Another thing to look out for are broken exhaust manifold bolts. This is apparently a chronic problem with the V10 motors. Long cast iron manifolds attached to aluminum heads. Differential heating and cooling can pull on and break the bolts.
Pull your doghouse out and check the bolts. My 2010 E450 Class C had 6 broken bolts with only 28000 on the clock. Calling around to RV repair shops I was quoted around $1500-2000 to make the repair. Lots of labor involved. Very little room to work in the van cut-away chassis.
So to make things short, I cut my losses and took the RV to Banks in SoCal and had them install their cat forward header system for $2000. They have all the equipment to make the installation and as part of the install, they replace all the manifold bolts. Problem solved.
Mike
