P38 Heater Core Replacement
Wet Carpet Symptoms and Causes
Replacing the Entire Heater Core (LHD Vehicles)
Photo: Range Rover 4.0/4.6/P38 heater core (illustration courtesy of Atlantic British)
Wet Carpet Symptoms
When the front carpets in your 4.0/4.6/P38 Range Rover suddenly gets wet, it can be due to several causes. It does not necessarily mean the heater matrix has failed (as was notoriously the case on the Classic)! Much more likely, it is simply a matter of either blocked air conditioning drains or that the heater O-rings need replacing. So check these out first, using the following diagnosis procdure:
The O-rings are located inside the passenger compartment under the right hand side of the dash, so if you notice fluid in the right hand footwell but not the left one, this is a very likely cause. This matter is dealt with on the Heater Core O-Ring Replacement Page.
If replacing the heater core O-rings do not solve the problem, you can be fairly sure the heater core itself is to blame.
Heater Core Replacement on LHD Range Rovers
Thomas Dirksen (who pioneered the abbreviated procedure described in the O-Ring replacement page) also had occasion to change the entire heater core. Officially, replacing the heater core requires the removal of the entire dash/fascia. However Thomas found a shortcut method that makes this operation much more bearable. "After removing the glovebox, I drilled through various spot welds on the dashboard frame. Then I partially sawcut an "ell" bracket (that helps support the dash) and gently bent it out of the way to remove the heater core. I then lapped to pieces of metal and riveted the frame back together, and then riveted the spot welds I previously drilled. So it is possible to change a p38 heater core without removing the dash fascia."
In September 2008, Chuck Brazeau went through the above diagnostic
sequence and arrived at the inevitable conclusion (heater core failure)
after owning his 2002 Range Rover only 2 weeks. Chuck read about Thomas
Dirksen's procedure and decided to try it and fill in the detailos for
us. He has kindly contributed the following complete description of the
shortcut procedure he followed to replace his heater core.
Dismantling the Passenger (Right) Side Dash
The photo below shows how far the passenger side interior needs to be disassembled. First, the glovebox is removed. The subsequent procedure includes cutting the rear passenger side duct in half and removing the lower half to access the heater core connections, as well as removing the passenger kick panel. Notice the plastic on the side of the center console has been cut out to give access to the upper duct screw and the heater core connection screw (with a long screw driver or extension). The cutout was done with a dremel tool, and a small file was used to smooth it out.
Cutting and notching the Dash Support Bracket
One cut and a small notch needs to be made on a metal bracket under the dashboard so that the bottom of the dashboard can be bent out of the way slightly to slide the heater core out of its compartment.
Unbolting the Lower Dash Mounts and Extracting the Heater Core
Three bolts at the bottom of the dashboard mounts need to be removed in the passenger footwell. (see photo below).
The bottom of the dash can now be pulled out just enough to slide the heater core out of it's compartment after the pipes have been disconnected and the lower distribution servo has been removed (two small screws).
Once the new heater core has been installed, the bracket that was cut is now braced with some aluminum flat stock and self tapping screws.
The remainder of the dash and glovebox reassembly is straight forward, following the reverse order of disassembly. Chuck was very happy that this repair could be done in just a few hours time using these shortcuts.
Chuck is not sure if the above method would be of any help to RHD Range Rover owners.
Core Genuine Part Number STC3261.
Sources for new heater cores are detailed at http://rangerovers.net/rrparts4.html#climate
Dash Removal Method: Jos Geuze removed his dash (fascia), which is the O-ring access method recommended in the shop manual. He found this is not as difficult an operation as previously thought, and has provided a full illustrated description on the dash removal page.
Heater Core O-Ring Replacement Page: Details of diagnosis and procedures to be followed before resorting to heater core replacement.