Grinding Uphill

[ohioendocrine]

Hi,
When going up even a small incline my 2008 Expedition exhibits a grinding sound for about 1-2 seconds. This happens on a gear shift between 20-30 mph. The dealership agrees with problem but can not diagnose. Any ideas?
Thanks

 

[ELVATO]

4x2, 4x4, AWD (not sure what's offered for 08).

It does it when upshifting or when downshifting. Does it do it when there is not incline?

 

[ohioendocrine]

Thanks for your interest EVALO. It started grinding only on inclines but now will grind on flat pavement. 2WD or 4X4 makes no difference.

 

[ohioendocrine]

Excuse me for mistaking your name. ELVATO

 

[ELVATO]

I'm guessing transmission since it only does it while shifting. Check the fluid level and color of the transmission fluid.

Also, does it do it when shifting from 1st to 2nd gear? Does it grind differently (at all) depending how you accelerate? For example, if you gently accelerate, it should upshift early on (maybe at 10-15 mph?). And, if you floor it, it should upshift from 1 to 2 at around 40 mph.

EDIT: Actually, now that I think about it, didn't the 07+ have a 6 speed transmission? If so, then the mph I listed above will differ, but the idea is the same: it should shift at different speeds depending on throttle position.

Also, does it grind when you're slowing down?

 

[ohioendocrine]

As for the grinding. Not on a downshift. On slow acceleration around 25 mph as gear shifts but not if I floor it and at no other speeds.

Have had transmission fluid checked.

Tough case.

Thanks