3. Though the installation of the Mojave Heater is fairly simple, it is somewhat time-consuming. The heater hoses that go to the Mojave Heater must be connected to the feed and return connections on the water pump and engine. That means you'll have to go through your firewall, and this can be done drilling all new holes or by reusing part of your old heater core. We simply cut the end tubes off of our heater core (behind the dash), connected heater hoses from them to the Mojave Heater, and changed nothing inside the engine compartment.