The D has a "slobber tube" ((engine breather.crankcase ventilation tube) that is used to exhaust crankcase gases. However, this tube exhauts near the radiator and the result is that often some oil blowby and crankcase gases exit from this slobber tube and are deposited on the CAC (Charge Air Cooler). (See CAC for more details.)
As the deposits from the slobber tube mix with road grime, the result is an engine that overheats (initially when climbing grades). See Overheating for details.
The solution to this problem is to extend the slobber tube so that it exhausts below the radiator/CAC. You can either do this yourself with a length of heater hose or PVC or have Freightliner do this for you. Freightliner has issued a service bulletin on this - SUB #01/06. If your chassis is in warranty, Freightliner will pay for labor and material. If your chassis is out of warranty, Freightliner will pay for material only. It takes about twenty minutes to install. If your chassis is still in warranty, you may also want to talk with Freightliner in Gaffney and see if they will also pay for the cleaning of your CAC. You may want to speak with Kim R Hasse at Freightliner about this.
There are several different ways that you can extend the slobber tube - using a combination of PVC and heater hose, or just heater hose - but the end result is that you want the slobber tube to exit below the radiator/CAC. However, if you do this yourself, just be careful that the end of the slobber tube extension does not get plugged up by snow/ice if you drive in winter conditions - serious engine damage could result.
The DISCOVERY OWNERS ASSOCIATION, INC, was formed to promote the sharing of information and the camraderie of fellow Discovery motorhome owners. Membership in the club is limited to owners of Fleetwood Discovery motorhomes.