Models: ALL, Years: ALL

Here, in Pennsylvania, it gets pretty cold and raw in the Winter. Not as bad as northern Minnesota (where I lived for a year), but cold enough that you want a good heating system in your truck. It didn't take but a few weeks into the colder part of the year before I realized that I was going to freeze my a$$ off in the Pinz. The exhaust heat exchange on the Pinzgauer actually generates quite a bit of heat. Unfortunately the design of the truck is such that most of the heat is dissipated before it has a chance to warm the passengers. The following is my analysis of the problem(s) and my suggestions.

These comments are specific to the 710K, but are also pertain to the 710M and 712 M. Please feel free to add to the knowledge base. ..

Problem: No insulation.
Discussion: The Pinzgauer has no thermal insulation and any heat that enters the cab is quickly dissipated. Air infiltration around the doors and windows allows cold outside air to enter the cab. The huge volume of air in the back of a 710K cannot be effectively heated by the engine heat alone.

Solution: Add thermal insulation to the walls, ceiling and floor. Insulation can take many forms: fiberglass, foam, or even foil faced bubble wrap. Even carpet adds some insulation. Replace worn or torn weatherstripping on the doors. If you don?t regularly carry passengers in the back, consider replacing the blackout curtain with clear vinyl to keep all the heat in the front (if you don't have an inside rear view mirror, or don't care about seeing out the back, then just use the blackout curtain).

Problem:Heating ducts not insulated.
Discussion: The ducts from the heat exchanger to the cab are not insulated and are under the truck in the cold air.

Solution: Insulate the ducts. I used 4 in. wide strips of Reflectix (foil-faced bubble wrap) spiral wound around the ducts and held in place with aluminum duct tape. This alone made a BIG difference in the temperature of the air entering the cab. Note: Don?t use the Reflectix too close to the heat exchanger ? it is only rated to 160 degrees F.

Problem: Leaking fresh air valve.
Discussion: The fresh air inlet valve can develop leaks if the seal deteriorates.

Solution: Replace the fresh air inlet valve or renew the seal.

Problem: Insufficient air volume.
Discussion: The heater blower only has two speeds (on and off). Also, heater blower inlet can get clogged with debris.

Solution: No specific solution known. A multi-speed blower or a continuously variable speed blower would be better. Also, an inline axial blower would help move the heated air. Remove heater blower and check inlet for debris.

Problem: No provision for recirculating air.
Discussion: All of the air entering the heating system enters from the outside (at the back of the engine compartment).

Solution: No specific solution known. Perhaps a tee at the back of the engine compartment with a short hose leading to the cab. You would also need a flapper valve and control cable to regulate recirculating air.

Problem: Heat exchanger and heater valve box leaks.
Discussion: The heat exchanger has some openings where it joins the exhaust pipe and the heater valve box has some small openings. All of these openings allow heater air to escape or cold air to enter.

Solution: Seal the openings in the heat exchanger with a high temperature putty such as POR Fire Seal 2000. Openings in the heater valve box can be sealed with silicone rubber.

Problem: Heat exchanger not insulated.
Discussion: The heat exchanger presents a large surface area to cold outside air and loses a lot of heat.

Solution: No specific solution known. Insulate the heat exchanger with some type of high temperature insulation. I have heard that a ceramic coating on the heat exchanger helps eliminate heat loss.

Further thoughts:
Wouldn't it be nice to have the Eberspächer heater discharge into the cab instead of the back? The previous owner of my truck cut a 3 in. dia hole into the discharge end of the Eberspächer so that the heat goes into the cab. You could get creative with this idea and maybe have the Eberspächer discharge into the heat exchanger inlet hose (seems easy to do).

Contributed by Jay Reich