4x4 klunking

[mbtech2003]

Hey all. My wife’s 2010 expo the 4x4 seems to be klunking slipping it goes into low range fine but going around corners it doesn’t bind up. Yes I’m on dirt not pavement I was in mud the other day and had a tough time with just the rear wheels spinning. And this noise. Did a transfer case flush. No metal. Did front and rear diff fluid changes no metal. Has new front end vacuum hubs. (OEM) I checked the front driveshaft. It’s ok. I guess it common on them to strip out. Anything else I’m missing here. Also in A4wd it seems to be the same. Thanks!!

 

[wk99]

I think the clunking sound when going into 4L is normal according to the owner's manual. Sound like your 4WD hubs are getting enough vacuum to engage if the front wheels aren't spinning. Check the check valve and the rest of the vacuum plumbing to ensure there isn't any blockage. Sometimes rust can build up in the vacuum lines. Best of luck.