why would this only rumble while coasting? or would it always rumble and it is just harder to feel and hear while accelerating?

 

is this an AWD?

or does it have the Auto 4/4-high/4-low switches on the dash?

having new tires on the back of an AWD is bad Ju-Ju.

I actually just got rid of my AWD explorer because of problems with the AWD transfer case. mine would only really be noticable when turning though.

 

it is Auto High 4x4 and low 4x4, but some documentation refer to it as AWD. When I hit the Low 4x4 the light flashes then goes out. so not sure what is up with that yet.

 

i haven't had one with the auto 4, but that may be normal.

in order to go into 4-low, the transmission has to be in neutral, and the vehicle has to be stopped (or nearly so).

having drastically different tread depth front/back can still cause problems with the auto-4. Might be worth disabling it and taking it for a drive to see what it does.

might be as easy as pulling the fuse for the transfer case (labled control trac?). You'd be stuck in 2wd but it should eliminate the difference in tread depth screwing with the transfer case as the problem.

maybe someone else can chime in with a sure-fire way to disable the auto-4?

 

The low 4x4 was operator impatience lol. I had to wait 10 seconds for it to go solid. One attempt I hessitated in 2nd gear and it turned off lol. If I am patient and careful it seems to work fine in 4x4 low. I am going to get tires for the front and try to keep the circumference very close. I really do not want to wear out my transfer case just because of mismatched tires.

 

Problem solved! I bought 4 almost new Michelin's. Drives better, no more rumble! Now I am still curious as to what the intermittent banging is from somewhere near trans. AAMCO says trans is fine.