4405 T-case thump... More then normal

[skoal_mint]

I'm just wanting some info guys..98-99 ford expedition

I had this customer about 2 months ago, and the t-case was engauging like crazy. So, another mechanic says get new t-case. (I can't convince him that its not the problem, im just a "apprentice") So it gets changed, and seems so be better... ok, done.

Well I take off for school, went back home for the weekend and customer was their compaing its getting worse, same as befor.
When you hit the gas you thumps for fast and long for about a block, not the normal thumping that happens maybe 3-4 times

So how or why would it be doing this? speed sensors, is it duty cycling, is it all computer, if so what does it get its singles from? tps,wss,maf

 

[IZwack]

Well first of all, I would remove that front driveshaft and then take it for a spin to see if this thumping goes away. If it does, then the 4wd is definitely engaging and its time to look at why its engaging (different tire sizes, bad sensors, and so on...) -- or the front driveshaft has a problem (U-joint, CV joint, balance, etc..). If it doesn't go away, then the problem isnt 4wd related and is probably somewhere else (maybe the axle or something).

One question: are you sure its a 4405? Cauz the 4405s I think were unique to the 4.0L.

 

[skoal_mint]

not too sure about the exact one, but it looks the same as my explorers.

I don't think I would hear the noise because their wouldnt be any load to make the "thump"

Mitchell has some test to do for the replay and computer... I believe theirs a hall effect sensor somewhere too

I will check the tire size tho... I'll will also mention the brown wire mod to the customer, but he would have to do that on his own