[deminimis]

Here's the deal, the '03 (and not sure of other years) idler pulley is an expensive SOB. There has also been a change in the part from Motocraft. There is no aftermarket option available for these pulleys. Its heavy cast steel. Not like the pulley itself will ever wear out, but the bearings will. Before you drop well in excess of $100 on a new pulley like I just did, think about this. The bearings (yes, bearings) are servicable. Here are the pulleys. The one of the left is the orig one off my '03. On the right, the much bigger new one. They both work on my '03 7.3.

Now, if you buy the newer one (why would you), you can't use your idler pulley bolt unless you change the right C clip for the style used on the left/orig/smaller pulley. If you don't do this, the flange on the flanged bolt will compress against the tabs on the newer C clip (the tabs with the holes in them for the c clip pliers) and the pulley will not turn. Here are the C clips (in this pic the C clip from the new pulley is on the left):

Now, here's where the rubber meets the road. Again, don't waste you money on a new pulley like I just did. The bearings for the orig '03 pulley are NTN 6203LUA. The bearings for the newer pulley (the big one) are NTN 6203LU. Very common bearings and approx $10/ea. Again, very common bearings used on Honda dirt bike wheels to Toro lawn mowers.

 

[anash13]

Just one question:
How the hell do you get at the pulley?
It is rather confined in that area.
How do you service this same pulley?

 

[deminimis]

That's the excitement of e-350 ownership. On my 08/2003 e-350 w/AC (7.3 of course), the pulley is top and near center. Guessing your's is elsewhere-perhaps under the tensioner setup? Your's might even be the stamped steel type? If so, then you'd just want to buy a Dayco, etc replacement pulley. Don't know why there are so many variations with these vans during the same production year.